xStream完美转换XMLJSON

Posted 2020-08-09

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。

一、准备工作

1、 下载jar包、及官方资源

xStream的jar下载地址：

http://download.csdn.net/detail/u013791374/9636008

官方的示例很全，官方参考示例：http://xstream.codehaus.org/tutorial.html

添加xstream-1.3.1.jar文件到工程中，就可以开始下面的工作；

2、 测试用例代码

import com.thoughtworks.xstream.XStream;

/**
 * @author zwj
 *
 * 2016-9-21下午3:09:53
 * XStream java转换xml
 */
public class XStreamTest {
    
    public static void main(String[] args) {
        System.out.println(setBean());
   
    }
    public static String setBean(){
        Student sdt = new Student();
        sdt.setId(1);
        sdt.setName("张无忌");
        sdt.setEmail("[email protected]");
        sdt.setAddress("www.baidu.com");
        return beanToXml(sdt);
    }
    
    public static String beanToXml(Student sdt){
        XStream xst = new XStream();
        xst.alias("xml", sdt.getClass());//设置别名
        return xst.toXML(sdt);//将对象转换成xml
    }
}

通过XStream对象的toXML方法就可以完成Java对象到XML的转换，toXML方法还有2个相同签名的方法，需要传递一个流。然后通过流来完成xml信息的输出。

3、 需要的JavaBean

package com.hoo.entity;

package com.cn.test.objecttoxml;

import org.apache.commons.lang.builder.ToStringBuilder;
import org.apache.commons.lang.builder.ToStringStyle;

public class Student {
    private int id;

    private String name;

    private String email;

    private String address;
    
    public String toString() {
        return ToStringBuilder.reflectionToString(this, ToStringStyle.SHORT_PREFIX_STYLE);
    }

    //getter、setter
  
}

运行后结果如下：

------------Bean->XML------------

<xml>
  <id>1</id>
  <name>张无忌</name>
  <email>[email protected]</email>
  <address>皖六安</address>
</xml>

2、 将List集合转换成xml文档

/**

 * <b>function:</b>将Java的List集合转换成XML对象

 * @author hoojo

 * @createDate Nov 27, 2010 12:20:07 PM

 */

    public static void main(String[] args) {        System.out.println(setBean());    }    public static String setBean(){        List<Student> list = new ArrayList<Student>();        Student sd = new Student();        sd.setId(1);        sd.setName("张无忌");        sd.setEmail("[email protected]");        sd.setAddress("皖六安");        list.add(sd);                Student sd2 = new Student();        sd2.setId(1);        sd2.setName("张无忌2");        sd2.setEmail("[email protected]");        sd2.setAddress("皖六安2");        list.add(sd2);        return beanToXml(list);    }        public static String beanToXml(Object obj){        XStream xst = new XStream();        //xstream list转xml 设置<list>标签别名  xstream.alias("xxx", List.class);        xst.alias("xml",List.class);        //aliasPackage 设置包别名        xst.aliasPackage("list", "com.cn.test.objecttoxml");        return xst.toXML(obj);    }

上面的代码运行后，结果如下：

----------List-->XML----------

<xml>
  <list.Student>
    <id>1</id>
    <name>张无忌</name>
    <email>[email protected]</email>
    <address>皖六安</address>
  </list.Student>
  <list.Student>
    <id>1</id>
    <name>张无忌2</name>
    <email>[email protected]</email>
    <address>皖六安2</address>
  </list.Student>
</xml>

如果不加xstream.addImplicitCollection(ListBean.class, "list");

这个设置的话，会出现一个List节点包裹着Student节点元素。添加addImplicitCollection可以忽略这个list节点元素。那么上面的list节点就不存在，只会在beans元素中出现name、student这2个xml元素标签；

setMode是设置相同的对象的引用方式，如果设置XStream.NO_REFERENCES就是不引用，会输出2分相同的Student元素。如果是XStream.ID_REFERENCES会引用相同的那个对象的id属性，如果是XStream.XPATH_ABSOLUTE_REFERENCES引用，那么它将显示xpath路径。上面采用的id引用，<student reference="3"/>这个引用了id=3的那个student标签元素；

useAttributeFor是设置某个节点显示到父节点的属性中，也就是将指定class中的指定属性，在这个class元素节点的属性中显示。

如：<student><name>hoojo</name></student>

设置好后就是这样的结果：<student name=”hoojo”></student>

aliasAttribute是修改属性名称。

3、 Map集合转换xml文档

/**

 * <b>function:</b>Java Map集合转XML

 * @author hoojo

 * @createDate Nov 27, 2010 1:13:26 PM

 */

@Test

public void writeMap2XML() {

    try {

Map<String,Student> map = new HashMap<String,Student>();
        Student sd = new Student();
        sd.setId(1);
        sd.setName("张无忌");
        sd.setEmail("[email protected]");
        sd.setAddress("皖六安");
        map.put("No.1", sd);
        
        Student sd2 = new Student();
        sd2.setId(2);
        sd2.setName("张无忌2");
        sd2.setEmail("[email protected]");
        sd2.setAddress("皖六安2");
        map.put("No.2", sd2);
        return beanToXml(map)

    } catch (Exception e) {

        e.printStackTrace();

    }

}

public static String beanToXml(Object obj){
        XStream xst = new XStream();
        //不需要设置MAP.CLASS
        //xst.alias("xml",Map.class);
        xst.alias("student", Student.class);
        xst.alias("key", String.class);
        xst.useAttributeFor(Student.class, "id");
        //aliasPackage 设置包别名
        return xst.toXML(obj);
    }

运行后结果如下：

---------Map --> XML---------

<map>
  <entry>
    <key>No.1</key>
    <student id="1">
      <name>张无忌</name>
      <email>[email protected]</email>
      <address>皖六安</address>
    </student>
  </entry>
  <entry>
    <key>No.2</key>
    <student id="2">
      <name>张无忌2</name>
      <email>zhangwuj[email protected]</email>
      <address>皖六安2</address>
    </student>
  </entry>
</map>

5、 用OutStream输出流写XML

/**

 * <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();

    }

}

使用输出流后，可以通过流对象完成xml的构建，即使没有JavaBean对象，你可以用流来构建一个复杂的xml文档，运行后结果如下：

---------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>

三、XML内容转换Java对象

1、 将xml文档转换成Java对象

/**

 * <b>function:</b>将XML字符串转换成Java对象

 * @author hoojo

 * @createDate Nov 27, 2010 2:39:06 PM

 */

@Test

public void readXml2Object() {

    try {
        Student sd = new Student();
        sd.setId(1);
        sd.setName("张无忌");
        sd.setEmail("[email protected]");
        sd.setAddress("皖六安");
        xst.alias("xml",obj.getClass());
        String xmlStr = xst.toXML(obj);
        System.out.println("java对象转xml："+xmlStr);

       Student sdt  = (Student)xst.fromXML(xmlStr);
       System.out.println("对象转换xml方法："+sdt.toString());

    } catch (Exception e) {

        e.printStackTrace();

    }

}

运行后结果如下：

-----------Xml >>> Bean--------------

java对象转xml：<xml>  <id>1</id>  <name>张无忌</name>  <email>[email protected]</email>  <address>皖六安</address></xml>对象转换xml方法：Student[id=1,name=张无忌,[email protected],address=皖六安]

怎么样，成功的完成XML到JavaBean、List、Map的转换，更多对象转换还需要大家一一尝试。用法类似~这里就不一样赘述。

四、XStream对JSON的支持

xStream对JSON也有非常好的支持，它提供了2个模型驱动。用这2个驱动可以完成Java对象到JSON的相互转换。使用JettisonMappedXmlDriver驱动，将Java对象转换成json，需要添加jettison.jar

1、 用JettisonMappedXmlDriver完成Java对象到JSON的转换

/**

 * <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));

}

运行后结果如下：

=======JettisonMappedXmlDriver===JavaObject >>>> JaonString=========

{"student":{"id":1,"name":"jack","email":"[email protected]","address":"china","birthday":[{},"2010-11-22"]}}

JSON的转换和XML的转换用法一样，只是创建XStream需要传递一个参数，这个参数就是xml到JSON映射转换的驱动。这里会降到两个驱动，分别是JettisonMappedXmlDriver、JsonHierarchicalStreamDriver。

2、 JsonHierarchicalStreamDriver完成Java对象到JSON的转换

/**

 * <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));

}

运行后结果如下：

======JsonHierarchicalStreamDriver====JavaObject >>>> JaonString=========

-------Object >>>> JSON---------

{"student": {

  "id": 1,

  "name": "jack",

  "email": "[email protected]",

  "address": "china",

  "birthday": {

    "birthday": "2010-11-22"

  }

}}

{

  "id": 1,

  "name": "jack",

  "email": "[email protected]",

  "address": "china",

  "birthday": {

    "birthday": "2010-11-22"

  }

}

使用JsonHierarchicalStreamDriver转换默认会给转换后的对象添加一个根节点，但是在构建JsonHierarchicalStreamDriver驱动的时候，你可以重写createWriter方法，删掉根节点。

看上面的结果，一个是默认带根节点的JSON对象，它只是将类名作为一个属性，将对象作为该属性的一个值。而另一个没有带根属性的JSON就是通过重写createWriter方法完成的。

3、 将List集合转换成JSON字符串

@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("[email protected]");

    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));

}

运行后结果如下

======JsonHierarchicalStreamDriver====JavaObject >>>> JaonString=========

##{"list": [

  {

    "id": 1,

    "name": "jack",

    "email": "[email protected]",

    "address": "china",

    "birthday": {

      "birthday": "2010-11-22"

    }

  },

  {

    "id": 2,

    "name": "tom",

    "email": "[email protected]",

    "address": "china",

    "birthday": {

      "birthday": "2010-11-22"

    }

  },

  {

    "id": 0,

    "name": "jack"

  }

]}

#[

  {

    "id": 1,

    "name": "jack",

    "email": "[email protected]",

    "address": "china",

    "birthday": {

      "birthday": "2010-11-22"

    }

  },

  {

    "id": 2,

    "name": "tom",

    "email": "[email protected]",

    "address": "china",

    "birthday": {

      "birthday": "2010-11-22"

    }

  },

  {

    "id": 0,

    "name": "jack"

  }

]

上面的list1是使用JsonHierarchicalStreamDriver 转换的，当然你也可以使用JettisonMappedXmlDriver驱动进行转换；用JettisonMappedXmlDriver转换后，你会发现格式不同而且没有根属性。

4、 Map转换json

@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("[email protected]");

    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));

}

运行后结果如下：

======JsonHierarchicalStreamDriver==== Map >>>> JaonString=========

{"map": [

  [

    "No.3",

    {

      "id": 0,

      "name": "jack"

    }

  ],

  [

    "No.1",

    {

      "id": 1,

      "name": "jack",

      "email": "[email protected]",

      "address": "china",

      "birthday": {

        "birthday": "2010-11-22"

      }

    }

  ],

  [

    "No.2",

    {

      "id": 2,

      "name": "tom",

      "email": "[email protected]",

      "address": "china",

      "birthday": {

        "birthday": "2010-11-21"

      }

    }

  ]

]}

[

  [

    "No.3",

    {

      "id": 0,

      "name": "jack"

    }

  ],

  [

    "No.1",

    {

      "id": 1,

      "name": "jack",

      "email": "[email protected]",

      "address": "china",

      "birthday": {

        "birthday": "2010-11-22"

      }

    }

  ],

  [

    "No.2",

    {

      "id": 2,

      "name": "tom",

      "email": "[email protected]",

      "address": "china",

      "birthday": {

        "birthday": "2010-11-21"

      }

    }

  ]

]

5、 将JSON转换java对象

/**

 * <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

    //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":"[email protected]","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\": \"[email protected]\"," +

            "\"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

}

运行后结果如下：

haha#1#address#2010-11-22#email

{"list": [{"id": 1,"name": "haha","email": "email","address": "address","birthday": {"birthday": "2010-11-22"}},

{"id": 2,"name": "tom","email": "[email protected]","address": "china","birthday": {"birthday": "2010-11-22"}}]}

0

JSON到Java的转换是fromXML方法。