《Jaxb2 转换XML文档》学习笔记

——完成Java对象和XML相互转换

前面有介绍过json-lib这个框架，在线博文：
http://www.cnblogs.com/hoojo/archive/2011/04/21/2023805.html

以及Jackson这个框架，在线博文：http://www.cnblogs.com/hoojo/archive/2011/04/22/2024628.html

它们都可以完成Java对象到XML的转换，但是还不是那么的完善。

还有XStream对JSON及XML的支持，它可以对JSON或XML的完美转换。在线博文：

http://www.cnblogs.com/hoojo/archive/2011/04/22/2025197.html

以及介绍Castor来完成Java对象到xml的相互转换。在线博文：http://www.cnblogs.com/hoojo/archive/2011/04/25/2026819.html

这次介绍Jaxb2完成xml的转换，Jaxb2使用了JDK的新特性。如：Annotation、GenericType等，Jaxb2需要在即将转换的JavaBean中添加annotation注解。下面我们就来看看Jaxb2是怎么样完成Java对象到XML之间的相互转换吧。

原文地址
Jaxb2 转换XML文档
http://www.cnblogs.com/hoojo/archive/2011/04/26/2029011.html

以下是学习笔记：
1，改造成Maven工程后的pom.xml文件

<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 http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.coderdream</groupId>
    <artifactId>jaxb2-demo</artifactId>
    <packaging>war</packaging>
    <version>0.0.1-SNAPSHOT</version>
    <name>jaxb2-demo Maven Webapp</name>
    <url>http://maven.apache.org</url>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <junit.version>4.11</junit.version>
    </properties>

    <dependencies>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>${junit.version}</version>
        </dependency>

        <dependency>
            <groupId>com.thoughtworks.xstream</groupId>
            <artifactId>xstream</artifactId>
            <version>1.4.7</version>
        </dependency>

    </dependencies>
    <build>
        <finalName>jaxb2-demo</finalName>
    </build>
</project>

2，完整的Jaxb2Test.java文件：

package com.hoo.test;

import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

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

import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import com.hoo.entity.Account;
import com.hoo.entity.AccountBean;
import com.hoo.entity.Birthday;
import com.hoo.entity.ListBean;
import com.hoo.entity.MapBean;

/**
 * function:Jaxb2 完成Java和XML的编组、解组
 * 
 * @author hoojo
 * @createDate 2011-4-25 上午11:54:06
 * @file Jaxb2Test.java
 * @package com.hoo.test
 * @project WebHttpUtils
 * @blog http://blog.csdn.net/IBM_hoojo
 * @email [e-mail]
 * @version 1.0
 */
public class Jaxb2Test {
    private JAXBContext context = null;

    private StringWriter writer = null;
    private StringReader reader = null;

    private AccountBean bean = null;

    @Before
    public void init() {
        bean = new AccountBean();
        bean.setAddress("北京");
        bean.setEmail("email");
        bean.setId(1);
        bean.setName("jack");
        Birthday day = new Birthday();
        day.setBirthday("2010-11-22");
        bean.setBirthday(day);

        try {
            context = JAXBContext.newInstance(AccountBean.class);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    @After
    public void destory() {
        context = null;
        bean = null;
        try {
            if (writer != null) {
                writer.flush();
                writer.close();
            }
            if (reader != null) {
                reader.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        System.gc();
    }

    public void fail(Object o) {
        System.out.println(o);
    }

    public void failRed(Object o) {
        System.err.println(o);
    }

    @Test
    public void testBean2XML() {
        try {
            failRed("---------testBean2XML---------");
            // 下面代码演示将对象转变为xml
            Marshaller mar = context.createMarshaller();
            writer = new StringWriter();
            mar.marshal(bean, writer);
            fail(writer);

            // 下面代码演示将上面生成的xml转换为对象
            reader = new StringReader(writer.toString());
            Unmarshaller unmar = context.createUnmarshaller();
            bean = (AccountBean) unmar.unmarshal(reader);
            fail(bean);
        } catch (JAXBException e) {
            e.printStackTrace();
        }
    }

    @Test
    public void testList2XML() {
        failRed("---------testList2XML---------");
        ListBean listBean = new ListBean();
        listBean.setName("list to xml");
        List<Object> list = new ArrayList<Object>();
        list.add(bean);
        bean = new AccountBean();
        bean.setAddress("china");
        bean.setEmail("[e-mail]");
        bean.setId(2);
        bean.setName("tom");
        Birthday day = new Birthday("2010-11-22");
        bean.setBirthday(day);

        Account acc = new Account();
        acc.setAddress("china");
        acc.setEmail("[e-mail]");
        acc.setId(2);
        acc.setName("tom");
        day = new Birthday("2010-11-22");
        acc.setBirthday(day);
        list.add(bean);
        list.add(acc);
        listBean.setList(list);

        try {
            context = JAXBContext.newInstance(ListBean.class);
            // 下面代码演示将对象转变为xml
            Marshaller mar = context.createMarshaller();
            writer = new StringWriter();
            mar.marshal(listBean, writer);
            fail(writer);

            // 下面代码演示将上面生成的xml转换为对象
            reader = new StringReader(writer.toString());
            Unmarshaller unmar = context.createUnmarshaller();
            listBean = (ListBean) unmar.unmarshal(reader);
            fail(listBean.getList().get(0));
            fail(listBean.getList().get(1));
            fail(listBean.getList().get(2));
        } catch (JAXBException e) {
            e.printStackTrace();
        }
    }

    /**
     * <b>function:</b>Map需要自己实现，可以构造一个简单的Map对象实现
     * http://metro.1045641.n5.nabble.com/Does-JAXB-2-0-support-Map-td1058084.html
     * 
     * @author hoojo
     * @createDate 2010-12-1 上午10:23:26
     */
    @Test
    public void testMap2XML() {
        failRed("---------testMap2XML---------");
        MapBean mapBean = new MapBean();
        HashMap<String, AccountBean> map = new HashMap<String, AccountBean>();
        map.put("NO1", bean);
        bean = new AccountBean();
        bean.setAddress("china");
        bean.setEmail("[e-mail]");
        bean.setId(2);
        bean.setName("tom");
        Birthday day = new Birthday("2010-11-22");
        bean.setBirthday(day);
        map.put("NO2", bean);
        mapBean.setMap(map);

        try {
            context = JAXBContext.newInstance(MapBean.class);
            // 下面代码演示将对象转变为xml
            Marshaller mar = context.createMarshaller();
            writer = new StringWriter();
            mar.marshal(mapBean, writer);
            fail(writer);

            // 下面代码演示将上面生成的xml转换为对象
            reader = new StringReader(writer.toString());
            Unmarshaller unmar = context.createUnmarshaller();
            mapBean = (MapBean) unmar.unmarshal(reader);
            fail(mapBean.getMap());
        } catch (JAXBException e) {
            e.printStackTrace();
        }
    }
}

3，运行结果：

---------testMap2XML---------
<?xml version="1.0" encoding="UTF-8" standalone="yes"?><mapBean><map><item><key>NO2</key><value number="2"><address>china</address><birthday><birthday>2010-11-22</birthday></birthday><email>[e-mail]</email><name>tom</name></value></item><item><key>NO1</key><value number="1"><address>北京</address><birthday><birthday>2010-11-22</birthday></birthday><email>email</email><name>jack</name></value></item></map></mapBean>
{NO2=tom#2#china#2010-11-22#[e-mail], NO1=jack#1#北京#2010-11-22#email}
---------testBean2XML---------
<?xml version="1.0" encoding="UTF-8" standalone="yes"?><account number="1"><address>北京</address><birthday><birthday>2010-11-22</birthday></birthday><email>email</email><name>jack</name></account>
jack#1#北京#2010-11-22#email
---------testList2XML---------
<?xml version="1.0" encoding="UTF-8" standalone="yes"?><list-bean name="list to xml"><bean number="1"><address>北京</address><birthday><birthday>2010-11-22</birthday></birthday><email>email</email><name>jack</name></bean><bean number="2"><address>china</address><birthday><birthday>2010-11-22</birthday></birthday><email>[e-mail]</email><name>tom</name></bean><account><address>china</address><birthday><birthday>2010-11-22</birthday></birthday><email>[e-mail]</email><id>2</id><name>tom</name></account></list-bean>
jack#1#北京#2010-11-22#email
tom#2#china#2010-11-22#[e-mail]
2#tom#[e-mail]#china#2010-11-22

4，git源代码地址：
https://git.oschina.net/coderdream/jaxb2-demo

5，源代码下载：