在这篇文章中，我们将学习如何使用DOM XML Parser在Java中创建一个XML文件。DOM提供了许多方便的类来轻松创建一个XML文件。首先，你必须用DocumentBuilder类创建一个Document，用Element类定义所有的XML内容-节点，属性。最后，使用Transformer类将整个XML内容输出到流输出，通常是一个文件。

开发过程步骤

1. users.xml输出文件
2. Java DOM解析器在Java中创建一个XML文件

1. users.xml输出文件

在这个例子的最后，将创建以下名为 "users.xml "的XML文件。

<?xmlversion="1.0"encoding="UTF-8"standalone="no"?>
<Users>
    <User id="1">
        <firstName>Ramesh</firstName>
        <lastName>Fadatare</lastName>
        <age>28</age>
        <gender>Male</gender>
    </User>
    <User id="2">
        <firstName>John</firstName>
        <lastName>Cena</lastName>
        <age>45</age>
        <gender>Male</gender>
    </User>
    <User id="3">
        <firstName>Tom</firstName>
        <lastName>Cruise</lastName>
        <age>40</age>
        <gender>Male</gender>
    </User>
</Users>

2. 用Java DOM解析器来创建一个XML文件

让我们使用DOM解析器创建一个程序来在Java中创建一个XML文件。

package net.javaguides.javaxmlparser.dom;

import java.io.File;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;

public class CreateXMLFileInJava {
    public static void main(String[] args) {
        DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
        DocumentBuilder dBuilder;
        try {
            dBuilder = dbFactory.newDocumentBuilder();
            Document doc = dBuilder.newDocument();
            // add elements to Document
            Element rootElement = doc.createElement("Users");
            // append root element to document
            doc.appendChild(rootElement);

            // append first child element to root element
            rootElement.appendChild(createUserElement(doc, "1", "Ramesh", "Fadatare", "28", "Male"));

            // append second child
            rootElement.appendChild(createUserElement(doc, "2", "John", "Cena", "45", "Male"));

            // append third child
            rootElement.appendChild(createUserElement(doc, "3", "Tom", "Cruise", "40", "Male"));

            // for output to file, console
            TransformerFactory transformerFactory = TransformerFactory.newInstance();
            Transformer transformer = transformerFactory.newTransformer();
            // for pretty print
            transformer.setOutputProperty(OutputKeys.INDENT, "yes");
            DOMSource source = new DOMSource(doc);

            // write to console or file
            StreamResult console = new StreamResult(System.out);
            StreamResult file = new StreamResult(new File("create_users.xml"));

            // write data
            transformer.transform(source, console);
            transformer.transform(source, file);

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private static Node createUserElement(Document doc, String id, String firstName, String lastName, String age,
        String gender) {
        Element user = doc.createElement("User");

        // set id attribute
        user.setAttribute("id", id);

        // create firstName element
        user.appendChild(createUserElements(doc, user, "firstName", firstName));

        // create lastName element
        user.appendChild(createUserElements(doc, user, "lastName", lastName));

        // create age element
        user.appendChild(createUserElements(doc, user, "age", age));

        // create gender element
        user.appendChild(createUserElements(doc, user, "gender", gender));

        return user;
    }

    // utility method to create text node
    private static Node createUserElements(Document doc, Element element, String name, String value) {
        Element node = doc.createElement(name);
        node.appendChild(doc.createTextNode(value));
        return node;
    }
}

上述程序的一个输出：

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<Users>
<User id="1">
<firstName>Ramesh</firstName>
<lastName>Fadatare</lastName>
<age>28</age>
<gender>Male</gender>
</User>
<User id="2">
<firstName>John</firstName>
<lastName>Cena</lastName>
<age>45</age>
<gender>Male</gender>
</User>
<User id="3">
<firstName>Tom</firstName>
<lastName>Cruise</lastName>
<age>40</age>
<gender>Male</gender>
</User>
</Users>

注意，为了调试，你可以改变StreamResult来输出XML内容到你的控制台。
写到控制台或文件：

StreamResult console = new StreamResult(System.out);
StreamResult file = new StreamResult(new File("create_users.xml"));
transformer.transform(source, console); // to console
transformer.transform(source, file); // to file