BeanFactory实现的简单容器
BeanFactory实现Ioc
public class SimpleBeanFactory {
public static void main(String[] args) {
ClassPathResource resource = new ClassPathResource("applicationContext.xml");
XmlBeanFactory beanFactory = new XmlBeanFactory(resource);
Student student = beanFactory.getBean("student",Student.class);
student.setName("小明");
student.setAge(24);
student.printAge();
}
}
BeanFactory源码
package org.springframework.beans.factory;
import org.springframework.beans.BeansException;
import org.springframework.core.ResolvableType;
/**
* BeanFactory作为最原始同时也最重要的Ioc容器,它主要的功能是为依赖注入 （DI） 提供支持， BeanFactory 和相关的接口，比如，BeanFactoryAware、
* DisposableBean、InitializingBean，仍旧保留在 Spring 中，主要目的是向后兼容已经存在的和那些 Spring 整合在一起的第三方框架。在 Spring 中
* ，有大量对 BeanFactory 接口的实现。其中，最常被使用的是 XmlBeanFactory 类。这个容器从一个 XML 文件中读取配置元数据，由这些元数据来生成一
* 个被配置化的系统或者应用。在资源宝贵的移动设备或者基于applet的应用当中， BeanFactory 会被优先选择。否则，一般使用的是 ApplicationContext
*
* 这里定义的只是一系列的接口方法，通过这一系列的BeanFactory接口，可以使用不同的Bean的检索方法很方便地从Ioc容器中得到需要的Bean，从而忽略具体
* 的Ioc容器的实现，从这个角度上看，这些检索方法代表的是最为基本的容器入口。
*
* @author Rod Johnson
* @author Juergen Hoeller
* @author Chris Beams
* @since 13 April 2001
*/
public interface BeanFactory {
/**
* 转定义符"&" 用来引用实例，或把它和工厂产生的Bean区分开，就是说，如果一个FactoryBean的名字为a，那么，&a会得到那个Factory
*
* FactoryBean和BeanFactory 是在Spring中使用最为频繁的类，它们在拼写上很相似。一个是Factory，也就是Ioc容器或对象工厂；一个
* 是Bean。在Spring中，所有的Bean都是由BeanFactory（也就是Ioc容器）来进行管理的。但对FactoryBean而言，这个Bean不是简单的Be
* an，而是一个能产生或者修饰对象生成的工厂Bean，它的实现与设计模式中的工厂模式和修饰器模式类似。
*/
String FACTORY_BEAN_PREFIX = "&";
/**
* 五个不同形式的getBean方法，获取实例
* @param name 检索所用的Bean名
* @return Object（<T> T） 实例对象
* @throws BeansException 如果Bean不能取得
*/
Object getBean(String name) throws BeansException;
<T> T getBean(String name, Class<T> requiredType) throws BeansException;
<T> T getBean(Class<T> requiredType) throws BeansException;
Object getBean(String name, Object... args) throws BeansException;
<T> T getBean(Class<T> requiredType, Object... args) throws BeansException;
/**
* 让用户判断容器是否含有指定名字的Bean.
* @param name 搜索所用的Bean名
* @return boolean 是否包含其中
*/
boolean containsBean(String name);
/**
* 查询指定名字的Bean是否是Singleton类型的Bean.
* 对于Singleton属性，可以在BeanDefinition指定.
* @param name 搜索所用的Bean名
* @return boolean 是否包是Singleton
* @throws NoSuchBeanDefinitionException 没有找到Bean
*/
boolean isSingleton(String name) throws NoSuchBeanDefinitionException;
/**
* 查询指定名字的Bean是否是Prototype类型的。
* 与Singleton属性一样，可以在BeanDefinition指定.
* @param name 搜索所用的Bean名
* @return boolean 是否包是Prototype
* @throws NoSuchBeanDefinitionException 没有找到Bean
*/
boolean isPrototype(String name) throws NoSuchBeanDefinitionException;
/**
* 查询指定了名字的Bean的Class类型是否是特定的Class类型.
* @param name 搜索所用的Bean名
* @param typeToMatch 匹配类型
* @return boolean 是否是特定类型
* @throws NoSuchBeanDefinitionException 没有找到Bean
*/
boolean isTypeMatch(String name, ResolvableType typeToMatch) throws NoSuchBeanDefinitionException;
boolean isTypeMatch(String name, Class<?> typeToMatch) throws NoSuchBeanDefinitionException;
/**
* 查询指定名字的Bean的Class类型.
* @param name 搜索所用的Bean名
* @return 指定的Bean或者null(没有找到合适的Bean)
* @throws NoSuchBeanDefinitionException 没有找到Bean
*/
Class<?> getType(String name) throws NoSuchBeanDefinitionException;
/**
* 查询指定了名字的Bean的所有别名，这些都是在BeanDefinition中定义的
* @param name 搜索所用的Bean名
* @return 指定名字的Bean的所有别名 或者一个空的数组
*/
String[] getAliases(String name);
}
BeanFactory的实现类XmlBeanFactory
package org.springframework.beans.factory.xml;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.core.io.Resource;
/**
* XmlBeanFactory是BeanFactory的最简单实现类
*
* XmlBeanFactory的功能是建立在DefaultListableBeanFactory这个基本容器的基础上的，并在这个基本容器的基础上实行了其他诸如
* XML读取的附加功能。XmlBeanFactory使用了DefaultListableBeanFactory作为基础类，DefaultListableBeanFactory是一个很重
* 要的Ioc实现，会在下一章进行重点论述。
*
* @author Rod Johnson
* @author Juergen Hoeller
* @author Chris Beams
* @since 15 April 2001
*/
public class XmlBeanFactory extends DefaultListableBeanFactory {
private final XmlBeanDefinitionReader reader = new XmlBeanDefinitionReader(this);
/**
* 根据给定来源，创建一个XmlBeanFactory
* @param resource Spring中对与外部资源的抽象，最常见的是对文件的抽象，特别是XML文件。而且Resource里面通常
* 是保存了Spring使用者的Bean定义，比如applicationContext.xml在被加载时，就会被抽象为Resource来处理。
* @throws BeansException 载入或者解析中发生错误
*/
public XmlBeanFactory(Resource resource) throws BeansException {
this(resource, null);
}
/**
* 根据给定来源和BeanFactory，创建一个XmlBeanFactory
* @param resource Spring中对与外部资源的抽象，最常见的是对文件的抽象，特别是XML文件。而且Resource里面通常
* 是保存了Spring使用者的Bean定义，比如applicationContext.xml在被加载时，就会被抽象为Resource来处理。
* @param parentBeanFactory 父类的BeanFactory
* @throws BeansException 载入或者解析中发生错误
*/
public XmlBeanFactory(Resource resource, BeanFactory parentBeanFactory) throws BeansException {
super(parentBeanFactory);
this.reader.loadBeanDefinitions(resource);
}
}
DefaultListableBeanFactory的源码
/*
* Copyright 2002-2018 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.beans.factory.support;
import java.io.IOException;
import java.io.NotSerializableException;
import java.io.ObjectInputStream;
import java.io.ObjectStreamException;
import java.io.Serializable;
import java.lang.annotation.Annotation;
import java.lang.ref.Reference;
import java.lang.ref.WeakReference;
import java.lang.reflect.Method;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Comparator;
import java.util.IdentityHashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import javax.inject.Provider;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.BeansException;
import org.springframework.beans.TypeConverter;
import org.springframework.beans.factory.BeanCreationException;
import org.springframework.beans.factory.BeanCurrentlyInCreationException;
import org.springframework.beans.factory.BeanDefinitionStoreException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.BeanFactoryUtils;
import org.springframework.beans.factory.BeanNotOfRequiredTypeException;
import org.springframework.beans.factory.CannotLoadBeanClassException;
import org.springframework.beans.factory.FactoryBean;
import org.springframework.beans.factory.InjectionPoint;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.beans.factory.NoUniqueBeanDefinitionException;
import org.springframework.beans.factory.ObjectFactory;
import org.springframework.beans.factory.ObjectProvider;
import org.springframework.beans.factory.SmartFactoryBean;
import org.springframework.beans.factory.SmartInitializingSingleton;
import org.springframework.beans.factory.config.AutowireCapableBeanFactory;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.BeanDefinitionHolder;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.config.DependencyDescriptor;
import org.springframework.beans.factory.config.NamedBeanHolder;
import org.springframework.core.OrderComparator;
import org.springframework.core.ResolvableType;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.CompositeIterator;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;
/**
* ListableBeanFactory接口和BeanDefinitionRegistry接口的默认实现类，一个基于
* BeanDefinition对象的成熟的BeanFactory
*
* <p>Typical usage is registering all bean definitions first (possibly read
* from a bean definition file), before accessing beans. Bean definition lookup
* is therefore an inexpensive operation in a local bean definition table,
* operating on pre-built bean definition metadata objects.
*
* <p>Can be used as a standalone bean factory, or as a superclass for custom
* bean factories. Note that readers for specific bean definition formats are
* typically implemented separately rather than as bean factory subclasses:
* see for example {@link PropertiesBeanDefinitionReader} and
* {@link org.springframework.beans.factory.xml.XmlBeanDefinitionReader}.
*
* <p>For an alternative implementation of the
* {@link org.springframework.beans.factory.ListableBeanFactory} interface,
* have a look at {@link StaticListableBeanFactory}, which manages existing
* bean instances rather than creating new ones based on bean definitions.
*
* @author Rod Johnson
* @author Juergen Hoeller
* @author Sam Brannen
* @author Costin Leau
* @author Chris Beams
* @author Phillip Webb
* @author Stephane Nicoll
* @since 16 April 2001
* @see StaticListableBeanFactory
* @see PropertiesBeanDefinitionReader
* @see org.springframework.beans.factory.xml.XmlBeanDefinitionReader
*/
@SuppressWarnings("serial")
public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFactory
implements ConfigurableListableBeanFactory, BeanDefinitionRegistry, Serializable {
@Nullable
private static Class<?> javaxInjectProviderClass;
static {
try {
javaxInjectProviderClass =
ClassUtils.forName("javax.inject.Provider", DefaultListableBeanFactory.class.getClassLoader());
}
catch (ClassNotFoundException ex) {
// JSR-330 API not available - Provider interface simply not supported then.
javaxInjectProviderClass = null;
}
}
/** Map from serialized id to factory instance */
private static final Map<String, Reference<DefaultListableBeanFactory>> serializableFactories =
new ConcurrentHashMap<>(8);
/** Optional id for this factory, for serialization purposes */
@Nullable
private String serializationId;
/** Whether to allow re-registration of a different definition with the same name */
private boolean allowBeanDefinitionOverriding = true;
/** Whether to allow eager class loading even for lazy-init beans */
private boolean allowEagerClassLoading = true;
/** Optional OrderComparator for dependency Lists and arrays */
@Nullable
private Comparator<Object> dependencyComparator;
/** Resolver to use for checking if a bean definition is an autowire candidate */
private AutowireCandidateResolver autowireCandidateResolver = new SimpleAutowireCandidateResolver();
/** Map from dependency type to corresponding autowired value */
private final Map<Class<?>, Object> resolvableDependencies = new ConcurrentHashMap<>(16);
/** Map of bean definition objects, keyed by bean name */
private final Map<String, BeanDefinition> beanDefinitionMap = new ConcurrentHashMap<>(256);
/** Map of singleton and non-singleton bean names, keyed by dependency type */
private final Map<Class<?>, String[]> allBeanNamesByType = new ConcurrentHashMap<>(64);
/** Map of singleton-only bean names, keyed by dependency type */
private final Map<Class<?>, String[]> singletonBeanNamesByType = new ConcurrentHashMap<>(64);
/** List of bean definition names, in registration order */
private volatile List<String> beanDefinitionNames = new ArrayList<>(256);
/** List of names of manually registered singletons, in registration order */
private volatile Set<String> manualSingletonNames = new LinkedHashSet<>(16);
/** Cached array of bean definition names in case of frozen configuration */
@Nullable
private volatile String[] frozenBeanDefinitionNames;
/** Whether bean definition metadata may be cached for all beans */
private volatile boolean configurationFrozen = false;
/**
* Create a new DefaultListableBeanFactory.
*/
public DefaultListableBeanFactory() {
super();
}
/**
* Create a new DefaultListableBeanFactory with the given parent.
* @param parentBeanFactory the parent BeanFactory
*/
public DefaultListableBeanFactory(@Nullable BeanFactory parentBeanFactory) {
super(parentBeanFactory);
}
/**
* Specify an id for serialization purposes, allowing this BeanFactory to be
* deserialized from this id back into the BeanFactory object, if needed.
*/
public void setSerializationId(@Nullable String serializationId) {
if (serializationId != null) {
serializableFactories.put(serializationId, new WeakReference<>(this));
}
else if (this.serializationId != null) {
serializableFactories.remove(this.serializationId);
}
this.serializationId = serializationId;
}
/**
* Return an id for serialization purposes, if specified, allowing this BeanFactory
* to be deserialized from this id back into the BeanFactory object, if needed.
* @since 4.1.2
*/
@Nullable
public String getSerializationId() {
return this.serializationId;
}
/**
* Set whether it should be allowed to override bean definitions by registering
* a different definition with the same name, automatically replacing the former.
* If not, an exception will be thrown. This also applies to overriding aliases.
* <p>Default is "true".
* @see #registerBeanDefinition
*/
public void setAllowBeanDefinitionOverriding(boolean allowBeanDefinitionOverriding) {
this.allowBeanDefinitionOverriding = allowBeanDefinitionOverriding;
}
/**
* Return whether it should be allowed to override bean definitions by registering
* a different definition with the same name, automatically replacing the former.
* @since 4.1.2
*/
public boolean isAllowBeanDefinitionOverriding() {
return this.allowBeanDefinitionOverriding;
}
/**
* Set whether the factory is allowed to eagerly load bean classes
* even for bean definitions that are marked as "lazy-init".
* <p>Default is "true". Turn this flag off to suppress class loading
* for lazy-init beans unless such a bean is explicitly requested.
* In particular, by-type lookups will then simply ignore bean definitions
* without resolved class name, instead of loading the bean classes on
* demand just to perform a type check.
* @see AbstractBeanDefinition#setLazyInit
*/
public void setAllowEagerClassLoading(boolean allowEagerClassLoading) {
this.allowEagerClassLoading = allowEagerClassLoading;
}
/**
* Return whether the factory is allowed to eagerly load bean classes
* even for bean definitions that are marked as "lazy-init".
* @since 4.1.2
*/
public boolean isAllowEagerClassLoading() {
return this.allowEagerClassLoading;
}
/**
* Set a {@link java.util.Comparator} for dependency Lists and arrays.
* @since 4.0
* @see org.springframework.core.OrderComparator
* @see org.springframework.core.annotation.AnnotationAwareOrderComparator
*/
public void setDependencyComparator(@Nullable Comparator<Object> dependencyComparator) {
this.dependencyComparator = dependencyComparator;
}
/**
* Return the dependency comparator for this BeanFactory (may be {@code null}.
* @since 4.0
*/
@Nullable
public Comparator<Object> getDependencyComparator() {
return this.dependencyComparator;
}
/**
* Set a custom autowire candidate resolver for this BeanFactory to use
* when deciding whether a bean definition should be considered as a
* candidate for autowiring.
*/
public void setAutowireCandidateResolver(final AutowireCandidateResolver autowireCandidateResolver) {
Assert.notNull(autowireCandidateResolver, "AutowireCandidateResolver must not be null");
if (autowireCandidateResolver instanceof BeanFactoryAware) {
if (System.getSecurityManager() != null) {
AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
((BeanFactoryAware) autowireCandidateResolver).setBeanFactory(DefaultListableBeanFactory.this);
return null;
}, getAccessControlContext());
}
else {
((BeanFactoryAware) autowireCandidateResolver).setBeanFactory(this);
}
}
this.autowireCandidateResolver = autowireCandidateResolver;
}
/**
* Return the autowire candidate resolver for this BeanFactory (never {@code null}).
*/
public AutowireCandidateResolver getAutowireCandidateResolver() {
return this.autowireCandidateResolver;
}
@Override
public void copyConfigurationFrom(ConfigurableBeanFactory otherFactory) {
super.copyConfigurationFrom(otherFactory);
if (otherFactory instanceof DefaultListableBeanFactory) {
DefaultListableBeanFactory otherListableFactory = (DefaultListableBeanFactory) otherFactory;
this.allowBeanDefinitionOverriding = otherListableFactory.allowBeanDefinitionOverriding;
this.allowEagerClassLoading = otherListableFactory.allowEagerClassLoading;
this.dependencyComparator = otherListableFactory.dependencyComparator;
// A clone of the AutowireCandidateResolver since it is potentially BeanFactoryAware...
setAutowireCandidateResolver(BeanUtils.instantiateClass(getAutowireCandidateResolver().getClass()));
// Make resolvable dependencies (e.g. ResourceLoader) available here as well...
this.resolvableDependencies.putAll(otherListableFactory.resolvableDependencies);
}
}
//---------------------------------------------------------------------
// Implementation of remaining BeanFactory methods
//---------------------------------------------------------------------
@Override
public <T> T getBean(Class<T> requiredType) throws BeansException {
return getBean(requiredType, (Object[]) null);
}
@Override
public <T> T getBean(Class<T> requiredType, @Nullable Object... args) throws BeansException {
NamedBeanHolder<T> namedBean = resolveNamedBean(requiredType, args);
if (namedBean != null) {
return namedBean.getBeanInstance();
}
BeanFactory parent = getParentBeanFactory();
if (parent != null) {
return (args != null ? parent.getBean(requiredType, args) : parent.getBean(requiredType));
}
throw new NoSuchBeanDefinitionException(requiredType);
}
//---------------------------------------------------------------------
// Implementation of ListableBeanFactory interface
//---------------------------------------------------------------------
@Override
public boolean containsBeanDefinition(String beanName) {
Assert.notNull(beanName, "Bean name must not be null");
return this.beanDefinitionMap.containsKey(beanName);
}
@Override
public int getBeanDefinitionCount() {
return this.beanDefinitionMap.size();
}
@Override
public String[] getBeanDefinitionNames() {
String[] frozenNames = this.frozenBeanDefinitionNames;
if (frozenNames != null) {
return frozenNames.clone();
}
else {
return StringUtils.toStringArray(this.beanDefinitionNames);
}
}
@Override
public String[] getBeanNamesForType(ResolvableType type) {
return doGetBeanNamesForType(type, true, true);
}
@Override
public String[] getBeanNamesForType(@Nullable Class<?> type) {
return getBeanNamesForType(type, true, true);
}
@Override
public String[] getBeanNamesForType(@Nullable Class<?> type, boolean includeNonSingletons, boolean allowEagerInit) {
if (!isConfigurationFrozen() || type == null || !allowEagerInit) {
return doGetBeanNamesForType(ResolvableType.forRawClass(type), includeNonSingletons, allowEagerInit);
}
Map<Class<?>, String[]> cache =
(includeNonSingletons ? this.allBeanNamesByType : this.singletonBeanNamesByType);
String[] resolvedBeanNames = cache.get(type);
if (resolvedBeanNames != null) {
return resolvedBeanNames;
}
resolvedBeanNames = doGetBeanNamesForType(ResolvableType.forRawClass(type), includeNonSingletons, true);
if (ClassUtils.isCacheSafe(type, getBeanClassLoader())) {
cache.put(type, resolvedBeanNames);
}
return resolvedBeanNames;
}
private String[] doGetBeanNamesForType(ResolvableType type, boolean includeNonSingletons, boolean allowEagerInit) {
List<String> result = new ArrayList<>();
// Check all bean definitions.
for (String beanName : this.beanDefinitionNames) {
// Only consider bean as eligible if the bean name
// is not defined as alias for some other bean.
if (!isAlias(beanName)) {
try {
RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
// Only check bean definition if it is complete.
if (!mbd.isAbstract() && (allowEagerInit ||
(mbd.hasBeanClass() || !mbd.isLazyInit() || isAllowEagerClassLoading()) &&
!requiresEagerInitForType(mbd.getFactoryBeanName()))) {
// In case of FactoryBean, match object created by FactoryBean.
boolean isFactoryBean = isFactoryBean(beanName, mbd);
BeanDefinitionHolder dbd = mbd.getDecoratedDefinition();
boolean matchFound =
(allowEagerInit || !isFactoryBean ||
(dbd != null && !mbd.isLazyInit()) || containsSingleton(beanName)) &&
(includeNonSingletons ||
(dbd != null ? mbd.isSingleton() : isSingleton(beanName))) &&
isTypeMatch(beanName, type);
if (!matchFound && isFactoryBean) {
// In case of FactoryBean, try to match FactoryBean instance itself next.
beanName = FACTORY_BEAN_PREFIX + beanName;
matchFound = (includeNonSingletons || mbd.isSingleton()) && isTypeMatch(beanName, type);
}
if (matchFound) {
result.add(beanName);
}
}
}
catch (CannotLoadBeanClassException ex) {
if (allowEagerInit) {
throw ex;
}
// Probably contains a placeholder: let's ignore it for type matching purposes.
if (this.logger.isDebugEnabled()) {
this.logger.debug("Ignoring bean class loading failure for bean '" + beanName + "'", ex);
}
onSuppressedException(ex);
}
catch (BeanDefinitionStoreException ex) {
if (allowEagerInit) {
throw ex;
}
// Probably contains a placeholder: let's ignore it for type matching purposes.
if (this.logger.isDebugEnabled()) {
this.logger.debug("Ignoring unresolvable metadata in bean definition '" + beanName + "'", ex);
}
onSuppressedException(ex);
}
}
}
// Check manually registered singletons too.
for (String beanName : this.manualSingletonNames) {
try {
// In case of FactoryBean, match object created by FactoryBean.
if (isFactoryBean(beanName)) {
if ((includeNonSingletons || isSingleton(beanName)) && isTypeMatch(beanName, type)) {
result.add(beanName);
// Match found for this bean: do not match FactoryBean itself anymore.
continue;
}
// In case of FactoryBean, try to match FactoryBean itself next.
beanName = FACTORY_BEAN_PREFIX + beanName;
}
// Match raw bean instance (might be raw FactoryBean).
if (isTypeMatch(beanName, type)) {
result.add(beanName);
}
}
catch (NoSuchBeanDefinitionException ex) {
// Shouldn't happen - probably a result of circular reference resolution...
if (logger.isDebugEnabled()) {
logger.debug("Failed to check manually registered singleton with name '" + beanName + "'", ex);
}
}
}
return StringUtils.toStringArray(result);
}
/**
* Check whether the specified bean would need to be eagerly initialized
* in order to determine its type.
* @param factoryBeanName a factory-bean reference that the bean definition
* defines a factory method for
* @return whether eager initialization is necessary
*/
private boolean requiresEagerInitForType(@Nullable String factoryBeanName) {
return (factoryBeanName != null && isFactoryBean(factoryBeanName) && !containsSingleton(factoryBeanName));
}
@Override
public <T> Map<String, T> getBeansOfType(@Nullable Class<T> type) throws BeansException {
return getBeansOfType(type, true, true);
}
@Override
@SuppressWarnings("unchecked")
public <T> Map<String, T> getBeansOfType(@Nullable Class<T> type, boolean includeNonSingletons, boolean allowEagerInit)
throws BeansException {
String[] beanNames = getBeanNamesForType(type, includeNonSingletons, allowEagerInit);
Map<String, T> result = new LinkedHashMap<>(beanNames.length);
for (String beanName : beanNames) {
try {
Object beanInstance = getBean(beanName);
result.put(beanName, (beanInstance instanceof NullBean ? null : (T) beanInstance));
}
catch (BeanCreationException ex) {
Throwable rootCause = ex.getMostSpecificCause();
if (rootCause instanceof BeanCurrentlyInCreationException) {
BeanCreationException bce = (BeanCreationException) rootCause;
String exBeanName = bce.getBeanName();
if (exBeanName != null && isCurrentlyInCreation(exBeanName)) {
if (this.logger.isDebugEnabled()) {
this.logger.debug("Ignoring match to currently created bean '" + exBeanName + "': " +
ex.getMessage());
}
onSuppressedException(ex);
// Ignore: indicates a circular reference when autowiring constructors.
// We want to find matches other than the currently created bean itself.
continue;
}
}
throw ex;
}
}
return result;
}
@Override
public String[] getBeanNamesForAnnotation(Class<? extends Annotation> annotationType) {
List<String> results = new ArrayList<>();
for (String beanName : this.beanDefinitionNames) {
BeanDefinition beanDefinition = getBeanDefinition(beanName);
if (!beanDefinition.isAbstract() && findAnnotationOnBean(beanName, annotationType) != null) {
results.add(beanName);
}
}
for (String beanName : this.manualSingletonNames) {
if (!results.contains(beanName) && findAnnotationOnBean(beanName, annotationType) != null) {
results.add(beanName);
}
}
return StringUtils.toStringArray(results);
}
@Override
public Map<String, Object> getBeansWithAnnotation(Class<? extends Annotation> annotationType) {
String[] beanNames = getBeanNamesForAnnotation(annotationType);
Map<String, Object> results = new LinkedHashMap<>(beanNames.length);
for (String beanName : beanNames) {
results.put(beanName, getBean(beanName));
}
return results;
}
/**
* Find a {@link Annotation} of {@code annotationType} on the specified
* bean, traversing its interfaces and super classes if no annotation can be
* found on the given class itself, as well as checking its raw bean class
* if not found on the exposed bean reference (e.g. in case of a proxy).
*/
@Override
@Nullable
public <A extends Annotation> A findAnnotationOnBean(String beanName, Class<A> annotationType)
throws NoSuchBeanDefinitionException{
A ann = null;
Class<?> beanType = getType(beanName);
if (beanType != null) {
ann = AnnotationUtils.findAnnotation(beanType, annotationType);
}
if (ann == null && containsBeanDefinition(beanName)) {
BeanDefinition bd = getMergedBeanDefinition(beanName);
if (bd instanceof AbstractBeanDefinition) {
AbstractBeanDefinition abd = (AbstractBeanDefinition) bd;
if (abd.hasBeanClass()) {
ann = AnnotationUtils.findAnnotation(abd.getBeanClass(), annotationType);
}
}
}
return ann;
}
//---------------------------------------------------------------------
// Implementation of ConfigurableListableBeanFactory interface
//---------------------------------------------------------------------
@Override
public void registerResolvableDependency(Class<?> dependencyType, @Nullable Object autowiredValue) {
Assert.notNull(dependencyType, "Dependency type must not be null");
if (autowiredValue != null) {
if (!(autowiredValue instanceof ObjectFactory || dependencyType.isInstance(autowiredValue))) {
throw new IllegalArgumentException("Value [" + autowiredValue +
"] does not implement specified dependency type [" + dependencyType.getName() + "]");
}
this.resolvableDependencies.put(dependencyType, autowiredValue);
}
}
@Override
public boolean isAutowireCandidate(String beanName, DependencyDescriptor descriptor)
throws NoSuchBeanDefinitionException {
return isAutowireCandidate(beanName, descriptor, getAutowireCandidateResolver());
}
/**
* Determine whether the specified bean definition qualifies as an autowire candidate,
* to be injected into other beans which declare a dependency of matching type.
* @param beanName the name of the bean definition to check
* @param descriptor the descriptor of the dependency to resolve
* @param resolver the AutowireCandidateResolver to use for the actual resolution algorithm
* @return whether the bean should be considered as autowire candidate
*/
protected boolean isAutowireCandidate(String beanName, DependencyDescriptor descriptor, AutowireCandidateResolver resolver)
throws NoSuchBeanDefinitionException {
String beanDefinitionName = BeanFactoryUtils.transformedBeanName(beanName);
if (containsBeanDefinition(beanDefinitionName)) {
return isAutowireCandidate(beanName, getMergedLocalBeanDefinition(beanDefinitionName), descriptor, resolver);
}
else if (containsSingleton(beanName)) {
return isAutowireCandidate(beanName, new RootBeanDefinition(getType(beanName)), descriptor, resolver);
}
BeanFactory parent = getParentBeanFactory();
if (parent instanceof DefaultListableBeanFactory) {
// No bean definition found in this factory -> delegate to parent.
return ((DefaultListableBeanFactory) parent).isAutowireCandidate(beanName, descriptor, resolver);
}
else if (parent instanceof ConfigurableListableBeanFactory) {
// If no DefaultListableBeanFactory, can't pass the resolver along.
return ((ConfigurableListableBeanFactory) parent).isAutowireCandidate(beanName, descriptor);
}
else {
return true;
}
}
/**
* Determine whether the specified bean definition qualifies as an autowire candidate,
* to be injected into other beans which declare a dependency of matching type.
* @param beanName the name of the bean definition to check
* @param mbd the merged bean definition to check
* @param descriptor the descriptor of the dependency to resolve
* @param resolver the AutowireCandidateResolver to use for the actual resolution algorithm
* @return whether the bean should be considered as autowire candidate
*/
protected boolean isAutowireCandidate(String beanName, RootBeanDefinition mbd,
DependencyDescriptor descriptor, AutowireCandidateResolver resolver) {
String beanDefinitionName = BeanFactoryUtils.transformedBeanName(beanName);
resolveBeanClass(mbd, beanDefinitionName);
if (mbd.isFactoryMethodUnique) {
boolean resolve;
synchronized (mbd.constructorArgumentLock) {
resolve = (mbd.resolvedConstructorOrFactoryMethod == null);
}
if (resolve) {
new ConstructorResolver(this).resolveFactoryMethodIfPossible(mbd);
}
}
return resolver.isAutowireCandidate(
new BeanDefinitionHolder(mbd, beanName, getAliases(beanDefinitionName)), descriptor);
}
@Override
public BeanDefinition getBeanDefinition(String beanName) throws NoSuchBeanDefinitionException {
BeanDefinition bd = this.beanDefinitionMap.get(beanName);
if (bd == null) {
if (this.logger.isTraceEnabled()) {
this.logger.trace("No bean named '" + beanName + "' found in " + this);
}
throw new NoSuchBeanDefinitionException(beanName);
}
return bd;
}
@Override
public Iterator<String> getBeanNamesIterator() {
CompositeIterator<String> iterator = new CompositeIterator<>();
iterator.add(this.beanDefinitionNames.iterator());
iterator.add(this.manualSingletonNames.iterator());
return iterator;
}
@Override
public void clearMetadataCache() {
super.clearMetadataCache();
clearByTypeCache();
}
@Override
public void freezeConfiguration() {
this.configurationFrozen = true;
this.frozenBeanDefinitionNames = StringUtils.toStringArray(this.beanDefinitionNames);
}
@Override
public boolean isConfigurationFrozen() {
return this.configurationFrozen;
}
/**
* Considers all beans as eligible for metadata caching
* if the factory's configuration has been marked as frozen.
* @see #freezeConfiguration()
*/
@Override
protected boolean isBeanEligibleForMetadataCaching(String beanName) {
return (this.configurationFrozen || super.isBeanEligibleForMetadataCaching(beanName));
}
@Override
public void preInstantiateSingletons() throws BeansException {
if (this.logger.isDebugEnabled()) {
this.logger.debug("Pre-instantiating singletons in " + this);
}
// Iterate over a copy to allow for init methods which in turn register new bean definitions.
// While this may not be part of the regular factory bootstrap, it does otherwise work fine.
List<String> beanNames = new ArrayList<>(this.beanDefinitionNames);
// Trigger initialization of all non-lazy singleton beans...
for (String beanName : beanNames) {
RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName);
if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
if (isFactoryBean(beanName)) {
Object bean = getBean(FACTORY_BEAN_PREFIX + beanName);
if (bean instanceof FactoryBean) {
final FactoryBean<?> factory = (FactoryBean<?>) bean;
boolean isEagerInit;
if (System.getSecurityManager() != null && factory instanceof SmartFactoryBean) {
isEagerInit = AccessController.doPrivileged((PrivilegedAction<Boolean>)
((SmartFactoryBean<?>) factory)::isEagerInit,
getAccessControlContext());
}
else {
isEagerInit = (factory instanceof SmartFactoryBean &&
((SmartFactoryBean<?>) factory).isEagerInit());
}
if (isEagerInit) {
getBean(beanName);
}
}
}
else {
getBean(beanName);
}
}
}
// Trigger post-initialization callback for all applicable beans...
for (String beanName : beanNames) {
Object singletonInstance = getSingleton(beanName);
if (singletonInstance instanceof SmartInitializingSingleton) {
final SmartInitializingSingleton smartSingleton = (SmartInitializingSingleton) singletonInstance;
if (System.getSecurityManager() != null) {
AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
smartSingleton.afterSingletonsInstantiated();
return null;
}, getAccessControlContext());
}
else {
smartSingleton.afterSingletonsInstantiated();
}
}
}
}
//---------------------------------------------------------------------
// Implementation of BeanDefinitionRegistry interface
//---------------------------------------------------------------------
@Override
public void registerBeanDefinition(String beanName, BeanDefinition beanDefinition)
throws BeanDefinitionStoreException {
Assert.hasText(beanName, "Bean name must not be empty");
Assert.notNull(beanDefinition, "BeanDefinition must not be null");
if (beanDefinition instanceof AbstractBeanDefinition) {
try {
((AbstractBeanDefinition) beanDefinition).validate();
}
catch (BeanDefinitionValidationException ex) {
throw new BeanDefinitionStoreException(beanDefinition.getResourceDescription(), beanName,
"Validation of bean definition failed", ex);
}
}
BeanDefinition oldBeanDefinition;
oldBeanDefinition = this.beanDefinitionMap.get(beanName);
if (oldBeanDefinition != null) {
if (!isAllowBeanDefinitionOverriding()) {
throw new BeanDefinitionStoreException(beanDefinition.getResourceDescription(), beanName,
"Cannot register bean definition [" + beanDefinition + "] for bean '" + beanName +
"': There is already [" + oldBeanDefinition + "] bound.");
}
else if (oldBeanDefinition.getRole() < beanDefinition.getRole()) {
// e.g. was ROLE_APPLICATION, now overriding with ROLE_SUPPORT or ROLE_INFRASTRUCTURE
if (this.logger.isWarnEnabled()) {
this.logger.warn("Overriding user-defined bean definition for bean '" + beanName +
"' with a framework-generated bean definition: replacing [" +
oldBeanDefinition + "] with [" + beanDefinition + "]");
}
}
else if (!beanDefinition.equals(oldBeanDefinition)) {
if (this.logger.isInfoEnabled()) {
this.logger.info("Overriding bean definition for bean '" + beanName +
"' with a different definition: replacing [" + oldBeanDefinition +
"] with [" + beanDefinition + "]");
}
}
else {
if (this.logger.isDebugEnabled()) {
this.logger.debug("Overriding bean definition for bean '" + beanName +
"' with an equivalent definition: replacing [" + oldBeanDefinition +
"] with [" + beanDefinition + "]");
}
}
this.beanDefinitionMap.put(beanName, beanDefinition);
}
else {
if (hasBeanCreationStarted()) {
// Cannot modify startup-time collection elements anymore (for stable iteration)
synchronized (this.beanDefinitionMap) {
this.beanDefinitionMap.put(beanName, beanDefinition);
List<String> updatedDefinitions = new ArrayList<>(this.beanDefinitionNames.size() + 1);
updatedDefinitions.addAll(this.beanDefinitionNames);
updatedDefinitions.add(beanName);
this.beanDefinitionNames = updatedDefinitions;
if (this.manualSingletonNames.contains(beanName)) {
Set<String> updatedSingletons = new LinkedHashSet<>(this.manualSingletonNames);
updatedSingletons.remove(beanName);
this.manualSingletonNames = updatedSingletons;
}
}
}
else {
// Still in startup registration phase
this.beanDefinitionMap.put(beanName, beanDefinition);
this.beanDefinitionNames.add(beanName);
this.manualSingletonNames.remove(beanName);
}
this.frozenBeanDefinitionNames = null;
}
if (oldBeanDefinition != null || containsSingleton(beanName)) {
resetBeanDefinition(beanName);
}
}
@Override
public void removeBeanDefinition(String beanName) throws NoSuchBeanDefinitionException {
Assert.hasText(beanName, "'beanName' must not be empty");
BeanDefinition bd = this.beanDefinitionMap.remove(beanName);
if (bd == null) {
if (this.logger.isTraceEnabled()) {
this.logger.trace("No bean named '" + beanName + "' found in " + this);
}
throw new NoSuchBeanDefinitionException(beanName);
}
if (hasBeanCreationStarted()) {
// Cannot modify startup-time collection elements anymore (for stable iteration)
synchronized (this.beanDefinitionMap) {
List<String> updatedDefinitions = new ArrayList<>(this.beanDefinitionNames);
updatedDefinitions.remove(beanName);
this.beanDefinitionNames = updatedDefinitions;
}
}
else {
// Still in startup registration phase
this.beanDefinitionNames.remove(beanName);
}
this.frozenBeanDefinitionNames = null;
resetBeanDefinition(beanName);
}
/**
* Reset all bean definition caches for the given bean,
* including the caches of beans that are derived from it.
* @param beanName the name of the bean to reset
*/
protected void resetBeanDefinition(String beanName) {
// Remove the merged bean definition for the given bean, if already created.
clearMergedBeanDefinition(beanName);
// Remove corresponding bean from singleton cache, if any. Shouldn't usually
// be necessary, rather just meant for overriding a context's default beans
// (e.g. the default StaticMessageSource in a StaticApplicationContext).
destroySingleton(beanName);
// Reset all bean definitions that have the given bean as parent (recursively).
for (String bdName : this.beanDefinitionNames) {
if (!beanName.equals(bdName)) {
BeanDefinition bd = this.beanDefinitionMap.get(bdName);
if (beanName.equals(bd.getParentName())) {
resetBeanDefinition(bdName);
}
}
}
}
/**
* Only allows alias overriding if bean definition overriding is allowed.
*/
@Override
protected boolean allowAliasOverriding() {
return isAllowBeanDefinitionOverriding();
}
@Override
public void registerSingleton(String beanName, Object singletonObject) throws IllegalStateException {
super.registerSingleton(beanName, singletonObject);
if (hasBeanCreationStarted()) {
// Cannot modify startup-time collection elements anymore (for stable iteration)
synchronized (this.beanDefinitionMap) {
if (!this.beanDefinitionMap.containsKey(beanName)) {
Set<String> updatedSingletons = new LinkedHashSet<>(this.manualSingletonNames.size() + 1);
updatedSingletons.addAll(this.manualSingletonNames);
updatedSingletons.add(beanName);
this.manualSingletonNames = updatedSingletons;
}
}
}
else {
// Still in startup registration phase
if (!this.beanDefinitionMap.containsKey(beanName)) {
this.manualSingletonNames.add(beanName);
}
}
clearByTypeCache();
}
@Override
public void destroySingleton(String beanName) {
super.destroySingleton(beanName);
this.manualSingletonNames.remove(beanName);
clearByTypeCache();
}
@Override
public void destroySingletons() {
super.destroySingletons();
this.manualSingletonNames.clear();
clearByTypeCache();
}
/**
* Remove any assumptions about by-type mappings.
*/
private void clearByTypeCache() {
this.allBeanNamesByType.clear();
this.singletonBeanNamesByType.clear();
}
//---------------------------------------------------------------------
// Dependency resolution functionality
//---------------------------------------------------------------------
@Override
public <T> NamedBeanHolder<T> resolveNamedBean(Class<T> requiredType) throws BeansException {
NamedBeanHolder<T> namedBean = resolveNamedBean(requiredType, (Object[]) null);
if (namedBean != null) {
return namedBean;
}
BeanFactory parent = getParentBeanFactory();
if (parent instanceof AutowireCapableBeanFactory) {
return ((AutowireCapableBeanFactory) parent).resolveNamedBean(requiredType);
}
throw new NoSuchBeanDefinitionException(requiredType);
}
@SuppressWarnings("unchecked")
@Nullable
private <T> NamedBeanHolder<T> resolveNamedBean(Class<T> requiredType, @Nullable Object... args) throws BeansException {
Assert.notNull(requiredType, "Required type must not be null");
String[] candidateNames = getBeanNamesForType(requiredType);
if (candidateNames.length > 1) {
List<String> autowireCandidates = new ArrayList<>(candidateNames.length);
for (String beanName : candidateNames) {
if (!containsBeanDefinition(beanName) || getBeanDefinition(beanName).isAutowireCandidate()) {
autowireCandidates.add(beanName);
}
}
if (!autowireCandidates.isEmpty()) {
candidateNames = StringUtils.toStringArray(autowireCandidates);
}
}
if (candidateNames.length == 1) {
String beanName = candidateNames[0];
return new NamedBeanHolder<>(beanName, getBean(beanName, requiredType, args));
}
else if (candidateNames.length > 1) {
Map<String, Object> candidates = new LinkedHashMap<>(candidateNames.length);
for (String beanName : candidateNames) {
if (containsSingleton(beanName) && args == null) {
Object beanInstance = getBean(beanName);
candidates.put(beanName, (beanInstance instanceof NullBean ? null : beanInstance));
}
else {
candidates.put(beanName, getType(beanName));
}
}
String candidateName = determinePrimaryCandidate(candidates, requiredType);
if (candidateName == null) {
candidateName = determineHighestPriorityCandidate(candidates, requiredType);
}
if (candidateName != null) {
Object beanInstance = candidates.get(candidateName);
if (beanInstance == null || beanInstance instanceof Class) {
beanInstance = getBean(candidateName, requiredType, args);
}
return new NamedBeanHolder<>(candidateName, (T) beanInstance);
}
throw new NoUniqueBeanDefinitionException(requiredType, candidates.keySet());
}
return null;
}
@Override
@Nullable
public Object resolveDependency(DependencyDescriptor descriptor, @Nullable String requestingBeanName,
@Nullable Set<String> autowiredBeanNames, @Nullable TypeConverter typeConverter) throws BeansException {
descriptor.initParameterNameDiscovery(getParameterNameDiscoverer());
if (Optional.class == descriptor.getDependencyType()) {
return createOptionalDependency(descriptor, requestingBeanName);
}
else if (ObjectFactory.class == descriptor.getDependencyType() ||
ObjectProvider.class == descriptor.getDependencyType()) {
return new DependencyObjectProvider(descriptor, requestingBeanName);
}
else if (javaxInjectProviderClass == descriptor.getDependencyType()) {
return new Jsr330ProviderFactory().createDependencyProvider(descriptor, requestingBeanName);
}
else {
Object result = getAutowireCandidateResolver().getLazyResolutionProxyIfNecessary(
descriptor, requestingBeanName);
if (result == null) {
result = doResolveDependency(descriptor, requestingBeanName, autowiredBeanNames, typeConverter);
}
return result;
}
}
@Nullable
public Object doResolveDependency(DependencyDescriptor descriptor, @Nullable String beanName,
@Nullable Set<String> autowiredBeanNames, @Nullable TypeConverter typeConverter) throws BeansException {
InjectionPoint previousInjectionPoint = ConstructorResolver.setCurrentInjectionPoint(descriptor);
try {
Object shortcut = descriptor.resolveShortcut(this);
if (shortcut != null) {
return shortcut;
}
Class<?> type = descriptor.getDependencyType();
Object value = getAutowireCandidateResolver().getSuggestedValue(descriptor);
if (value != null) {
if (value instanceof String) {
String strVal = resolveEmbeddedValue((String) value);
BeanDefinition bd = (beanName != null && containsBean(beanName) ? getMergedBeanDefinition(beanName) : null);
value = evaluateBeanDefinitionString(strVal, bd);
}
TypeConverter converter = (typeConverter != null ? typeConverter : getTypeConverter());
return (descriptor.getField() != null ?
converter.convertIfNecessary(value, type, descriptor.getField()) :
converter.convertIfNecessary(value, type, descriptor.getMethodParameter()));
}
Object multipleBeans = resolveMultipleBeans(descriptor, beanName, autowiredBeanNames, typeConverter);
if (multipleBeans != null) {
return multipleBeans;
}
Map<String, Object> matchingBeans = findAutowireCandidates(beanName, type, descriptor);
if (matchingBeans.isEmpty()) {
if (isRequired(descriptor)) {
raiseNoMatchingBeanFound(type, descriptor.getResolvableType(), descriptor);
}
return null;
}
String autowiredBeanName;
Object instanceCandidate;
if (matchingBeans.size() > 1) {
autowiredBeanName = determineAutowireCandidate(matchingBeans, descriptor);
if (autowiredBeanName == null) {
if (isRequired(descriptor) || !indicatesMultipleBeans(type)) {
return descriptor.resolveNotUnique(type, matchingBeans);
}
else {
// In case of an optional Collection/Map, silently ignore a non-unique case:
// possibly it was meant to be an empty collection of multiple regular beans
// (before 4.3 in particular when we didn't even look for collection beans).
return null;
}
}
instanceCandidate = matchingBeans.get(autowiredBeanName);
}
else {
// We have exactly one match.
Map.Entry<String, Object> entry = matchingBeans.entrySet().iterator().next();
autowiredBeanName = entry.getKey();
instanceCandidate = entry.getValue();
}
if (autowiredBeanNames != null) {
autowiredBeanNames.add(autowiredBeanName);
}
if (instanceCandidate instanceof Class) {
instanceCandidate = descriptor.resolveCandidate(autowiredBeanName, type, this);
}
Object result = instanceCandidate;
if (result instanceof NullBean) {
if (isRequired(descriptor)) {
raiseNoMatchingBeanFound(type, descriptor.getResolvableType(), descriptor);
}
result = null;
}
if (!ClassUtils.isAssignableValue(type, result)) {
throw new BeanNotOfRequiredTypeException(autowiredBeanName, type, instanceCandidate.getClass());
}
return result;
}
finally {
ConstructorResolver.setCurrentInjectionPoint(previousInjectionPoint);
}
}
@Nullable
private Object resolveMultipleBeans(DependencyDescriptor descriptor, @Nullable String beanName,
@Nullable Set<String> autowiredBeanNames, @Nullable TypeConverter typeConverter) {
Class<?> type = descriptor.getDependencyType();
if (type.isArray()) {
Class<?> componentType = type.getComponentType();
ResolvableType resolvableType = descriptor.getResolvableType();
Class<?> resolvedArrayType = resolvableType.resolve();
if (resolvedArrayType != null && resolvedArrayType != type) {
type = resolvedArrayType;
componentType = resolvableType.getComponentType().resolve();
}
if (componentType == null) {
return null;
}
Map<String, Object> matchingBeans = findAutowireCandidates(beanName, componentType,
new MultiElementDescriptor(descriptor));
if (matchingBeans.isEmpty()) {
return null;
}
if (autowiredBeanNames != null) {
autowiredBeanNames.addAll(matchingBeans.keySet());
}
TypeConverter converter = (typeConverter != null ? typeConverter : getTypeConverter());
Object result = converter.convertIfNecessary(matchingBeans.values(), type);
if (getDependencyComparator() != null && result instanceof Object[]) {
Arrays.sort((Object[]) result, adaptDependencyComparator(matchingBeans));
}
return result;
}
else if (Collection.class.isAssignableFrom(type) && type.isInterface()) {
Class<?> elementType = descriptor.getResolvableType().asCollection().resolveGeneric();
if (elementType == null) {
return null;
}
Map<String, Object> matchingBeans = findAutowireCandidates(beanName, elementType,
new MultiElementDescriptor(descriptor));
if (matchingBeans.isEmpty()) {
return null;
}
if (autowiredBeanNames != null) {
autowiredBeanNames.addAll(matchingBeans.keySet());
}
TypeConverter converter = (typeConverter != null ? typeConverter : getTypeConverter());
Object result = converter.convertIfNecessary(matchingBeans.values(), type);
if (getDependencyComparator() != null && result instanceof List) {
((List<?>) result).sort(adaptDependencyComparator(matchingBeans));
}
return result;
}
else if (Map.class == type) {
ResolvableType mapType = descriptor.getResolvableType().asMap();
Class<?> keyType = mapType.resolveGeneric(0);
if (String.class != keyType) {
return null;
}
Class<?> valueType = mapType.resolveGeneric(1);
if (valueType == null) {
return null;
}
Map<String, Object> matchingBeans = findAutowireCandidates(beanName, valueType,
new MultiElementDescriptor(descriptor));
if (matchingBeans.isEmpty()) {
return null;
}
if (autowiredBeanNames != null) {
autowiredBeanNames.addAll(matchingBeans.keySet());
}
return matchingBeans;
}
else {
return null;
}
}
private boolean isRequired(DependencyDescriptor descriptor) {
return getAutowireCandidateResolver().isRequired(descriptor);
}
private boolean indicatesMultipleBeans(Class<?> type) {
return (type.isArray() || (type.isInterface() &&
(Collection.class.isAssignableFrom(type) || Map.class.isAssignableFrom(type))));
}
@Nullable
private Comparator<Object> adaptDependencyComparator(Map<String, Object> matchingBeans) {
Comparator<Object> comparator = getDependencyComparator();
if (comparator instanceof OrderComparator) {
return ((OrderComparator) comparator).withSourceProvider(
createFactoryAwareOrderSourceProvider(matchingBeans));
}
else {
return comparator;
}
}
private FactoryAwareOrderSourceProvider createFactoryAwareOrderSourceProvider(Map<String, Object> beans) {
IdentityHashMap<Object, String> instancesToBeanNames = new IdentityHashMap<>();
beans.forEach((beanName, instance) -> instancesToBeanNames.put(instance, beanName));
return new FactoryAwareOrderSourceProvider(instancesToBeanNames);
}
/**
* Find bean instances that match the required type.
* Called during autowiring for the specified bean.
* @param beanName the name of the bean that is about to be wired
* @param requiredType the actual type of bean to look for
* (may be an array component type or collection element type)
* @param descriptor the descriptor of the dependency to resolve
* @return a Map of candidate names and candidate instances that match
* the required type (never {@code null})
* @throws BeansException in case of errors
* @see #autowireByType
* @see #autowireConstructor
*/
protected Map<String, Object> findAutowireCandidates(
@Nullable String beanName, Class<?> requiredType, DependencyDescriptor descriptor) {
String[] candidateNames = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(
this, requiredType, true, descriptor.isEager());
Map<String, Object> result = new LinkedHashMap<>(candidateNames.length);
for (Class<?> autowiringType : this.resolvableDependencies.keySet()) {
if (autowiringType.isAssignableFrom(requiredType)) {
Object autowiringValue = this.resolvableDependencies.get(autowiringType);
autowiringValue = AutowireUtils.resolveAutowiringValue(autowiringValue, requiredType);
if (requiredType.isInstance(autowiringValue)) {
result.put(ObjectUtils.identityToString(autowiringValue), autowiringValue);
break;
}
}
}
for (String candidate : candidateNames) {
if (!isSelfReference(beanName, candidate) && isAutowireCandidate(candidate, descriptor)) {
addCandidateEntry(result, candidate, descriptor, requiredType);
}
}
if (result.isEmpty() && !indicatesMultipleBeans(requiredType)) {
// Consider fallback matches if the first pass failed to find anything...
DependencyDescriptor fallbackDescriptor = descriptor.forFallbackMatch();
for (String candidate : candidateNames) {
if (!isSelfReference(beanName, candidate) && isAutowireCandidate(candidate, fallbackDescriptor)) {
addCandidateEntry(result, candidate, descriptor, requiredType);
}
}
if (result.isEmpty()) {
// Consider self references as a final pass...
// but in the case of a dependency collection, not the very same bean itself.
for (String candidate : candidateNames) {
if (isSelfReference(beanName, candidate) &&
(!(descriptor instanceof MultiElementDescriptor) || !beanName.equals(candidate)) &&
isAutowireCandidate(candidate, fallbackDescriptor)) {
addCandidateEntry(result, candidate, descriptor, requiredType);
}
}
}
}
return result;
}
/**
* Add an entry to the candidate map: a bean instance if available or just the resolved
* type, preventing early bean initialization ahead of primary candidate selection.
*/
private void addCandidateEntry(Map<String, Object> candidates, String candidateName,
DependencyDescriptor descriptor, Class<?> requiredType) {
if (descriptor instanceof MultiElementDescriptor || containsSingleton(candidateName)) {
Object beanInstance = descriptor.resolveCandidate(candidateName, requiredType, this);
candidates.put(candidateName, (beanInstance instanceof NullBean ? null : beanInstance));
}
else {
candidates.put(candidateName, getType(candidateName));
}
}
/**
* Determine the autowire candidate in the given set of beans.
* <p>Looks for {@code @Primary} and {@code @Priority} (in that order).
* @param candidates a Map of candidate names and candidate instances
* that match the required type, as returned by {@link #findAutowireCandidates}
* @param descriptor the target dependency to match against
* @return the name of the autowire candidate, or {@code null} if none found
*/
@Nullable
protected String determineAutowireCandidate(Map<String, Object> candidates, DependencyDescriptor descriptor) {
Class<?> requiredType = descriptor.getDependencyType();
String primaryCandidate = determinePrimaryCandidate(candidates, requiredType);
if (primaryCandidate != null) {
return primaryCandidate;
}
String priorityCandidate = determineHighestPriorityCandidate(candidates, requiredType);
if (priorityCandidate != null) {
return priorityCandidate;
}
// Fallback
for (Map.Entry<String, Object> entry : candidates.entrySet()) {
String candidateName = entry.getKey();
Object beanInstance = entry.getValue();
if ((beanInstance != null && this.resolvableDependencies.containsValue(beanInstance)) ||
matchesBeanName(candidateName, descriptor.getDependencyName())) {
return candidateName;
}
}
return null;
}
/**
* Determine the primary candidate in the given set of beans.
* @param candidates a Map of candidate names and candidate instances
* (or candidate classes if not created yet) that match the required type
* @param requiredType the target dependency type to match against
* @return the name of the primary candidate, or {@code null} if none found
* @see #isPrimary(String, Object)
*/
@Nullable
protected String determinePrimaryCandidate(Map<String, Object> candidates, Class<?> requiredType) {
String primaryBeanName = null;
for (Map.Entry<String, Object> entry : candidates.entrySet()) {
String candidateBeanName = entry.getKey();
Object beanInstance = entry.getValue();
if (isPrimary(candidateBeanName, beanInstance)) {
if (primaryBeanName != null) {
boolean candidateLocal = containsBeanDefinition(candidateBeanName);
boolean primaryLocal = containsBeanDefinition(primaryBeanName);
if (candidateLocal && primaryLocal) {
throw new NoUniqueBeanDefinitionException(requiredType, candidates.size(),
"more than one 'primary' bean found among candidates: " + candidates.keySet());
}
else if (candidateLocal) {
primaryBeanName = candidateBeanName;
}
}
else {
primaryBeanName = candidateBeanName;
}
}
}
return primaryBeanName;
}
/**
* Determine the candidate with the highest priority in the given set of beans.
* <p>Based on {@code @javax.annotation.Priority}. As defined by the related
* {@link org.springframework.core.Ordered} interface, the lowest value has
* the highest priority.
* @param candidates a Map of candidate names and candidate instances
* (or candidate classes if not created yet) that match the required type
* @param requiredType the target dependency type to match against
* @return the name of the candidate with the highest priority,
* or {@code null} if none found
* @see #getPriority(Object)
*/
@Nullable
protected String determineHighestPriorityCandidate(Map<String, Object> candidates, Class<?> requiredType) {
String highestPriorityBeanName = null;
Integer highestPriority = null;
for (Map.Entry<String, Object> entry : candidates.entrySet()) {
String candidateBeanName = entry.getKey();
Object beanInstance = entry.getValue();
if (beanInstance != null) {
Integer candidatePriority = getPriority(beanInstance);
if (candidatePriority != null) {
if (highestPriorityBeanName != null) {
if (candidatePriority.equals(highestPriority)) {
throw new NoUniqueBeanDefinitionException(requiredType, candidates.size(),
"Multiple beans found with the same priority ('" + highestPriority +
"') among candidates: " + candidates.keySet());
}
else if (candidatePriority < highestPriority) {
highestPriorityBeanName = candidateBeanName;
highestPriority = candidatePriority;
}
}
else {
highestPriorityBeanName = candidateBeanName;
highestPriority = candidatePriority;
}
}
}
}
return highestPriorityBeanName;
}
/**
* Return whether the bean definition for the given bean name has been
* marked as a primary bean.
* @param beanName the name of the bean
* @param beanInstance the corresponding bean instance (can be null)
* @return whether the given bean qualifies as primary
*/
protected boolean isPrimary(String beanName, Object beanInstance) {
if (containsBeanDefinition(beanName)) {
return getMergedLocalBeanDefinition(beanName).isPrimary();
}
BeanFactory parent = getParentBeanFactory();
return (parent instanceof DefaultListableBeanFactory &&
((DefaultListableBeanFactory) parent).isPrimary(beanName, beanInstance));
}
/**
* Return the priority assigned for the given bean instance by
* the {@code javax.annotation.Priority} annotation.
* <p>The default implementation delegates to the specified
* {@link #setDependencyComparator dependency comparator}, checking its
* {@link OrderComparator#getPriority method} if it is an extension of
* Spring's common {@link OrderComparator} - typically, an
* {@link org.springframework.core.annotation.AnnotationAwareOrderComparator}.
* If no such comparator is present, this implementation returns {@code null}.
* @param beanInstance the bean instance to check (can be {@code null})
* @return the priority assigned to that bean or {@code null} if none is set
*/
@Nullable
protected Integer getPriority(Object beanInstance) {
Comparator<Object> comparator = getDependencyComparator();
if (comparator instanceof OrderComparator) {
return ((OrderComparator) comparator).getPriority(beanInstance);
}
return null;
}
/**
* Determine whether the given candidate name matches the bean name or the aliases
* stored in this bean definition.
*/
protected boolean matchesBeanName(String beanName, @Nullable String candidateName) {
return (candidateName != null &&
(candidateName.equals(beanName) || ObjectUtils.containsElement(getAliases(beanName), candidateName)));
}
/**
* Determine whether the given beanName/candidateName pair indicates a self reference,
* i.e. whether the candidate points back to the original bean or to a factory method
* on the original bean.
*/
private boolean isSelfReference(@Nullable String beanName, @Nullable String candidateName) {
return (beanName != null && candidateName != null &&
(beanName.equals(candidateName) || (containsBeanDefinition(candidateName) &&
beanName.equals(getMergedLocalBeanDefinition(candidateName).getFactoryBeanName()))));
}
/**
* Raise a NoSuchBeanDefinitionException or BeanNotOfRequiredTypeException
* for an unresolvable dependency.
*/
private void raiseNoMatchingBeanFound(
Class<?> type, ResolvableType resolvableType, DependencyDescriptor descriptor) throws BeansException {
checkBeanNotOfRequiredType(type, descriptor);
throw new NoSuchBeanDefinitionException(resolvableType,
"expected at least 1 bean which qualifies as autowire candidate. " +
"Dependency annotations: " + ObjectUtils.nullSafeToString(descriptor.getAnnotations()));
}
/**
* Raise a BeanNotOfRequiredTypeException for an unresolvable dependency, if applicable,
* i.e. if the target type of the bean would match but an exposed proxy doesn't.
*/
private void checkBeanNotOfRequiredType(Class<?> type, DependencyDescriptor descriptor) {
for (String beanName : this.beanDefinitionNames) {
RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
Class<?> targetType = mbd.getTargetType();
if (targetType != null && type.isAssignableFrom(targetType) &&
isAutowireCandidate(beanName, mbd, descriptor, getAutowireCandidateResolver())) {
// Probably a proxy interfering with target type match -> throw meaningful exception.
Object beanInstance = getSingleton(beanName, false);
Class<?> beanType = (beanInstance != null && beanInstance.getClass() != NullBean.class) ?
beanInstance.getClass() : predictBeanType(beanName, mbd);
if (beanType != null && !type.isAssignableFrom(beanType)) {
throw new BeanNotOfRequiredTypeException(beanName, type, beanType);
}
}
}
BeanFactory parent = getParentBeanFactory();
if (parent instanceof DefaultListableBeanFactory) {
((DefaultListableBeanFactory) parent).checkBeanNotOfRequiredType(type, descriptor);
}
}
/**
* Create an {@link Optional} wrapper for the specified dependency.
*/
private Optional<?> createOptionalDependency(
DependencyDescriptor descriptor, @Nullable String beanName, final Object... args) {
DependencyDescriptor descriptorToUse = new NestedDependencyDescriptor(descriptor) {
@Override
public boolean isRequired() {
return false;
}
@Override
public Object resolveCandidate(String beanName, Class<?> requiredType, BeanFactory beanFactory) {
return (!ObjectUtils.isEmpty(args) ? beanFactory.getBean(beanName, args) :
super.resolveCandidate(beanName, requiredType, beanFactory));
}
};
return Optional.ofNullable(doResolveDependency(descriptorToUse, beanName, null, null));
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder(ObjectUtils.identityToString(this));
sb.append(": defining beans [");
sb.append(StringUtils.collectionToCommaDelimitedString(this.beanDefinitionNames));
sb.append("]; ");
BeanFactory parent = getParentBeanFactory();
if (parent == null) {
sb.append("root of factory hierarchy");
}
else {
sb.append("parent: ").append(ObjectUtils.identityToString(parent));
}
return sb.toString();
}
//---------------------------------------------------------------------
// Serialization support
//---------------------------------------------------------------------
private void readObject(ObjectInputStream ois) throws IOException, ClassNotFoundException {
throw new NotSerializableException("DefaultListableBeanFactory itself is not deserializable - " +
"just a SerializedBeanFactoryReference is");
}
protected Object writeReplace() throws ObjectStreamException {
if (this.serializationId != null) {
return new SerializedBeanFactoryReference(this.serializationId);
}
else {
throw new NotSerializableException("DefaultListableBeanFactory has no serialization id");
}
}
/**
* Minimal id reference to the factory.
* Resolved to the actual factory instance on deserialization.
*/
private static class SerializedBeanFactoryReference implements Serializable {
private final String id;
public SerializedBeanFactoryReference(String id) {
this.id = id;
}
private Object readResolve() {
Reference<?> ref = serializableFactories.get(this.id);
if (ref != null) {
Object result = ref.get();
if (result != null) {
return result;
}
}
// Lenient fallback: dummy factory in case of original factory not found...
return new DefaultListableBeanFactory();
}
}
/**
* Serializable ObjectFactory/ObjectProvider for lazy resolution of a dependency.
*/
private class DependencyObjectProvider implements ObjectProvider<Object>, Serializable {
private final DependencyDescriptor descriptor;
private final boolean optional;
@Nullable
private final String beanName;
public DependencyObjectProvider(DependencyDescriptor descriptor, @Nullable String beanName) {
this.descriptor = new NestedDependencyDescriptor(descriptor);
this.optional = (this.descriptor.getDependencyType() == Optional.class);
this.beanName = beanName;
}
@Override
public Object getObject() throws BeansException {
if (this.optional) {
return createOptionalDependency(this.descriptor, this.beanName);
}
else {
Object result = doResolveDependency(this.descriptor, this.beanName, null, null);
if (result == null) {
throw new NoSuchBeanDefinitionException(this.descriptor.getResolvableType());
}
return result;
}
}
@Override
public Object getObject(final Object... args) throws BeansException {
if (this.optional) {
return createOptionalDependency(this.descriptor, this.beanName, args);
}
else {
DependencyDescriptor descriptorToUse = new DependencyDescriptor(descriptor) {
@Override
public Object resolveCandidate(String beanName, Class<?> requiredType, BeanFactory beanFactory) {
return beanFactory.getBean(beanName, args);
}
};
Object result = doResolveDependency(descriptorToUse, this.beanName, null, null);
if (result == null) {
throw new NoSuchBeanDefinitionException(this.descriptor.getResolvableType());
}
return result;
}
}
@Override
@Nullable
public Object getIfAvailable() throws BeansException {
if (this.optional) {
return createOptionalDependency(this.descriptor, this.beanName);
}
else {
DependencyDescriptor descriptorToUse = new DependencyDescriptor(descriptor) {
@Override
public boolean isRequired() {
return false;
}
};
return doResolveDependency(descriptorToUse, this.beanName, null, null);
}
}
@Override
@Nullable
public Object getIfUnique() throws BeansException {
DependencyDescriptor descriptorToUse = new DependencyDescriptor(descriptor) {
@Override
public boolean isRequired() {
return false;
}
@Override
@Nullable
public Object resolveNotUnique(Class<?> type, Map<String, Object> matchingBeans) {
return null;
}
};
if (this.optional) {
return createOptionalDependency(descriptorToUse, this.beanName);
}
else {
return doResolveDependency(descriptorToUse, this.beanName, null, null);
}
}
@Nullable
protected Object getValue() throws BeansException {
if (this.optional) {
return createOptionalDependency(this.descriptor, this.beanName);
}
else {
return doResolveDependency(this.descriptor, this.beanName, null, null);
}
}
}
/**
* Serializable ObjectFactory for lazy resolution of a dependency.
*/
private class Jsr330DependencyProvider extends DependencyObjectProvider implements Provider<Object> {
public Jsr330DependencyProvider(DependencyDescriptor descriptor, @Nullable String beanName) {
super(descriptor, beanName);
}
@Override
@Nullable
public Object get() throws BeansException {
return getValue();
}
}
/**
* Separate inner class for avoiding a hard dependency on the {@code javax.inject} API.
*/
private class Jsr330ProviderFactory {
public Object createDependencyProvider(DependencyDescriptor descriptor, @Nullable String beanName) {
return new Jsr330DependencyProvider(descriptor, beanName);
}
}
/**
* An {@link org.springframework.core.OrderComparator.OrderSourceProvider} implementation
* that is aware of the bean metadata of the instances to sort.
* <p>Lookup for the method factory of an instance to sort, if any, and let the
* comparator retrieve the {@link org.springframework.core.annotation.Order}
* value defined on it. This essentially allows for the following construct:
*/
private class FactoryAwareOrderSourceProvider implements OrderComparator.OrderSourceProvider {
private final Map<Object, String> instancesToBeanNames;
public FactoryAwareOrderSourceProvider(Map<Object, String> instancesToBeanNames) {
this.instancesToBeanNames = instancesToBeanNames;
}
@Override
@Nullable
public Object getOrderSource(Object obj) {
RootBeanDefinition beanDefinition = getRootBeanDefinition(this.instancesToBeanNames.get(obj));
if (beanDefinition == null) {
return null;
}
List<Object> sources = new ArrayList<>(2);
Method factoryMethod = beanDefinition.getResolvedFactoryMethod();
if (factoryMethod != null) {
sources.add(factoryMethod);
}
Class<?> targetType = beanDefinition.getTargetType();
if (targetType != null && targetType != obj.getClass()) {
sources.add(targetType);
}
return sources.toArray();
}
@Nullable
private RootBeanDefinition getRootBeanDefinition(@Nullable String beanName) {
if (beanName != null && containsBeanDefinition(beanName)) {
BeanDefinition bd = getMergedBeanDefinition(beanName);
if (bd instanceof RootBeanDefinition) {
return (RootBeanDefinition) bd;
}
}
return null;
}
}
private static class NestedDependencyDescriptor extends DependencyDescriptor {
public NestedDependencyDescriptor(DependencyDescriptor original) {
super(original);
increaseNestingLevel();
}
}
private static class MultiElementDescriptor extends NestedDependencyDescriptor {
public MultiElementDescriptor(DependencyDescriptor original) {
super(original);
}
}
}
下面是XmlBeanFactory在使用过程中涉及到的类的关系图：
BeanDefinition的加载、解析、注册过程分析：XmlBeanDefinitionReader
XmlBeanDefinitionReader.java
public int loadBeanDefinitions(Resource resource) throws BeanDefinitionStoreException {
//loadBeanDefinitions的具体实现，而EncodedResource主要用于对资源文件的处理，而其主要实现方法getReader（）在下面有所介绍
return loadBeanDefinitions(new EncodedResource(resource));
}
public int loadBeanDefinitions(EncodedResource encodedResource) throws BeanDefinitionStoreException {
Assert.notNull(encodedResource, "EncodedResource must not be null");
if (logger.isInfoEnabled()) {
logger.info("Loading XML bean definitions from " + encodedResource.getResource());
}
//通过属性来记录已经加载的资源
Set<EncodedResource> currentResources = this.resourcesCurrentlyBeingLoaded.get();
if (currentResources == null) {
currentResources = new HashSet<EncodedResource>(4);
this.resourcesCurrentlyBeingLoaded.set(currentResources);
}
if (!currentResources.add(encodedResource)) {
throw new BeanDefinitionStoreException(
"Detected cyclic loading of " + encodedResource + " - check your import definitions!");
}
// 调用DefaultResourceLoader的getResources方法完成具体的Resource定位
try {
//从EncodedResource中获取已经封装的Resource对象并再次从Resource中获取inputStream
InputStream inputStream = encodedResource.getResource().getInputStream();
try {
InputSource inputSource = new InputSource(inputStream);
if (encodedResource.getEncoding() != null) {
inputSource.setEncoding(encodedResource.getEncoding());
}
return doLoadBeanDefinitions(inputSource, encodedResource.getResource()); //真正的逻辑核心
}
finally {
inputStream.close(); //关闭inputStream
}
}
catch (IOException ex) {
throw new BeanDefinitionStoreException(
"IOException parsing XML document from " + encodedResource.getResource(), ex);
}
finally {
currentResources.remove(encodedResource);
if (currentResources.isEmpty()) {
this.resourcesCurrentlyBeingLoaded.remove();
}
}
}
/**
* 真正的核心处理部分
* 如果不考虑冗余的代码，其实只做三件事：
* 1.获取XML文件的验证模式
* 2.由DefaultDocumentLoader加载XML，并获取Document.
* 3.返回的Document，注册Bean
*/
protected int doLoadBeanDefinitions(InputSource inputSource, Resource resource)
throws BeanDefinitionStoreException {
try {
// 取得XML文件的Document对象, 这个解析过程由DefaultDocumentLoader完成
Document doc = doLoadDocument(inputSource, resource);
// 启动对BeanDefinition解析的详细过程, 解析过程中会使用到Spring的Bean配置规则
return registerBeanDefinitions(doc, resource);
}
catch (BeanDefinitionStoreException ex) {
throw ex;
}
catch (SAXParseException ex) {
throw new XmlBeanDefinitionStoreException(resource.getDescription(),
"Line " + ex.getLineNumber() + " in XML document from " + resource + " is invalid", ex);
}
catch (SAXException ex) {
throw new XmlBeanDefinitionStoreException(resource.getDescription(),
"XML document from " + resource + " is invalid", ex);
}
catch (ParserConfigurationException ex) {
throw new BeanDefinitionStoreException(resource.getDescription(),
"Parser configuration exception parsing XML from " + resource, ex);
}
catch (IOException ex) {
throw new BeanDefinitionStoreException(resource.getDescription(),
"IOException parsing XML document from " + resource, ex);
}
catch (Throwable ex) {
throw new BeanDefinitionStoreException(resource.getDescription(),
"Unexpected exception parsing XML document from " + resource, ex);
}
}
protected Document doLoadDocument(InputSource inputSource, Resource resource) throws Exception {
//loadDocument直接用于注册Document，getValidationModeForResource方法作用于XML的加载
return this.documentLoader.loadDocument(inputSource, getEntityResolver(), this.errorHandler,
getValidationModeForResource(resource), isNamespaceAware());
}
:-: Xml文件验证
获取Xml文件的验证模式，一般分为两步：首先，是Xml文件验证，然后是验证模式的读取。
Spring的默认配置文件applicationContext.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans
xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-4.0.xsd"> //XSD方式，用于验证XML文件的正确性
<bean id="..">...</bean>
</beans>
常用的Xml文件的验证方式有两种：DTD和XSD，DTD现在基本不用了，而上图中的spring-beans-4.0.xsd对应在源码中的org.springframework.beans.factory.xml.spring-beans-4.0.xsd。
protected Document doLoadDocument(InputSource inputSource, Resource resource) throws Exception {
//loadDocument直接用于注册Document，getValidationModeForResource方法作用于XML的加载
return this.documentLoader.loadDocument(inputSource, getEntityResolver(), this.errorHandler,
getValidationModeForResource(resource), isNamespaceAware());
}
XmlBeanDefinitionReader.java
public static final int VALIDATION_AUTO = XmlValidationModeDetector.VALIDATION_AUTO;
public static final int VALIDATION_XSD = XmlValidationModeDetector.VALIDATION_XSD;
protected int getValidationModeForResource(Resource resource) {
int validationModeToUse = getValidationMode();
//如果手动指定了验证模式则使用指定的验证模式
if (validationModeToUse != VALIDATION_AUTO) {
return validationModeToUse;
}
//如果没有指定，则自动检测
int detectedMode = detectValidationMode(resource); //自动检测主要是在detectValidationMode（Resource resource）完成的
if (detectedMode != VALIDATION_AUTO) {
return detectedMode;
}
return VALIDATION_XSD;
}
protected int detectValidationMode(Resource resource) {
if (resource.isOpen()) {
throw new BeanDefinitionStoreException(
"Passed-in Resource [" + resource + "] contains an open stream: " +
"cannot determine validation mode automatically. Either pass in a Resource " +
"that is able to create fresh streams, or explicitly specify the validationMode " +
"on your XmlBeanDefinitionReader instance.");
}
InputStream inputStream;
try {
inputStream = resource.getInputStream();
}
catch (IOException ex) {
throw new BeanDefinitionStoreException(
"Unable to determine validation mode for [" + resource + "]: cannot open InputStream. " +
"Did you attempt to load directly from a SAX InputSource without specifying the " +
"validationMode on your XmlBeanDefinitionReader instance?", ex);
}
try {
return this.validationModeDetector.detectValidationMode(inputStream); //自动检测则是给detectValidationMode完成的
}
catch (IOException ex) {
throw new BeanDefinitionStoreException("Unable to determine validation mode for [" +
resource + "]: an error occurred whilst reading from the InputStream.", ex);
}
}
XmlValidationModeDetecor.java
public static final int VALIDATION_NONE = 0;
public static final int VALIDATION_AUTO = 1;
public static final int VALIDATION_DTD = 2;
public static final int VALIDATION_XSD = 3;
private static final String DOCTYPE = "DOCTYPE";
public int detectValidationMode(InputStream inputStream) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
try {
boolean isDtdValidated = false;
String content;
while ((content = reader.readLine()) != null) {
content = consumeCommentTokens(content);
//空或注释略过
if (this.inComment || !StringUtils.hasText(content)) {
continue;
}
if (hasDoctype(content)) {
isDtdValidated = true;
break;
}
//读取<前的信息
if (hasOpeningTag(content)) {
break;
}
}
return (isDtdValidated ? VALIDATION_DTD : VALIDATION_XSD);
}
catch (CharConversionException ex) {
return VALIDATION_AUTO;
}
finally {
reader.close();
}
}
private boolean hasDoctype(String content) {
return content.contains(DOCTYPE);
}
private boolean hasOpeningTag(String content) {
if (this.inComment) {
return false;
}
int openTagIndex = content.indexOf('<');
return (openTagIndex > -1 && (content.length() > openTagIndex + 1) &&
Character.isLetter(content.charAt(openTagIndex + 1)));
}
:-: 获取Document
通过以上的验证准备，就可以进行加载Xml文件了，而XmlDefinitionReader并没有自己去完成，而是交给了DocumentLoader接口去完成，其实现类是DefaultDocumentLoader，调用DefaultDocumentLoader.loadDocument()方法。
protected Document doLoadDocument(InputSource inputSource, Resource resource) throws Exception {
//loadDocument直接用于注册Document，getValidationModeForResource方法作用于XML的加载
return this.documentLoader.loadDocument(inputSource, getEntityResolver(), this.errorHandler,
getValidationModeForResource(resource), isNamespaceAware());
}
XmlBeanDefinitionReader.java
private DocumentLoader documentLoader = new DefaultDocumentLoader();
//EntityResolver主要用于处理前面提到的DTD方法的处理
protected EntityResolver getEntityResolver() {
if (this.entityResolver == null) {
ResourceLoader resourceLoader = getResourceLoader();
if (resourceLoader != null) {
this.entityResolver = new ResourceEntityResolver(resourceLoader);
}
else {
this.entityResolver = new DelegatingEntityResolver(getBeanClassLoader());
}
}
return this.entityResolver;
}
DefaultDocumentLoader.java
public Document loadDocument(InputSource inputSource, EntityResolver entityResolver,
ErrorHandler errorHandler, int validationMode, boolean namespaceAware) throws Exception {
DocumentBuilderFactory factory = createDocumentBuilderFactory(validationMode, namespaceAware);
if (logger.isDebugEnabled()) {
logger.debug("Using JAXP provider [" + factory.getClass().getName() + "]");
}
DocumentBuilder builder = createDocumentBuilder(factory, entityResolver, errorHandler);
return builder.parse(inputSource);
}
:-: BeanDefinition的解析
Beandefinition的注册过程其实就是把Xml中定义的Bean在Ioc容器中转化为一个Spring内部表示的数据结构的过程。Ioc容器对Bean的管理和依赖注入的实现，都是通过对其持有的BeanDefinition进行各种相关的操作来完成的。这些BeanDedinition数据在Ioc容器中通过一个HashMap来维护。
XmlBeanDefinitionReader.java
private Class<?> documentReaderClass = DefaultBeanDefinitionDocumentReader.class;
public int registerBeanDefinitions(Document doc, Resource resource) throws BeanDefinitionStoreException {
// 得到BeanDefinitionDocumentReader来对XML的BeanDefinition进行解析
BeanDefinitionDocumentReader documentReader = createBeanDefinitionDocumentReader();
int countBefore = getRegistry().getBeanDefinitionCount();
// 具体的解析过程在BeanDefinitionDocumentReader的registerBeanDefinitions方法中完成
documentReader.registerBeanDefinitions(doc, createReaderContext(resource));
return getRegistry().getBeanDefinitionCount() - countBefore;
}
protected BeanDefinitionDocumentReader createBeanDefinitionDocumentReader() {
return BeanDefinitionDocumentReader.class.cast(BeanUtils.instantiateClass(this.documentReaderClass));
}
DefaultBeanDefinitionDocumentReader.java
public static final String BEAN_ELEMENT = BeanDefinitionParserDelegate.BEAN_ELEMENT;
public static final String NESTED_BEANS_ELEMENT = "beans";
public static final String ALIAS_ELEMENT = "alias";
public static final String ALIAS_ATTRIBUTE = "alias";
public void registerBeanDefinitions(Document doc, XmlReaderContext readerContext) {
this.readerContext = readerContext;
logger.debug("Loading bean definitions");
Element root = doc.getDocumentElement(); // 获得Document的根元素
doRegisterBeanDefinitions(root);
}
protected void doRegisterBeanDefinitions(Element root) {
BeanDefinitionParserDelegate parent = this.delegate;
this.delegate = createDelegate(getReaderContext(), root, parent);
if (this.delegate.isDefaultNamespace(root)) {
String profileSpec = root.getAttribute(PROFILE_ATTRIBUTE);
if (StringUtils.hasText(profileSpec)) {
String[] specifiedProfiles = StringUtils.tokenizeToStringArray(
profileSpec, BeanDefinitionParserDelegate.MULTI_VALUE_ATTRIBUTE_DELIMITERS);
if (!getReaderContext().getEnvironment().acceptsProfiles(specifiedProfiles)) {
return;
}
}
}
preProcessXml(root); // 解析Bean定义之前, 增强解析过程的可扩展性
parseBeanDefinitions(root, this.delegate); // 从Document的根元素开始进行Bean定义的Document对象
postProcessXml(root); // 解析Bean定义之前, 增强解析过程的可扩展性
this.delegate = parent;
}
protected void parseBeanDefinitions(Element root, BeanDefinitionParserDelegate delegate) {
if (delegate.isDefaultNamespace(root)) {
NodeList nl = root.getChildNodes(); // 获取Document对象根元素的所有子节点并循环解析
for (int i = 0; i < nl.getLength(); i++) {
Node node = nl.item(i);
if (node instanceof Element) {
Element ele = (Element) node;
if (delegate.isDefaultNamespace(ele)) {
parseDefaultElement(ele, delegate); // 解析Spring的Bean规则默认元素节点
}
else {
delegate.parseCustomElement(ele); // 解析自定义元素节点
}
}
}
}
else {
delegate.parseCustomElement(root); // 解析自定义元素根节点
}
}
private void parseDefaultElement(Element ele, BeanDefinitionParserDelegate delegate) {
if (delegate.nodeNameEquals(ele, IMPORT_ELEMENT)) { // 解析import元素
importBeanDefinitionResource(ele);
}
else if (delegate.nodeNameEquals(ele, ALIAS_ELEMENT)) { // 解析alias元素
processAliasRegistration(ele);
}
else if (delegate.nodeNameEquals(ele, BEAN_ELEMENT)) { // 解析bean元素
processBeanDefinition(ele, delegate);
}
else if (delegate.nodeNameEquals(ele, NESTED_BEANS_ELEMENT)) { // 解析内嵌beans元素, 作为根节点递归解析
doRegisterBeanDefinitions(ele);
}
}
直接从代码上就可以看出来，Spring首先获取Document的根元素（一般为<beans/>）,然后获取根节点的所有子节点并循环解析这些子节点；如果子节点在Spring默认的命名空间内，则按照Spring Bean定义规则来解析，否则按照自定义的节点解析。
DefaultBeanDefinitionDocumentReader.java
protected void processBeanDefinition(Element ele, BeanDefinitionParserDelegate delegate) {
// 具体的解析委托给BeanDefinitionParserDelegate来完成
// BeanDefinitionHolder是BeanDefinition的封装类, 封装了BeanDefinition、Bean的名字和别名, 用它来完成向IoC容器注册.
BeanDefinitionHolder bdHolder = delegate.parseBeanDefinitionElement(ele);
if (bdHolder != null) {
bdHolder = delegate.decorateBeanDefinitionIfRequired(ele, bdHolder);
try {
BeanDefinitionReaderUtils.registerBeanDefinition(bdHolder, getReaderContext().getRegistry());
}
catch (BeanDefinitionStoreException ex) {
getReaderContext().error("Failed to register bean definition with name '" +
bdHolder.getBeanName() + "'", ele, ex);
}
getReaderContext().fireComponentRegistered(new BeanComponentDefinition(bdHolder));
}
}
BeanDefinotionParseDelegate.java
public BeanDefinitionHolder parseBeanDefinitionElement(Element ele) {
return parseBeanDefinitionElement(ele, null);
}
public BeanDefinitionHolder parseBeanDefinitionElement(Element ele, BeanDefinition containingBean) {
// 解析Bean定义资源文件中的<Bean>元素，主要处理<Bean>元素的id，name和aliase属性
String id = ele.getAttribute(ID_ATTRIBUTE);
String nameAttr = ele.getAttribute(NAME_ATTRIBUTE);
List<String> aliases = new ArrayList<String>();
if (StringUtils.hasLength(nameAttr)) {
String[] nameArr = StringUtils.tokenizeToStringArray(nameAttr, MULTI_VALUE_ATTRIBUTE_DELIMITERS);
aliases.addAll(Arrays.asList(nameArr));
}
String beanName = id;
// 如果<Bean>元素中没有配置id属性时, 将别名中的第一个值赋值给beanName
if (!StringUtils.hasText(beanName) && !aliases.isEmpty()) {
beanName = aliases.remove(0);
if (logger.isDebugEnabled()) {
logger.debug("No XML 'id' specified - using '" + beanName +
"' as bean name and " + aliases + " as aliases");
}
}
if (containingBean == null) {
checkNameUniqueness(beanName, aliases, ele);
}
// 对<bean>元素进行详细解析
AbstractBeanDefinition beanDefinition = parseBeanDefinitionElement(ele, beanName, containingBean);
if (beanDefinition != null) {
if (!StringUtils.hasText(beanName)) {
try {
if (containingBean != null) {
beanName = BeanDefinitionReaderUtils.generateBeanName(
beanDefinition, this.readerContext.getRegistry(), true);
}
else {
beanName = this.readerContext.generateBeanName(beanDefinition);
//为解析的Bean使用别名注册时, 为了向后兼容（Spring1.2/2.0给别名添加类名后缀）
String beanClassName = beanDefinition.getBeanClassName();
if (beanClassName != null &&
beanName.startsWith(beanClassName) && beanName.length() > beanClassName.length() &&
!this.readerContext.getRegistry().isBeanNameInUse(beanClassName)) {
aliases.add(beanClassName);
}
}
if (logger.isDebugEnabled()) {
logger.debug("Neither XML 'id' nor 'name' specified - " +
"using generated bean name [" + beanName + "]");
}
}
catch (Exception ex) {
error(ex.getMessage(), ele);
return null;
}
}
String[] aliasesArray = StringUtils.toStringArray(aliases);
return new BeanDefinitionHolder(beanDefinition, beanName, aliasesArray);
}
return null;
}
public AbstractBeanDefinition parseBeanDefinitionElement(
Element ele, String beanName, BeanDefinition containingBean) {
this.parseState.push(new BeanEntry(beanName));
// 这里只读取<Bean>元素中配置的class名字, 然后载入到BeanDefinition中去
// 只是记录配置的class名字, 并不实例化, 对象的实例化在依赖注入时完成
String className = null;
if (ele.hasAttribute(CLASS_ATTRIBUTE)) {
className = ele.getAttribute(CLASS_ATTRIBUTE).trim();
}
try {
String parent = null;
if (ele.hasAttribute(PARENT_ATTRIBUTE)) {
parent = ele.getAttribute(PARENT_ATTRIBUTE);
}
// 根据<Bean>元素配置的class名称和parent属性值创建BeanDefinition, 为载入Bean定义信息做准备
AbstractBeanDefinition bd = createBeanDefinition(className, parent);
// 对当前<Bean>元素中配置的一些属性进行解析, 如singleton、abstract等
parseBeanDefinitionAttributes(ele, beanName, containingBean, bd);
bd.setDescription(DomUtils.getChildElementValueByTagName(ele, DESCRIPTION_ELEMENT));
// 对<Bean>元素的meta(元数据)、lookup-method、replaced-method等子元素进行解析
parseMetaElements(ele, bd);
parseLookupOverrideSubElements(ele, bd.getMethodOverrides());
parseReplacedMethodSubElements(ele, bd.getMethodOverrides());
parseConstructorArgElements(ele, bd); // 解析<Bean>元素的构造方法参数
parsePropertyElements(ele, bd); // 解析<Bean>元素的<property>设置
parseQualifierElements(ele, bd);
bd.setResource(this.readerContext.getResource());
bd.setSource(extractSource(ele));
return bd;
}
catch (ClassNotFoundException ex) {
error("Bean class [" + className + "] not found", ele, ex);
}
catch (NoClassDefFoundError err) {
error("Class that bean class [" + className + "] depends on not found", ele, err);
}
catch (Throwable ex) {
error("Unexpected failure during bean definition parsing", ele, ex);
}
finally {
this.parseState.pop();
}
return null;
}
<bean>元素解析已经完了，而<bean>元素属性及其子元素的解析顺序为：
1，解析<bean>元素的属性。
2，解析<description>子元素。
3，解析<meta>子元素。
4，解析<lookup-method/>子元素。
5，解析<replaced-method>子元素。
6，解析<constructor-arg>子元素。
7，解析<property>子元素。
8，解析<qualifier>子元素。
解析过程中像<meta>、<qualifier>等子元素都很少使用，而下面就直接解析最常用的子元素<property>子元素。
BeanDefinitionParserDelegate.java
public void parsePropertyElements(Element beanEle, BeanDefinition bd) {
// 遍历<bean>所有的子元素
NodeList nl = beanEle.getChildNodes();
for (int i = 0; i < nl.getLength(); i++) {
Node node = nl.item(i);
if (isCandidateElement(node) && nodeNameEquals(node, PROPERTY_ELEMENT)) {
parsePropertyElement((Element) node, bd); // 如果是<property>元素, 则对其进行解析
}
}
}
public void parsePropertyElement(Element ele, BeanDefinition bd) {
String propertyName = ele.getAttribute(NAME_ATTRIBUTE); // <property>元素name属性
if (!StringUtils.hasLength(propertyName)) {
error("Tag 'property' must have a 'name' attribute", ele);
return;
}
this.parseState.push(new PropertyEntry(propertyName));
try {
// 如果同一个Bean中已经有相同名字的<property>存在, 直接返回
// 也就是说, 如果一个Bean中定义了两个名字一样的<property>元素, 只有第一个起作用.
if (bd.getPropertyValues().contains(propertyName)) {
error("Multiple 'property' definitions for property '" + propertyName + "'", ele);
return;
}
// 解析<property>元素, 返回的对象对应<property>元素的解析结果, 最终封装到PropertyValue中, 并设置到BeanDefinitionHolder中
Object val = parsePropertyValue(ele, bd, propertyName);
PropertyValue pv = new PropertyValue(propertyName, val);
parseMetaElements(ele, pv);
pv.setSource(extractSource(ele));
bd.getPropertyValues().addPropertyValue(pv);
}
finally {
this.parseState.pop();
}
}
public Object parsePropertyValue(Element ele, BeanDefinition bd, String propertyName) {
String elementName = (propertyName != null) ?
"<property> element for property '" + propertyName + "'" :
"<constructor-arg> element";
// 检查<property>的子元素, 只能是ref, value, list等(description, meta除外)其中的一个.
NodeList nl = ele.getChildNodes();
Element subElement = null;
for (int i = 0; i < nl.getLength(); i++) {
Node node = nl.item(i);
if (node instanceof Element && !nodeNameEquals(node, DESCRIPTION_ELEMENT) &&
!nodeNameEquals(node, META_ELEMENT)) {
if (subElement != null) {
error(elementName + " must not contain more than one sub-element", ele);
}
else {
subElement = (Element) node;
}
}
}
// 判断property元素是否含有ref和value属性, 不允许既有ref又有value属性.
// 同时也不允许ref和value属性其中一个与子元素共存.
boolean hasRefAttribute = ele.hasAttribute(REF_ATTRIBUTE);
boolean hasValueAttribute = ele.hasAttribute(VALUE_ATTRIBUTE);
if ((hasRefAttribute && hasValueAttribute) ||
((hasRefAttribute || hasValueAttribute) && subElement != null)) {
error(elementName +
" is only allowed to contain either 'ref' attribute OR 'value' attribute OR sub-element", ele);
}
// 如果属性是ref属性, 创建一个ref的数据对象RuntimeBeanReference, 封装了ref信息
if (hasRefAttribute) {
String refName = ele.getAttribute(REF_ATTRIBUTE);
if (!StringUtils.hasText(refName)) {
error(elementName + " contains empty 'ref' attribute", ele);
}
RuntimeBeanReference ref = new RuntimeBeanReference(refName);
ref.setSource(extractSource(ele));
return ref;
}
else if (hasValueAttribute) { // 如果属性是value属性, 创建一个数据对象TypedStringValue, 封装了value信息
TypedStringValue valueHolder = new TypedStringValue(ele.getAttribute(VALUE_ATTRIBUTE));
valueHolder.setSource(extractSource(ele));
return valueHolder;
}
else if (subElement != null) { // 如果当前<property>元素还有子元素
return parsePropertySubElement(subElement, bd);
}
else { // propery元素既没有ref或value属性, 也没有子元素, 解析出错返回null
error(elementName + " must specify a ref or value", ele);
return null;
}
}
property元素的子元素解析
BeanDefinitionParseDelegate.java
public Object parsePropertySubElement(Element ele, BeanDefinition bd) {
return parsePropertySubElement(ele, bd, null);
}
public Object parsePropertySubElement(Element ele, BeanDefinition bd, String defaultValueType) {
if (!isDefaultNamespace(ele)) { // 如果子元素没有使用Spring默认命名空间, 则使用用户自定义的规则解析
return parseNestedCustomElement(ele, bd);
}
else if (nodeNameEquals(ele, BEAN_ELEMENT)) { // 如果子元素是bean元素, 则使用解析<bean>元素的方法解析
BeanDefinitionHolder nestedBd = parseBeanDefinitionElement(ele, bd);
if (nestedBd != null) {
nestedBd = decorateBeanDefinitionIfRequired(ele, nestedBd, bd);
}
return nestedBd;
}
else if (nodeNameEquals(ele, REF_ELEMENT)) { // 如果子元素是ref, 有且只能有bean、local和parent 3个属性中的一个
String refName = ele.getAttribute(BEAN_REF_ATTRIBUTE); // 引用普通任意的bean
boolean toParent = false;
if (!StringUtils.hasLength(refName)) {
refName = ele.getAttribute(LOCAL_REF_ATTRIBUTE); // 引用同一个XML配置文件中的bean
if (!StringUtils.hasLength(refName)) {
refName = ele.getAttribute(PARENT_REF_ATTRIBUTE); // 引用父容器中的bean
toParent = true;
if (!StringUtils.hasLength(refName)) {
error("'bean', 'local' or 'parent' is required for <ref> element", ele);
return null;
}
}
}
// ref元素没有bean、local和parent 3个属性中的一个, 返回null.
if (!StringUtils.hasText(refName)) {
error("<ref> element contains empty target attribute", ele);
return null;
}
RuntimeBeanReference ref = new RuntimeBeanReference(refName, toParent);
ref.setSource(extractSource(ele));
return ref;
}
else if (nodeNameEquals(ele, IDREF_ELEMENT)) { // 如果子元素是<idref>, 使用解析idref元素的方法解析
return parseIdRefElement(ele);
}
else if (nodeNameEquals(ele, VALUE_ELEMENT)) { // 子元素是<value>
return parseValueElement(ele, defaultValueType);
}
else if (nodeNameEquals(ele, NULL_ELEMENT)) { // 子元素是<null>
TypedStringValue nullHolder = new TypedStringValue(null);
nullHolder.setSource(extractSource(ele));
return nullHolder;
}
else if (nodeNameEquals(ele, ARRAY_ELEMENT)) { // 子元素是<array>
return parseArrayElement(ele, bd);
}
else if (nodeNameEquals(ele, LIST_ELEMENT)) { // 子元素是<list>
return parseListElement(ele, bd);
}
else if (nodeNameEquals(ele, SET_ELEMENT)) { // 子元素是<set>
return parseSetElement(ele, bd);
}
else if (nodeNameEquals(ele, MAP_ELEMENT)) { // 子元素是<map>
return parseMapElement(ele, bd);
}
else if (nodeNameEquals(ele, PROPS_ELEMENT)) { // 子元素是<props>
return parsePropsElement(ele);
}
else { // 以上都不是, 说明配置错误, 返回null.
error("Unknown property sub-element: [" + ele.getNodeName() + "]", ele);
return null;
}
}
我们以 list 子元素进行分析
BeanDefinitionParseDelegate.java
public List<Object> parseListElement(Element collectionEle, BeanDefinition bd) {
// 获取<list>元素中的value-type属性, 即集合元素的数据类型
String defaultElementType = collectionEle.getAttribute(VALUE_TYPE_ATTRIBUTE);
NodeList nl = collectionEle.getChildNodes(); // <list>元素所有子节点
ManagedList<Object> target = new ManagedList<Object>(nl.getLength());
target.setSource(extractSource(collectionEle));
target.setElementTypeName(defaultElementType);
target.setMergeEnabled(parseMergeAttribute(collectionEle));
parseCollectionElements(nl, target, bd, defaultElementType); // 具体解析List元素中的值
return target;
}
protected void parseCollectionElements(
NodeList elementNodes, Collection<Object> target, BeanDefinition bd, String defaultElementType) {
// 遍历集合所有子节点
for (int i = 0; i < elementNodes.getLength(); i++) {
Node node = elementNodes.item(i);
if (node instanceof Element && !nodeNameEquals(node, DESCRIPTION_ELEMENT)) {
// 如果子节点是Element且不是<description>节点, 则添加进ManagedList.
// 同时触发对下层子元素的解析, 递归调用.
target.add(parsePropertySubElement((Element) node, bd, defaultElementType));
}
}
}
:-: BeanDefinition的注册
BeanDefinition信息已经在Ioc容器内建立了自己的数据结构，但是这些数据还不能供Ioc容器使用，需要在Ioc容器中对这写BeanDefinition数据进行注册。不同的元素解析方式都不同，但是最后的注册方式是一样的，我们还是以上面提到的bean元素为例。
:-: 
BeanDefinitionReaderUtils.java
public static void registerBeanDefinition(
BeanDefinitionHolder definitionHolder, BeanDefinitionRegistry registry)
throws BeanDefinitionStoreException {
String beanName = definitionHolder.getBeanName();
// 向IoC容器注册BeanDefinition
registry.registerBeanDefinition(beanName, definitionHolder.getBeanDefinition());
// 如果解析的BeanDefinition有别名, 向容器为其注册别名.
String[] aliases = definitionHolder.getAliases();
if (aliases != null) {
for (String alias : aliases) {
registry.registerAlias(beanName, alias);
}
}
}
上面的registry.registerBeanDefinition(beanName, definitionHolder.getBeanDefinition())是调用的注册位置，而BeanDefinitionRegistry仅仅是一个接口，而真正实现它的却是最原本的DefaultListableBeanFactory.registerBeanDefinition方法，值得一提的是DefaultListableBeanFactory.registerBeanDefinition方法在最新的Spring 4.0中稳定性方面做了很大改善。
:-: 
DefaultListableBeanFactory.java
public void registerBeanDefinition(String beanName, BeanDefinition beanDefinition)
throws BeanDefinitionStoreException {
Assert.hasText(beanName, "Bean name must not be empty");
Assert.notNull(beanDefinition, "BeanDefinition must not be null");
// 对解析得到的BeanDefinition校验
if (beanDefinition instanceof AbstractBeanDefinition) {
try {
((AbstractBeanDefinition) beanDefinition).validate();
}
catch (BeanDefinitionValidationException ex) {
throw new BeanDefinitionStoreException(beanDefinition.getResourceDescription(), beanName,
"Validation of bean definition failed", ex);
}
}
BeanDefinition oldBeanDefinition;
oldBeanDefinition = this.beanDefinitionMap.get(beanName);
if (oldBeanDefinition != null) {
if (!isAllowBeanDefinitionOverriding()) {
throw new BeanDefinitionStoreException(beanDefinition.getResourceDescription(), beanName,
"Cannot register bean definition [" + beanDefinition + "] for bean '" + beanName +
"': There is already [" + oldBeanDefinition + "] bound.");
}
else if (oldBeanDefinition.getRole() < beanDefinition.getRole()) {
if (this.logger.isWarnEnabled()) {
this.logger.warn("Overriding user-defined bean definition for bean '" + beanName +
"' with a framework-generated bean definition: replacing [" +
oldBeanDefinition + "] with [" + beanDefinition + "]");
}
}
else if (!beanDefinition.equals(oldBeanDefinition)) {
if (this.logger.isInfoEnabled()) {
this.logger.info("Overriding bean definition for bean '" + beanName +
"' with a different definition: replacing [" + oldBeanDefinition +
"] with [" + beanDefinition + "]");
}
}
else {
if (this.logger.isDebugEnabled()) {
this.logger.debug("Overriding bean definition for bean '" + beanName +
"' with an equivalent definition: replacing [" + oldBeanDefinition +
"] with [" + beanDefinition + "]");
}
}
this.beanDefinitionMap.put(beanName, beanDefinition);
}
else {
if (hasBeanCreationStarted()) {
// 注册的过程中需要线程同步, 以保证数据的一致性
synchronized (this.beanDefinitionMap) {
this.beanDefinitionMap.put(beanName, beanDefinition);
List<String> updatedDefinitions = new ArrayList<String>(this.beanDefinitionNames.size() + 1);
updatedDefinitions.addAll(this.beanDefinitionNames);
updatedDefinitions.add(beanName);
this.beanDefinitionNames = updatedDefinitions;
if (this.manualSingletonNames.contains(beanName)) {
Set<String> updatedSingletons = new LinkedHashSet<String>(this.manualSingletonNames);
updatedSingletons.remove(beanName);
this.manualSingletonNames = updatedSingletons;
}
}
}
else {
// 没有同名BeanDefinition注册过, 将Bean名字存入beanDefinitionNames
this.beanDefinitionMap.put(beanName, beanDefinition);
this.beanDefinitionNames.add(beanName);
this.manualSingletonNames.remove(beanName);
}
this.frozenBeanDefinitionNames = null;
}
if (oldBeanDefinition != null || containsSingleton(beanName)) {
resetBeanDefinition(beanName);
}
}
至此，注册完毕后，容器就可用了。虽然这是最原始的容器。
内容来源于网络，如有侵权，请联系作者删除！
相关文章
热门标签
更多最新文章
更多- 浏览(1327) 发布于 2023-01-15
- 浏览(1020) 发布于 2023-01-15
- 浏览(609) 发布于 2022-10-25
- 浏览(1092) 发布于 2022-10-25
- 浏览(832) 发布于 2022-10-25
目录
- BeanFactory实现Ioc
- BeanFactory源码
- BeanFactory的实现类XmlBeanFactory
- DefaultListableBeanFactory的源码
- 下面是XmlBeanFactory在使用过程中涉及到的类的关系图：
- BeanDefinition的加载、解析、注册过程分析：XmlBeanDefinitionReader
- XmlBeanDefinitionReader.java
- Spring的默认配置文件applicationContext.xml
- XmlBeanDefinitionReader.java
- XmlValidationModeDetecor.java
- XmlBeanDefinitionReader.java
- DefaultDocumentLoader.java
- XmlBeanDefinitionReader.java
- DefaultBeanDefinitionDocumentReader.java
- DefaultBeanDefinitionDocumentReader.java
- BeanDefinotionParseDelegate.java
- BeanDefinitionParserDelegate.java
- BeanDefinitionParseDelegate.java
- BeanDefinitionParseDelegate.java
- BeanDefinitionReaderUtils.java
- DefaultListableBeanFactory.java