Xstream完美转换XML,JSON

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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:

https://nexus.codehaus.org/content/repositories/releases/com/thoughtworks/xstream/xstream-distribution/1.3.1/xstream-distribution-1.3.1-bin.zip

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;需要的jar如下:

2、 测试用例代码

package com.hoo.test;@H_403_35@ 
  
@H_403_35@ 
  
import java.io.IOException;@H_403_35@ 
  
import java.io.ObjectInputStream;@H_403_35@ 
  
import java.io.ObjectOutputStream;@H_403_35@ 
  
import java.io.StringReader;@H_403_35@ 
  
import java.io.Writer;@H_403_35@ 
  
import java.util.ArrayList;@H_403_35@ 
  
import java.util.HashMap;@H_403_35@ 
  
import java.util.Iterator;@H_403_35@ 
  
import java.util.List;@H_403_35@ 
  
import java.util.Map;@H_403_35@ 
  
import java.util.Set;@H_403_35@ 
  
import org.codehaus.jettison.json.JSONException;@H_403_35@ 
  
import org.junit.After;@H_403_35@ 
  
import org.junit.Before;@H_403_35@ 
  
import org.junit.Test;@H_403_35@ 
  
import com.hoo.entity.Birthday;@H_403_35@ 
  
import com.hoo.entity.Classes;@H_403_35@ 
  
import com.hoo.entity.ListBean;@H_403_35@ 
  
import com.hoo.entity.Student;@H_403_35@ 
  
import com.thoughtworks.xstream.XStream;@H_403_35@ 
  
import com.thoughtworks.xstream.io.HierarchicalStreamWriter;@H_403_35@ 
  
import com.thoughtworks.xstream.io.json.JettisonMappedXmlDriver;@H_403_35@ 
  
import com.thoughtworks.xstream.io.json.JsonHierarchicalStreamDriver;@H_403_35@ 
  
import com.thoughtworks.xstream.io.json.JsonWriter;@H_403_35@ 
  
@H_403_35@ 
  
/**@H_403_35@ 
  
 * <b>function:</b>Java对象和XML字符串的相互转换@H_403_35@ 
  
 * jar-lib-version: xstream-1.3.1@H_403_35@ 
  
 * @author hoojo@H_403_35@ 
  
 * @createDate Nov 27,2010 12:15:15 PM@H_403_35@ 
  
 * @file XStreamTest.java@H_403_35@ 
  
 * @package com.hoo.test@H_403_35@ 
  
 * @project WebHttpUtils@H_403_35@ 
  
 * @blog http://blog.csdn.net/IBM_hoojo@H_403_35@ 
  
 * @email hoojo_@126.com@H_403_35@ 
  
 * @version 1.0@H_403_35@ 
  
 */@H_403_35@ 
  
@SuppressWarnings("unchecked")@H_403_35@ 
  
public class XStreamTest {@H_403_35@ 
  
    @H_403_35@ 
  
    private XStream xstream = null;@H_403_35@ 
  
    private ObjectOutputStream  out = null;@H_403_35@ 
  
private ObjectInputStream in = null;@H_403_35@ 
  
private Student bean = null;@H_403_35@ 
  
     * <b>function:</b>初始化资源准备@H_403_35@ 
  
     * @author hoojo@H_403_35@ 
  
     * @createDate Nov 27,2010 12:16:28 PM@H_403_35@ 
  
     */@H_403_35@ 
  
    @Before@H_403_35@ 
  
void init() {@H_403_35@ 
  
        try {@H_403_35@ 
  
            xstream = new XStream();@H_403_35@ 
  
            //xstream = new XStream(new DomDriver()); // 需要xpp3 jar@H_403_35@ 
  
        } catch (Exception e) {@H_403_35@ 
  
            e.printStackTrace();@H_403_35@ 
  
        }@H_403_35@ 
  
        bean = new Student();@H_403_35@ 
  
        bean.setAddress("china");@H_403_35@ 
  
        bean.setEmail("jack@email.com");@H_403_35@ 
  
        bean.setId(1);@H_403_35@ 
  
        bean.setName("jack");@H_403_35@ 
  
        Birthday day = new Birthday();@H_403_35@ 
  
        day.setBirthday("2010-11-22");@H_403_35@ 
  
        bean.setBirthday(day);@H_403_35@ 
  
    }@H_403_35@ 
  
    @H_403_35@ 
  
     * <b>function:</b>释放对象资源@H_403_35@ 
  
403_35@ 
  
    @After@H_403_35@ 
  
void destory() {@H_403_35@ 
  
        xstream = null;@H_403_35@ 
  
        bean = null;@H_403_35@ 
  
        if (out != null) {@H_403_35@ 
  
                out.flush();@H_403_35@ 
  
                out.close();@H_403_35@ 
  
            }@H_403_35@ 
  
if (in != null) {@H_403_35@ 
  
                in.close();@H_403_35@ 
  
            }@H_403_35@ 
  
catch (IOException e) {@H_403_35@ 
  
        System.gc();@H_403_35@ 
  
    }@H_403_35@ 
  
final void fail(String string) {@H_403_35@ 
  
        System.out.println(string);@H_403_35@ 
  
void failRed(String string) {@H_403_35@ 
  
        System.err.println(string);@H_403_35@ 
  
}@H_403_35@ 
 

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

@H_879_301@package com.hoo.entity;@H_403_35@
class Student {@H_403_35@ 
  
private int id;@H_403_35@ 
  
private String name;@H_403_35@ 
  
private String email;@H_403_35@ 
  
private String address;@H_403_35@ 
  
private Birthday birthday;@H_403_35@ 
  
//getter、setter@H_403_35@ 
  
public String toString() {@H_403_35@ 
  
return this.name + "#" + this.id + this.address + this.birthday + this.email;@H_403_35@ 
  
}@H_403_35@ 
 

二、Java转换成XML

1、 JavaBean转换XM

* <b>function:</b>Java对象转换成XML字符串@H_403_35@
403_35@ 
  
@Test@H_403_35@ 
  
void writeBean2XML() {@H_403_35@ 
  
        fail("------------Bean->XML------------");@H_403_35@ 
  
        fail(xstream.toXML(bean));@H_403_35@ 
  
"重命名后的XML");@H_403_35@ 
  
//类重命名@H_403_35@ 
  
//xstream.alias("account",Student.class);@H_403_35@ 
  
//xstream.alias("生日",Birthday.class);@H_403_35@ 
  
//xstream.aliasField("生日",Student.class,"birthday");@H_403_35@ 
  
//fail(xstream.toXML(bean));@H_403_35@ 
  
//属性重命名@H_403_35@ 
  
        xstream.aliasField("邮件",Student.class,"email");@H_403_35@ 
  
//包重命名@H_403_35@ 
  
        xstream.aliasPackage("hoo",128)">"com.hoo.entity");@H_403_35@ 
  
    }         e.printStackTrace();@H_403_35@ 
  
 看结果中的第一份xml内容,是没有经过然后修改重命名的文档,按照原样输出。文档中的第二份文档的package经过重命名,email属性也经过重命名以及类名也可以进行重命名的。

运行后结果如下:

------------Bean->XML------------@H_403_35@
<com.hoo.entity.Student>@H_403_35@ 
  
  <id>1</id  <name>jack</name<email>jack@email.com</email<address>china</<birthday>2010-11-22</birthday</com重命名后的XML@H_403_35@ 
  
<hoo<邮件</邮件</hoo>@H_403_35@ 
 

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@H_403_35@
403_35@ 
  
void writeList2XML() {@H_403_35@ 
  
//修改元素名称@H_403_35@ 
  
        xstream.alias("beans",ListBean.class);@H_403_35@ 
  
        xstream.alias("student",244)">        fail("----------List-->XML----------");@H_403_35@ 
  
        ListBean listBean = new ListBean();@H_403_35@ 
  
        listBean.setName("this is a List Collection");@H_403_35@ 
  
        @H_403_35@ 
  
        List<Object> list = new ArrayList<Object>();@H_403_35@ 
  
        list.add(bean);@H_403_35@ 
  
        list.add(bean);//引用bean@H_403_35@ 
  
//list.add(listBean);//引用listBean,父元素@H_403_35@ 
  
        @H_403_35@ 
  
        bean =         bean.setAddress(        bean.setEmail("tom@125.com");@H_403_35@ 
  
        bean.setId(2);@H_403_35@ 
  
        bean.setName("tom");@H_403_35@ 
  
        Birthday day = new Birthday(        listBean.setList(list);@H_403_35@ 
  
//将ListBean中的集合设置空元素,即不显示集合元素标签@H_403_35@ 
  
//xstream.addImplicitCollection(ListBean.class,"list");@H_403_35@ 
  
//设置reference模型@H_403_35@ 
  
//xstream.setMode(XStream.NO_REFERENCES);//不引用@H_403_35@ 
  
        xstream.setMode(XStream.ID_REFERENCES);//id引用@H_403_35@ 
  
//xstream.setMode(XStream.XPATH_ABSOLUTE_REFERENCES);//绝对路径引用@H_403_35@ 
  
          @H_403_35@ 
  
//将name设置为父类(Student)的元素的属性@H_403_35@ 
  
        xstream.useAttributeFor(Student."name");@H_403_35@ 
  
        xstream.useAttributeFor(Birthday."birthday");@H_403_35@ 
  
//修改属性的name@H_403_35@ 
  
        xstream.aliasAttribute("姓名",128)">"生日",Birthday.      @H_403_35@ 
  
        fail(xstream.toXML(listBean));@H_403_35@ 
  
    }         e.printStackTrace();@H_403_35@ 
  
 上面的代码运行后,结果如下:

----------List-->XML----------@H_403_35@
<beans id="1">this is a List Collection<list id="2"<student id="3" 姓名="jack"            <birthday id="4" 生日="2010-11-22"/</student<student reference="3"/<student id="5" 姓名="tom">2>tom@125<birthday id="6" 生日="2010-11-22"/</list</beans 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、 在JavaBean中添加Annotation注解进行重命名设置

先看看JavaBean的代码

@H_879_301@import
java.util.Arrays;@H_403_35@
import java.util.Calendar;@H_403_35@ 
  
import java.util.GregorianCalendar;@H_403_35@ 
  
import com.thoughtworks.xstream.annotations.XStreamAlias;@H_403_35@ 
  
import com.thoughtworks.xstream.annotations.XStreamAsAttribute;@H_403_35@ 
  
import com.thoughtworks.xstream.annotations.XStreamConverter;@H_403_35@ 
  
import com.thoughtworks.xstream.annotations.XStreamImplicit;@H_403_35@ 
  
import com.thoughtworks.xstream.annotations.XStreamOmitField;@H_403_35@ 
  
@XStreamAlias("class")@H_403_35@ 
  
class Classes {@H_403_35@ 
  
/*@H_403_35@ 
  
     * 设置属性显示@H_403_35@ 
  
    @XStreamAsAttribute@H_403_35@ 
  
    @XStreamAlias("名称")@H_403_35@ 
  
     * 忽略@H_403_35@ 
  
    @XStreamOmitField@H_403_35@ 
  
int number;@H_403_35@ 
  
    @XStreamImplicit(itemFieldName = "Students")@H_403_35@ 
  
private List<Student> students;@H_403_35@ 
  
    @SuppressWarnings("unused")@H_403_35@ 
  
    @XStreamConverter(SingleValueCalendarConverter.class)@H_403_35@ 
  
private Calendar created = new GregorianCalendar();@H_403_35@ 
  
public Classes(){}@H_403_35@ 
  
public Classes(String name,Student... stu) {@H_403_35@ 
  
this.name = name;@H_403_35@ 
  
this.students = Arrays.asList(stu);@H_403_35@ 
  
 SingleValueCalendarConverter.java这个是一个类型转换器

@H_879_301@import java.util.Date;@H_403_35@
import com.thoughtworks.xstream.converters.Converter;@H_403_35@ 
  
import com.thoughtworks.xstream.converters.MarshallingContext;@H_403_35@ 
  
import com.thoughtworks.xstream.converters.UnmarshallingContext;@H_403_35@ 
  
import com.thoughtworks.xstream.io.HierarchicalStreamReader;@H_403_35@ 
  
class SingleValueCalendarConverter implements Converter {@H_403_35@ 
  
     void marshal(Object source,HierarchicalStreamWriter writer,@H_403_35@ 
  
                MarshallingContext context) {@H_403_35@ 
  
            Calendar calendar = (Calendar) source;@H_403_35@ 
  
            writer.setValue(String.valueOf(calendar.getTime().getTime()));@H_403_35@ 
  
public Object unmarshal(HierarchicalStreamReader reader,244)">                UnmarshallingContext context) {@H_403_35@ 
  
            GregorianCalendar calendar =             calendar.setTime(new Date(Long.parseLong(reader.getValue())));@H_403_35@ 
  
            return calendar;@H_403_35@ 
  
        }@H_403_35@ 
  
        @SuppressWarnings(boolean canConvert(Class type) {@H_403_35@ 
  
return type.equals(GregorianCalendar. 再看看测试用例代码

@Test@H_403_35@
void writeList2XML4Annotation() {@H_403_35@ 
  
        failRed("---------annotation Bean --> XML---------");@H_403_35@ 
  
        Student stu =         stu.setName(        Classes c = new Classes("一班",bean,stu);@H_403_35@ 
  
        c.setNumber(2);@H_403_35@ 
  
//对指定的类使用Annotation@H_403_35@ 
  
//xstream.processAnnotations(Classes.class);@H_403_35@ 
  
//启用Annotation@H_403_35@ 
  
//xstream.autodetectAnnotations(true);@H_403_35@ 
  
        fail(xstream.toXML(c));@H_403_35@ 
  
 当启用annotation或是对某个特定的类启用annotation时,上面的classes这个类才有效果。如果不启用annotation,运行后结果如下:

---------annotation Bean --> XML---------@H_403_35@
.Classes>一班<number</number<students class="java.util.Arrays$ArrayList"<a class="student-array"<student          >0</a</students<created<time>1303292056718</time<timezone>Asia/Shanghai</timezone</created 当启用annotation后xstream.processAnnotations(Classes.class),结果如下:

<class 名称="一班"<Students</Students>1303292242937</class 4、 Map集合转换xml文档

* <b>function:</b>Java Map集合转XML@H_403_35@
403_35@ 
  
void writeMap2XML() {@H_403_35@ 
  
        failRed("---------Map --> XML---------");@H_403_35@ 
  
        Map<String,Student> map = new HashMap<String,Student>();@H_403_35@ 
  
        map.put("No.1",bean);//put@H_403_35@ 
  
        map.put("No.2",128)">"No.3",128)">"key",String.        xstream.useAttributeFor(Student."id");@H_403_35@ 
  
        xstream.useAttributeFor("birthday",244)">        fail(xstream.toXML(map));@H_403_35@ 
  
---------Map --map<entry<key>No.3</key<student id="0"</entry>No.1<student id="1"<birthday birthday="2010-11-22"/>No.2<student id="2">tom 5、 用OutStream输出流写XML

* <b>function:</b>用OutStream输出流写XML@H_403_35@
403_35@ 
  
void writeXML4OutStream() {@H_403_35@ 
  
        out = xstream.createObjectOutputStream(System.out);@H_403_35@ 
  
        Student stu =         stu.setName(        Classes c =         c.setNumber(2);@H_403_35@ 
  
"---------ObjectOutputStream # JavaObject--> XML---------");@H_403_35@ 
  
        out.writeObject(stu);@H_403_35@ 
  
        out.writeObject("2010-05-33"));@H_403_35@ 
  
        out.write(22);//byte@H_403_35@ 
  
        out.writeBoolean(true);@H_403_35@ 
  
        out.writeFloat(22.f);@H_403_35@ 
  
        out.writeUTF("hello");@H_403_35@ 
  
 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--object-stream.Birthday>2010-05-33<byte>22</byte<boolean>true</booleanfloat>22.0<string>hello</string 三、XML内容转换Java对象

1、 用InputStream将XML文档转换成java对象

* <b>function:</b>用InputStream将XML文档转换成java对象 @H_403_35@
 * 需要额外的jar xpp3-main.jar@H_403_35@ 
  
403_35@ 
  
void readXML4InputStream() {@H_403_35@ 
  
        String s = "<object-stream><com.hoo.entity.Student><id>0</id><name>jack</name>" +@H_403_35@ 
  
"</com.hoo.entity.Student><com.hoo.entity.Birthday><birthday>2010-05-33</birthday>" +@H_403_35@ 
  
          "</com.hoo.entity.Birthday><byte>22</byte><boolean>true</boolean><float>22.0</float>" +@H_403_35@ 
  
"<string>hello</string></object-stream>";@H_403_35@ 
  
"---------ObjectInputStream## XML --> javaObject---------");@H_403_35@ 
  
        StringReader reader = new StringReader(s);@H_403_35@ 
  
        in = xstream.createObjectInputStream(reader);@H_403_35@ 
  
        Student stu = (Student) in.readObject();@H_403_35@ 
  
        Birthday b = (Birthday) in.readObject();@H_403_35@ 
  
byte i = in.readByte();@H_403_35@ 
  
boolean bo = in.readBoolean();@H_403_35@ 
  
float f = in.readFloat();@H_403_35@ 
  
        String str = in.readUTF();@H_403_35@ 
  
        System.out.println(stu);@H_403_35@ 
  
        System.out.println(b);@H_403_35@ 
  
        System.out.println(i);@H_403_35@ 
  
        System.out.println(bo);@H_403_35@ 
  
        System.out.println(f);@H_403_35@ 
  
        System.out.println(str);@H_403_35@ 
  
 读取后,转换的Java对象,结果如下:

---------ObjectInputStream## XML --> javaObject---------@H_403_35@
jack#0#null#null#null@H_403_35@ 
  
2010-05-33@H_403_35@ 
  
22@H_403_35@ 
  
true@H_403_35@ 
  
22.0@H_403_35@ 
  
hello@H_403_35@ 
 

2、 将xml文档转换成Java对象

* <b>function:</b>将XML字符串转换成Java对象@H_403_35@
403_35@ 
  
void readXml2Object() {@H_403_35@ 
  
"-----------Xml >>> Bean--------------");@H_403_35@ 
  
        Student stu = (Student) xstream.fromXML(xstream.toXML(bean));@H_403_35@ 
  
        fail(stu.toString());@H_403_35@ 
  
        List<Student> list = new ArrayList<Student>();@H_403_35@ 
  
//add@H_403_35@ 
  
        list.add(bean);"==========XML >>> List===========");@H_403_35@ 
  
        List<Student> studetns = (List<Student>) xstream.fromXML(xstream.toXML(list));@H_403_35@ 
  
"size:" + studetns.size());//3@H_403_35@ 
  
for (Student s : studetns) {@H_403_35@ 
  
            fail(s.toString());@H_403_35@ 
  
"==========XML >>> Map===========");@H_403_35@ 
  
403_35@ 
  
"size:" + maps.size());        Set<String> key = maps.keySet();@H_403_35@ 
  
        Iterator<String> iter = key.iterator();@H_403_35@ 
  
while (iter.hasNext()) {@H_403_35@ 
  
            String k = iter.next();@H_403_35@ 
  
            fail(k + ":" + map.get(k));@H_403_35@ 
  
-----------Xml >>> Bean--------------@H_403_35@ 
  
jack#1#china#2010-11-22#jack@email.com@H_403_35@ 
  
==========XML >>> List===========@H_403_35@ 
  
size:3@H_403_35@ 
  
jack#1#china#2010-11-22#jack@email.com@H_403_35@ 
  
tom#2#china#2010-11-22#tom@125.com@H_403_35@ 
  
jack#0#null#null#null@H_403_35@ 
  
==========XML >>> Map===========@H_403_35@ 
  
size:3@H_403_35@ 
  
No.3:jack#0#null#null#null@H_403_35@ 
  
No.1:jack#1#china#2010-11-22#jack@email.com@H_403_35@ 
  
No.2:tom#2#china#2010-11-22#tom@125.com@H_403_35@ 
 

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@H_403_35@
 * 需要添加jettison jar@H_403_35@ 
  
403_35@ 
  
void writeEntity2JETTSON() {@H_403_35@ 
  
    failRed("=======JettisonMappedXmlDriver===JavaObject >>>> JaonString=========");@H_403_35@ 
  
    xstream = new XStream(new JettisonMappedXmlDriver());@H_403_35@ 
  
    xstream.setMode(XStream.NO_REFERENCES);@H_403_35@ 
  
    xstream.alias(    fail(xstream.toXML(bean));@H_403_35@ 
  
=======JettisonMappedXmlDriver===JavaObject >>>> JaonString=========@H_403_35@ 
  
{"student":{"id":1,128)">"name":"jack",128)">"email":"jack@email.com",128)">"address":"china",128)">"birthday":[{},128)">"2010-11-22"]}}@H_403_35@ 
 

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@H_403_35@
 * 转换java对象为JSON字符串@H_403_35@ 
  
403_35@ 
  
void writeEntiry2JSON() {@H_403_35@ 
  
"======JsonHierarchicalStreamDriver====JavaObject >>>> JaonString=========");@H_403_35@ 
  
new JsonHierarchicalStreamDriver());@H_403_35@ 
  
//xstream.setMode(XStream.NO_REFERENCES);@H_403_35@ 
  
"-------Object >>>> JSON---------");@H_403_35@ 
  
    fail(xstream.toXML(bean));@H_403_35@ 
  
//failRed("========JsonHierarchicalStreamDriver==删除根节点=========");@H_403_35@ 
  
//删除根节点@H_403_35@ 
  
new JsonHierarchicalStreamDriver() {@H_403_35@ 
  
public HierarchicalStreamWriter createWriter(Writer out) {@H_403_35@ 
  
new JsonWriter(out,JsonWriter.DROP_ROOT_MODE);@H_403_35@ 
  
    });@H_403_35@ 
  
======JsonHierarchicalStreamDriver====JavaObject >>>> JaonString=========@H_403_35@ 
  
-------Object >>>> JSON---------@H_403_35@ 
  
{"student": {@H_403_35@ 
  
"id": 1,128)">"name": "email": "address": "birthday": {@H_403_35@ 
  
"birthday": "2010-11-22"@H_403_35@ 
  
  }@H_403_35@ 
  
}}@H_403_35@ 
  
{@H_403_35@ 
  
  }@H_403_35@ 
  
 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

@H_879_301@void writeList2JSON() {@H_403_35@
    JsonHierarchicalStreamDriver driver = new JsonHierarchicalStreamDriver();@H_403_35@ 
  
    xstream = new XStream(driver);@H_403_35@ 
  
//xstream = new XStream(new JettisonMappedXmlDriver());//转换错误@H_403_35@ 
  
    List<Student> list =     list.add(bean);    bean =     bean.setAddress(    bean.setEmail(    bean.setId(2);@H_403_35@ 
  
    bean.setName(    Birthday day =     bean.setBirthday(day);@H_403_35@ 
  
    list.add(bean);    bean =     fail(xstream.toXML(list));@H_403_35@ 
  
    xstream.alias( 运行后结果如下

##{"list": [@H_403_35@
  {@H_403_35@ 
  
  },244)">  {@H_403_35@ 
  
"id": 2,128)">"tom",128)">"tom@125.com",244)">  },128)">"id": 0,128)">"jack"@H_403_35@ 
  
]}@H_403_35@ 
  
#[@H_403_35@ 
  
]@H_403_35@ 
 

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

@H_879_301@void
writeMap2JSON() {@H_403_35@
"======JsonHierarchicalStreamDriver==== Map >>>> JaonString=========");@H_403_35@ 
  
//xstream = new XStream(new JettisonMappedXmlDriver());@H_403_35@ 
  
    Map<String,monospace; direction:ltr; font-size:10pt; overflow:visible; background-color:white">    map.put(    bean.setBirthday("2010-11-21"));@H_403_35@ 
  
    bean.setName(    fail(xstream.toXML(map));@H_403_35@ 
  
    });@H_403_35@ 
  
======JsonHierarchicalStreamDriver==== Map >>>> JaonString=========@H_403_35@ 
  
"map": [@H_403_35@ 
  
  [@H_403_35@ 
  
    {@H_403_35@ 
  
  ],244)">  [@H_403_35@ 
  
    {@H_403_35@ 
  
      }@H_403_35@ 
  
"2010-11-21"@H_403_35@ 
  
  ]@H_403_35@ 
  
]}@H_403_35@ 
  
[@H_403_35@ 
  
  ],244)">      }@H_403_35@ 
  
  ]@H_403_35@ 
  
 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;@H_403_35@
 * JsonHierarchicalStreamDriver读取JSON字符串到java对象出错@H_403_35@ 
  
403_35@ 
  
 * @throws JSONException@H_403_35@ 
  
void readJSON2Object() throws JSONException {@H_403_35@ 
  
    String json = "{\"student\": {" +@H_403_35@ 
  
"\"id\": 1," +@H_403_35@ 
  
"\"name\": \"haha\",128)">"\"email\": \"email\",128)">"\"address\": \"address\",128)">"\"birthday\": {" +@H_403_35@ 
  
"\"birthday\": \"2010-11-22\"" +@H_403_35@ 
  
"}" +@H_403_35@ 
  
"}}";@H_403_35@ 
  
//JsonHierarchicalStreamDriver读取JSON字符串到java对象出错,但JettisonMappedXmlDriver可以@H_403_35@ 
  
    fail(xstream.fromXML(json).toString());@H_403_35@ 
  
//JettisonMappedXmlDriver转换List集合出错,但JsonHierarchicalStreamDriver可以转换正确@H_403_35@ 
  
//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":"tom@125.com","address":"china","2010-11-22"]}}@H_403_35@ 
  
    json = "{\"list\": [{" +@H_403_35@ 
  
                         "},{" +@H_403_35@ 
  
"\"id\": 2,128)">"\"name\": \"tom\",128)">"\"email\": \"tom@125.com\",128)">"\"address\": \"china\",128)">"}]}";@H_403_35@ 
  
    System.out.println(json);//用js转换成功@H_403_35@ 
  
    List list = (List) xstream.fromXML(json);@H_403_35@ 
  
    System.out.println(list.size());//0好像转换失败@H_403_35@ 
  
haha#1#address#2010-11-22#email@H_403_35@ 
  
"list": [{"haha",128)">"email",128)">"address",128)">"birthday": {"2010-11-22"}},128)">"2010-11-22"}}]}@H_403_35@ 
  
0@H_403_35@ 
 

JSON到Java的转换是fromXML方法


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

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