1.pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.5</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.yl</groupId>
    <artifactId>webcompontent</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>webcompontent</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

2.整合servlet

2.1 自定义一个servlet

package com.yl.webcompontent.servlet;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/** * 注册servlet */
@WebServlet(urlPatterns = "/hello")
public class MyServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req,resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("web servlet...");
    }
}

2.2 在启动类上扫描servlet，listener和filter所在的包

package com.yl.webcompontent;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;

@SpringBootApplication
@ServletComponentScan({"com.yl.webcompontent.filter","com.yl.webcompontent.servlet","com.yl.webcompontent.listener"})
public class WebcompontentApplication {

    public static void main(String[] args) {
        SpringApplication.run(WebcompontentApplication.class, args);
    }

}

3.整合listener

3.1 自定义监听器

package com.yl.webcompontent.listener;

import org.springframework.web.context.request.RequestContextListener;

import javax.servlet.ServletRequestEvent;
import javax.servlet.annotation.WebListener;

/** * 自定义监听器 */
@WebListener
public class MyListener extends RequestContextListener {
    @Override
    public void requestInitialized(ServletRequestEvent requestEvent) {
        System.out.println("listener init...");
    }

    @Override
    public void requestDestroyed(ServletRequestEvent requestEvent) {
        System.out.println("listener destroy...");
    }
}

3.1 扫描listener

package com.yl.webcompontent;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;

@SpringBootApplication
@ServletComponentScan({"com.yl.webcompontent.filter","com.yl.webcompontent.servlet","com.yl.webcompontent.listener"})
public class WebcompontentApplication {

    public static void main(String[] args) {
        SpringApplication.run(WebcompontentApplication.class, args);
    }

}

3.整合filter

3.1 方式一：使用@WebFilter注解，缺点：不可以设置优先级

3.1.1 自定义filter

package com.yl.webcompontent.filter;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;

/** * 自定义拦截器 */
@WebFilter(urlPatterns = "/*")
public class MyFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println("filter init...");
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        System.out.println("do my filter....");
        chain.doFilter(request,response);
    }

    @Override
    public void destroy() {
        System.out.println("filter destroy...");
    }
}

3.1.2 扫描filter

package com.yl.webcompontent;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;

@SpringBootApplication
@ServletComponentScan({"com.yl.webcompontent.filter","com.yl.webcompontent.servlet","com.yl.webcompontent.listener"})
public class WebcompontentApplication {

    public static void main(String[] args) {
        SpringApplication.run(WebcompontentApplication.class, args);
    }

}

3.2 方式二：使用@Component注解，缺点：不可以设置拦截路径

package com.yl.filter.filter;

import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

import javax.servlet.*;
import java.io.IOException;

@Component
@Order(99)
public class MyFilter03 implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        System.out.println("do myFilter03...");
        chain.doFilter(request,response);
    }

    @Override
    public void destroy() {

    }
}

3.3 方式三：提供一个FilterRegistrationBean的实例（推荐使用这种方式，路径优先级等都可以在实例里设置）

3.3.1 自定义filter

package com.yl.filter.filter;

import javax.servlet.*;
import java.io.IOException;

public class MyFilter05 implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException, ServletException {
        System.out.println("do myFilter05...");
        filterChain.doFilter(request,response);
    }

    @Override
    public void destroy() {

    }
}

3.3.2 注册filter

package com.yl.filter.filter;

import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.util.Arrays;

@Configuration
public class FilterConfiguration {

    @Bean
    FilterRegistrationBean<MyFilter04> filter04FilterRegistrationBean() {
        FilterRegistrationBean<MyFilter04> bean = new FilterRegistrationBean<>();
        //设置优先级
        bean.setOrder(90);
        //指定过滤器
        bean.setFilter(new MyFilter04());
        //设置拦截路径
        bean.setUrlPatterns(Arrays.asList("/*"));
        return bean;
    }

    @Bean
    FilterRegistrationBean<MyFilter05> filter05FilterRegistrationBean() {
        FilterRegistrationBean<MyFilter05> bean = new FilterRegistrationBean<>();
        //设置优先级
        bean.setOrder(89);
        //指定过滤器
        bean.setFilter(new MyFilter05());
        //设置拦截路径
        bean.setUrlPatterns(Arrays.asList("/*"));
        return bean;
    }
}