《xStream完美转换XML、JSON》学习笔记

xStream框架

xStream可以轻易的将Java对象和xml文档相互转换，而且可以修改某个特定的属性和节点名称，而且也支持json的转换；

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

它们都完美支持JSON，但是对xml的支持还不是很好。一定程度上限制了对Java对象的描述，不能让xml完全体现到对Java对象的描述。这里将会介绍xStream对JSON、XML的完美支持。xStream不仅对XML的转换非常友好，而且提供annotation注解，可以在JavaBean中完成对xml节点、属性的描述。以及对JSON也支持，只需要提供相关的JSONDriver就可以完成转换。


原文地址
xStream完美转换XML、JSON
http://www.cnblogs.com/hoojo/archive/2011/04/22/2025197.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>xsteam-demo</artifactId>
    <packaging>war</packaging>
    <version>0.0.1-SNAPSHOT</version>
    <name>xsteam-demo Maven Webapp</name>
    <url>http://maven.apache.org</url>
    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.8.2</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>com.thoughtworks.xstream</groupId>
            <artifactId>xstream</artifactId>
            <version>1.4.8</version>
        </dependency>

        <dependency>
            <groupId>org.codehaus.jettison</groupId>
            <artifactId>jettison</artifactId>
            <version>1.3.7</version>
        </dependency>

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

2，完整的XStreamTest.java文件：

package com.hoo.test;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.StringReader;
import java.io.Writer;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.codehaus.jettison.json.JSONException;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import com.hoo.entity.Birthday;
import com.hoo.entity.Classes;
import com.hoo.entity.Student;
import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.io.HierarchicalStreamWriter;
import com.thoughtworks.xstream.io.json.JettisonMappedXmlDriver;
import com.thoughtworks.xstream.io.json.JsonHierarchicalStreamDriver;
import com.thoughtworks.xstream.io.json.JsonWriter;

/**
 * <b>function:</b>Java对象和XML字符串的相互转换 jar-lib-version: xstream-1.3.1
 * 
 * @author hoojo
 * @createDate Nov 27, 2010 12:15:15 PM
 * @file XStreamTest.java
 * @package com.hoo.test
 * @project WebHttpUtils
 * @blog http://blog.csdn.net/IBM_hoojo
 * @email [e-mail]
 * @version 1.0
 */
public class XStreamTest {

    private XStream xstream = null;
    private ObjectOutputStream out = null;
    private ObjectInputStream in = null;

    private Student bean = null;

    /**
     * <b>function:</b>初始化资源准备
     * 
     * @author hoojo
     * @createDate Nov 27, 2010 12:16:28 PM
     */
    @Before
    public void init() {
        try {
            xstream = new XStream();
            // xstream = new XStream(new DomDriver()); // 需要xpp3 jar
        } catch (Exception e) {
            e.printStackTrace();
        }
        bean = new Student();
        bean.setAddress("china");
        bean.setEmail("[e-mail]");
        bean.setId(1);
        bean.setName("jack");
        Birthday day = new Birthday();
        day.setBirthday("2010-11-22");
        bean.setBirthday(day);
    }

    /**
     * <b>function:</b>释放对象资源
     * 
     * @author hoojo
     * @createDate Nov 27, 2010 12:16:38 PM
     */
    @After
    public void destory() {
        xstream = null;
        bean = null;
        try {
            if (out != null) {
                out.flush();
                out.close();
            }
            if (in != null) {
                in.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        System.gc();
    }

    public final void fail(String string) {
        System.out.println(string);
    }

    public final void failRed(String string) {
        System.err.println(string);
    }

    @Test
    public void writeList2XML4Annotation() {
        try {
            failRed("---------annotation Bean --> XML---------");
            Student stu = new Student();
            stu.setName("jack");
            Classes c = new Classes("一班", bean, stu);
            c.setNumber(2);
            // 对指定的类使用Annotation
            // xstream.processAnnotations(Classes.class);
            // 启用Annotation
            // xstream.autodetectAnnotations(true);
            xstream.alias("student", Student.class);
            fail(xstream.toXML(c));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    @Test
    public void writeList2XML4Annotation2() {
        try {
            failRed("---------annotation Bean --> XML---------");
            Student stu = new Student();
            stu.setName("jack");
            Classes c = new Classes("一班", bean, stu);
            c.setNumber(2);
            // 对指定的类使用Annotation
            xstream.processAnnotations(Classes.class);
            // 启用Annotation
            xstream.autodetectAnnotations(true);
            xstream.alias("student", Student.class);
            fail(xstream.toXML(c));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * <b>function:</b>Java Map集合转XML
     * 
     * @author hoojo
     * @createDate Nov 27, 2010 1:13:26 PM
     */
    @Test
    public void writeMap2XML() {
        try {
            failRed("---------Map --> XML---------");
            Map<String, Student> map = new HashMap<String, Student>();
            map.put("No.1", bean);// put

            bean = new Student();
            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("No.2", bean);// put

            bean = new Student();
            bean.setName("jack");
            map.put("No.3", bean);// put

            xstream.alias("student", Student.class);
            xstream.alias("key", String.class);
            xstream.useAttributeFor(Student.class, "id");
            xstream.useAttributeFor("birthday", String.class);
            fail(xstream.toXML(map));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * <b>function:</b>用OutStream输出流写XML
     * 
     * @author hoojo
     * @createDate Nov 27, 2010 1:13:48 PM
     */
    @Test
    public void writeXML4OutStream() {
        try {
            out = xstream.createObjectOutputStream(System.out);
            Student stu = new Student();
            stu.setName("jack");
            Classes c = new Classes("一班", bean, stu);
            c.setNumber(2);
            failRed("---------ObjectOutputStream # JavaObject--> XML---------");
            out.writeObject(stu);
            out.writeObject(new Birthday("2010-05-33"));
            out.write(22);// byte
            out.writeBoolean(true);
            out.writeFloat(22.f);
            out.writeUTF("hello");

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

    /**
     * <b>function:</b>用InputStream将XML文档转换成java对象 需要额外的jar xpp3-main.jar
     * 
     * @author hoojo
     * @createDate Nov 27, 2010 1:14:52 PM
     */
    @Test
    public void readXML4InputStream() {
        try {
            String s = "<object-stream><com.hoo.entity.Student><id>0</id><name>jack</name>"
                    + "</com.hoo.entity.Student><com.hoo.entity.Birthday><birthday>2010-05-33</birthday>"
                    + "</com.hoo.entity.Birthday><byte>22</byte><boolean>true</boolean><float>22.0</float>"
                    + "<string>hello</string></object-stream>";
            failRed("---------ObjectInputStream## XML --> javaObject---------");
            StringReader reader = new StringReader(s);
            in = xstream.createObjectInputStream(reader);
            Student stu = (Student) in.readObject();
            Birthday b = (Birthday) in.readObject();
            byte i = in.readByte();
            boolean bo = in.readBoolean();
            float f = in.readFloat();
            String str = in.readUTF();
            System.out.println(stu);
            System.out.println(b);
            System.out.println(i);
            System.out.println(bo);
            System.out.println(f);
            System.out.println(str);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * <b>function:</b>将XML字符串转换成Java对象
     * 
     * @author hoojo
     * @createDate Nov 27, 2010 2:39:06 PM
     */
    @SuppressWarnings("unchecked")
    @Test
    public void readXml2Object() {
        try {
            failRed("-----------Xml >>> Bean--------------");
            Student stu = (Student) xstream.fromXML(xstream.toXML(bean));
            fail(stu.toString());

            List<Student> list = new ArrayList<Student>();
            list.add(bean);// add

            Map<String, Student> map = new HashMap<String, Student>();
            map.put("No.1", bean);// put

            bean = new Student();
            bean.setAddress("china");
            bean.setEmail("[e-mail]");
            bean.setId(2);
            bean.setName("tom");
            Birthday day = new Birthday("2010-11-22");
            bean.setBirthday(day);
            list.add(bean);// add
            map.put("No.2", bean);// put

            bean = new Student();
            bean.setName("jack");
            list.add(bean);// add
            map.put("No.3", bean);// put

            failRed("==========XML >>> List===========");
            List<Student> studetns = (List<Student>) xstream.fromXML(xstream.toXML(list));
            fail("size:" + studetns.size());// 3
            for (Student s : studetns) {
                fail(s.toString());
            }

            failRed("==========XML >>> Map===========");
            Map<String, Student> maps = (Map<String, Student>) xstream.fromXML(xstream.toXML(map));
            fail("size:" + maps.size());// 3
            Set<String> key = maps.keySet();
            Iterator<String> iter = key.iterator();
            while (iter.hasNext()) {
                String k = iter.next();
                fail(k + ":" + map.get(k));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * <b>function:</b>XStream结合JettisonMappedXmlDriver驱动，转换Java对象到JSON 需要添加jettison jar
     * 
     * @author hoojo
     * @createDate Nov 27, 2010 1:23:18 PM
     */
    @Test
    public void writeEntity2JETTSON() {
        failRed("=======JettisonMappedXmlDriver===JavaObject >>>> JaonString=========");
        xstream = new XStream(new JettisonMappedXmlDriver());
        xstream.setMode(XStream.NO_REFERENCES);
        xstream.alias("student", Student.class);
        fail(xstream.toXML(bean));
    }

    /**
     * <b>function:</b>用XStream结合JsonHierarchicalStreamDriver驱动 转换java对象为JSON字符串
     * 
     * @author hoojo
     * @createDate Nov 27, 2010 1:16:46 PM
     */
    @Test
    public void writeEntiry2JSON() {
        failRed("======JsonHierarchicalStreamDriver====JavaObject >>>> JaonString=========");
        xstream = new XStream(new JsonHierarchicalStreamDriver());
        // xstream.setMode(XStream.NO_REFERENCES);
        xstream.alias("student", Student.class);
        failRed("-------Object >>>> JSON---------");
        fail(xstream.toXML(bean));

        // failRed("========JsonHierarchicalStreamDriver==删除根节点=========");
        // 删除根节点
        xstream = new XStream(new JsonHierarchicalStreamDriver() {
            public HierarchicalStreamWriter createWriter(Writer out) {
                return new JsonWriter(out, JsonWriter.DROP_ROOT_MODE);
            }
        });
        // xstream.setMode(XStream.NO_REFERENCES);
        xstream.alias("student", Student.class);
        fail(xstream.toXML(bean));
    }

    @Test
    public void writeList2JSON() {
        failRed("======JsonHierarchicalStreamDriver====JavaObject >>>> JaonString=========");
        JsonHierarchicalStreamDriver driver = new JsonHierarchicalStreamDriver();
        xstream = new XStream(driver);
        // xstream = new XStream(new JettisonMappedXmlDriver());//转换错误
        // xstream.setMode(XStream.NO_REFERENCES);
        xstream.alias("student", Student.class);

        List<Student> list = new ArrayList<Student>();
        list.add(bean);// add

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

        bean = new Student();
        bean.setName("jack");
        list.add(bean);// add

        fail(xstream.toXML(list));

        // failRed("========JsonHierarchicalStreamDriver==删除根节点=========");
        // 删除根节点
        xstream = new XStream(new JsonHierarchicalStreamDriver() {
            public HierarchicalStreamWriter createWriter(Writer out) {
                return new JsonWriter(out, JsonWriter.DROP_ROOT_MODE);
            }
        });
        xstream.alias("student", Student.class);
        fail(xstream.toXML(list));
    }

    @Test
    public void writeMap2JSON() {
        failRed("======JsonHierarchicalStreamDriver==== Map >>>> JaonString=========");
        xstream = new XStream(new JsonHierarchicalStreamDriver());
        // xstream = new XStream(new JettisonMappedXmlDriver());
        xstream.alias("student", Student.class);

        Map<String, Student> map = new HashMap<String, Student>();
        map.put("No.1", bean);// put

        bean = new Student();
        bean.setAddress("china");
        bean.setEmail("[e-mail]");
        bean.setId(2);
        bean.setName("tom");
        bean.setBirthday(new Birthday("2010-11-21"));
        map.put("No.2", bean);// put

        bean = new Student();
        bean.setName("jack");
        map.put("No.3", bean);// put

        fail(xstream.toXML(map));

        // failRed("========JsonHierarchicalStreamDriver==删除根节点=========");
        // 删除根节点
        xstream = new XStream(new JsonHierarchicalStreamDriver() {
            public HierarchicalStreamWriter createWriter(Writer out) {
                return new JsonWriter(out, JsonWriter.DROP_ROOT_MODE);
            }
        });
        xstream.alias("student", Student.class);
        fail(xstream.toXML(map));
    }

    /**
     * <b>function:</b>JsonHierarchicalStreamDriver可以将简单的json字符串转换成java对象，list、map转换不成功；
     * JsonHierarchicalStreamDriver读取JSON字符串到java对象出错
     * 
     * @author hoojo
     * @createDate Nov 27, 2010 1:22:26 PM
     * @throws JSONException
     */
    @Test
    public void readJSON2Object() throws JSONException {
        String json = "{\"student\": {" + "\"id\": 1," + "\"name\": \"haha\"," + "\"email\": \"email\","
                + "\"address\": \"address\"," + "\"birthday\": {" + "\"birthday\": \"2010-11-22\"" + "}" + "}}";
        // JsonHierarchicalStreamDriver读取JSON字符串到java对象出错，但JettisonMappedXmlDriver可以
        xstream = new XStream(new JettisonMappedXmlDriver());
        xstream.alias("student", Student.class);
        fail(xstream.fromXML(json).toString());

        // JettisonMappedXmlDriver转换List集合出错，但JsonHierarchicalStreamDriver可以转换正确
//        xstream = new XStream(new JsonHierarchicalStreamDriver());
//        xstream.alias("student", Student.class);
//        
//        // JettisonMappedXmlDriver 转换的字符串
//        // {"list":{"student":[{"id":1,"name":"haha","email":"email","address":"address","birthday":[{},"2010-11-22"]}]},"student":{"id":2,"name":"tom","email":"[e-mail]","address":"china","birthday":[{},"2010-11-22"]}}
//        json = "{\"list\": [{" + "\"id\": 1," + "\"name\": \"haha\"," + "\"email\": \"email\","
//                + "\"address\": \"address\"," + "\"birthday\": {" + "\"birthday\": \"2010-11-22\"" + "}" + "},{"
//                + "\"id\": 2," + "\"name\": \"tom\"," + "\"email\": \"[e-mail]\"," + "\"address\": \"china\","
//                + "\"birthday\": {" + "\"birthday\": \"2010-11-22\"" + "}" + "}]}";
//        System.out.println(json);// 用js转换成功
//        List list = (List) xstream.fromXML(json);
        //System.out.println(list.size());// 0好像转换失败
    }
}

3，运行结果：

---------annotation Bean --> XML---------
<class 名称="一班">
  <Students>
    <id>1</id>
    <name>jack</name>
    <email>[e-mail]</email>
    <address>china</address>
    <birthday>
      <birthday>2010-11-22</birthday>
    </birthday>
  </Students>
  <Students>
    <id>0</id>
    <name>jack</name>
  </Students>
  <created>1439030984003</created>
</class>
---------ObjectInputStream## XML --> javaObject---------
jack#0#null#null#null
2010-05-33
22
true
22.0
hello
---------ObjectOutputStream # JavaObject--> XML---------
<object-stream>
  <com.hoo.entity.Student>
    <id>0</id>
    <name>jack</name>
  </com.hoo.entity.Student>
  <com.hoo.entity.Birthday>
    <birthday>2010-05-33</birthday>
  </com.hoo.entity.Birthday>
  <byte>22</byte>
  <boolean>true</boolean>
  <float>22.0</float>
  <string>hello</string>
</object-stream>-----------Xml >>> Bean--------------
==========XML >>> List===========
==========XML >>> Map===========
=======JettisonMappedXmlDriver===JavaObject >>>> JaonString=========
---------annotation Bean --> XML---------
======JsonHierarchicalStreamDriver====JavaObject >>>> JaonString=========
-------Object >>>> JSON---------
======JsonHierarchicalStreamDriver====JavaObject >>>> JaonString=========
---------Map --> XML---------
======JsonHierarchicalStreamDriver==== Map >>>> JaonString=========

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

5，源代码下载：