XML 和 java对象相互转换

xml和Java对象的转换不需要任何的第三方包，JDK自带这个转换API，方便简洁。

下面使用的是JDK自带的类，没有引用任何第三方jar包。

Unmarshaller 类使客户端应用程序能够将 XML 数据转换为 Java 内容对象树。

备注：marshal(序列化、排列、整理)

Marshaller 类使客户端应用程序能够将 Java 内容树转换回 XML 数据。

实体类(这个是要被包含的实体类，不需要加注解)一:

package org.ywzn.po;

public class User {

	private String id;

	private String name;

	private String passwrod;

	public User() {
		super();
	}

	public User(String id,String name,String passwrod) {
		super();
		this.id = id;
		this.name = name;
		this.passwrod = passwrod;
	}

	public String getId() {
		return id;
	}

	public void setId(String id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getPasswrod() {
		return passwrod;
	}

	public void setPasswrod(String passwrod) {
		this.passwrod = passwrod;
	}

	@Override
	public String toString() {
		return "User [id=" + id + ",name=" + name + ",passwrod=" + passwrod
				+ "]";
	}

}

package org.ywzn.po;

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class Room {

	private String id;

	private String address;

	private User user;

	public Room() {
		super();
	}

	public Room(String id,String address,User user) {
		super();
		this.id = id;
		this.address = address;
		this.user = user;
	}

	public String getId() {
		return id;
	}

	public void setId(String id) {
		this.id = id;
	}

	public String getAddress() {
		return address;
	}

	public void setAddress(String address) {
		this.address = address;
	}

	public User getUser() {
		return user;
	}

	public void setUser(User user) {
		this.user = user;
	}

	@Override
	public String toString() {
		return "Room [id=" + id + ",address=" + address + ",user=" + user
				+ "]";
	}

}

注意：

1、需要转换的model对象一定要添加@XmlRootElement注解，其里面的其他对象则不需要

2、需要转换的model对象一定要有不带参数的构造方法，包括该对象里面引用的对象。

package org.ywzn.main;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;

import org.ywzn.po.Room;
import org.ywzn.po.User;

public class App {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		User user = new User("1","夏小雪","111");
		Room room = new Room("1","桂林",user);
		try {
			JAXBContext context = JAXBContext.newInstance(Room.class);
			Marshaller createMarshaller = context.createMarshaller();
			createMarshaller.marshal(room,System.out);
		} catch (JAXBException e) {
			e.printStackTrace();
		}
	}

}

<?xml version="1.0" encoding="UTF-8" standalone="yes"?><room><address>桂林</address><id>1</id><user><id>1</id><name>夏小雪</name><passwrod>111</passwrod></user></room>

package org.ywzn.main;

import java.io.StringReader;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;

import org.ywzn.po.Room;

public class App2 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		String xmlStr = "<?xml version="1.0" encoding="UTF-8" standalone="yes"?><room><address>厦门</address><id>1</id><user><id>1</id><name>易中天</name><passwrod>111</passwrod></user></room>";  
        try {  
            JAXBContext context = JAXBContext.newInstance(Room.class);  
            Unmarshaller unmarshaller = context.createUnmarshaller();  
            Room room = (Room)unmarshaller.unmarshal(new StringReader(xmlStr));  
            System.out.println(room);
        } catch (JAXBException e) {  
            e.printStackTrace();  
        }  
	}

}

Room [id=1,address=厦门,user=User [id=1,name=易中天,passwrod=111]]

测试编码与是否省略xml头:

package org.ywzn.main;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;

import org.ywzn.po.Room;
import org.ywzn.po.User;

public class Java2XMLSetEncode {

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		User user = new User("1",user);
		try {
			JAXBContext context = JAXBContext.newInstance(Room.class);
			Marshaller createMarshaller = context.createMarshaller();
			createMarshaller.setProperty(Marshaller.JAXB_ENCODING,"UTF-8");// 编码格式
			createMarshaller
					.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT,true);// 是否格式化生成的xml串
			createMarshaller.setProperty(Marshaller.JAXB_FRAGMENT,false);// 是否省略xml头信息（<?xml

			createMarshaller.marshal(room,System.out);
			
			
		} catch (JAXBException e) {
			e.printStackTrace();
		}
	}

}

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<room>
    <address>桂林</address>
    <id>1</id>
    <user>
        <id>1</id>
        <name>夏小雪</name>
        <passwrod>111</passwrod>
    </user>
</room>

JAXB（Java Architecture for XML Binding) 是一个业界的标准，是一项可以根据XML Schema产生Java类的技术。该过程中，JAXB也提供了将XML实例文档反向生成Java对象树的方法，并能将Java对象树的内容重新写到XML实例文档。从另一方面来讲，JAXB提供了快速而简便的方法将XML模式绑定到Java表示，从而使得Java开发者在Java应用程序中能方便地结合XML数据和处理函数。

JAXBContext 类提供到 JAXB API 的客户端入口点。它提供了管理实现 JAXB 绑定框架操作所需的 XML/Java 绑定信息的抽象，这些操作包括：解组、编组和验证。

Demo的下载地址->这里

http://download.csdn.net/detail/u014175572/8721559

（编辑：李大同）

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