xStream完美转换XML、JSON
排版不好，请看原文链接：http://www.cnblogs.com/hoojo/archive/2011/04/22/2025197.html
xStream完美转换XML、JSON
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：
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;
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.ListBean;
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 [email protected]
* @version 1.0
*/
@SuppressWarnings("unchecked"
)
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("[email protected]"
);
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);
}
}
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;
public class Student {
private int id;
private
String name;
private
String email;
private
String address;
private
Birthday birthday;
//getter、setter
public
String toString() {
return this .name + "#" + this .id + "#" + this .address + "#" + this .birthday + "#" + this .email;
}
}
二、 Java 转换成 XML
1、 JavaBean转换XM
/**
* <b>function:</b>Java对象转换成XML字符串
* @author hoojo
* @createDate Nov 27, 2010 12:19:01 PM
*/
@Test
public void writeBean2XML() {
try
{
fail("------------Bean->XML------------"
);
fail(xstream.toXML(bean));
fail("重命名后的XML"
);
//类重命名
//xstream.alias("account", Student.class);
//xstream.alias("生日", Birthday.class);
//xstream.aliasField("生日", Student.class, "birthday");
//xstream.aliasField("生日", Birthday.class, "birthday");
//fail(xstream.toXML(bean));
//属性重命名
xstream.aliasField("邮件" , Student.class , "email" );
//包重命名
xstream.aliasPackage("hoo" , "com.hoo.entity" );
fail(xstream.toXML(bean));
} catch
(Exception e) {
e.printStackTrace();
}
}
看结果中的第一份xml内容，是没有经过然后修改或重命名的文档，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------------
< com.hoo .entity .Student >
< id> 1< /id>
< name> jack< /name>
< email> jack@email.com < /email>
< address > china< /address >
< birthday>
< birthday> 2010-11-22< /birthday>
< /birthday>
< /com.hoo .entity .Student >
重命名后的XML
< hoo.Student >
< id> 1< /id>
< name> jack< /name>
< 邮件> jack@email.com < /邮件>
< address > china< /address >
< birthday>
< birthday> 2010-11-22< /birthday>
< /birthday>
< /hoo.Student >
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
*/
@Test
public void writeList2XML() {
try
{
//修改元素名称
xstream.alias("beans" , ListBean.class );
xstream.alias("student" , Student.class );
fail("----------List-->XML----------"
);
ListBean listBean = new
ListBean();
listBean.setName("this is a List Collection"
);
List<Object> list = new
ArrayList<Object>();
list.add(bean);
list.add(bean);//引用bean
//list.add(listBean);//引用listBean，父元素
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);
listBean.setList(list);
//将ListBean中的集合设置空元素，即不显示集合元素标签
//xstream.addImplicitCollection(ListBean.class, "list");
//设置reference模型
//xstream.setMode(XStream.NO_REFERENCES);//不引用
xstream.setMode(XStream.ID_REFERENCES);//id引用
//xstream.setMode(XStream.XPATH_ABSOLUTE_REFERENCES);//绝对路径引用
//将name设置为父类（Student）的元素的属性
xstream.useAttributeFor(Student.class , "name" );
xstream.useAttributeFor(Birthday.class , "birthday" );
//修改属性的name
xstream.aliasAttribute("姓名" , "name" );
xstream.aliasField("生日" , Birthday.class , "birthday" );
fail(xstream.toXML(listBean));
} catch
(Exception e) {
e.printStackTrace();
}
}
上面的代码运行后，结果如下：
----------List-->
XML----------
< beans id="1">
< name> this is a List Collection< /name>
< list id="2">
< student id="3" 姓名="jack">
< id> 1< /id>
< email> jack@email.com < /email>
< address > china< /address >
< birthday id="4" 生日="2010-11-22"/>
< /student>
< student reference="3"/>
< student id="5" 姓名="tom">
< id> 2< /id>
< email> tom@125.com < /email>
< address > china< /address >
< birthday id="6" 生日="2010-11-22"/>
< /student>
< /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、 在JavaBean中添加Annotation注解进行重命名设置
先看看JavaBean的代码
package
com.hoo.entity;
import
java.util.Arrays;
import
java.util.Calendar;
import
java.util.GregorianCalendar;
import
java.util.List;
import
com.thoughtworks.xstream.annotations.XStreamAlias;
import
com.thoughtworks.xstream.annotations.XStreamAsAttribute;
import
com.thoughtworks.xstream.annotations.XStreamConverter;
import
com.thoughtworks.xstream.annotations.XStreamImplicit;
import
com.thoughtworks.xstream.annotations.XStreamOmitField;
@XStreamAlias("class"
)
public class Classes {
/*
* 设置属性显示
*/
@XStreamAsAttribute
@XStreamAlias("名称"
)
private
String name;
/*
* 忽略
*/
@XStreamOmitField
private int number;
@XStreamImplicit(itemFieldName = "Students"
)
private
List<Student> students;
@SuppressWarnings("unused"
)
@XStreamConverter(SingleValueCalendarConverter.class
)
private Calendar created = new GregorianCalendar();
public
Classes(){}
public
Classes(String name, Student... stu) {
this
.name = name;
this
.students = Arrays.asList(stu);
}
//getter、setter
}
SingleValueCalendarConverter.java这个是一个类型转换器
package
com.hoo.entity;
import
java.util.Calendar;
import
java.util.Date;
import
java.util.GregorianCalendar;
import
com.thoughtworks.xstream.converters.Converter;
import
com.thoughtworks.xstream.converters.MarshallingContext;
import
com.thoughtworks.xstream.converters.UnmarshallingContext;
import
com.thoughtworks.xstream.io.HierarchicalStreamReader;
import
com.thoughtworks.xstream.io.HierarchicalStreamWriter;
public class SingleValueCalendarConverter implements Converter {
public void marshal(Object source, HierarchicalStreamWriter writer,
MarshallingContext context) {
Calendar calendar = (Calendar) source;
writer.setValue(String.valueOf(calendar.getTime().getTime()));
}
public
Object unmarshal(HierarchicalStreamReader reader,
UnmarshallingContext context) {
GregorianCalendar calendar = new
GregorianCalendar();
calendar.setTime(new
Date(Long.parseLong(reader.getValue())));
return
calendar;
}
@SuppressWarnings("unchecked"
)
public boolean canConvert(Class type) {
return type.equals(GregorianCalendar.class );
}
}
再看看测试用例代码
@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();
}
}
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---------
< com.hoo .entity .Classes >
< name> 一班< /name>
< number> 2< /number>
< students class="java.util .Arrays $ArrayList">
< a class="student-array">
< student>
< id> 1< /id>
< name> jack< /name>
< email> jack@email.com < /email>
< address > china< /address >
< birthday>
< birthday> 2010-11-22< /birthday>
< /birthday>
< /student>
< student>
< id> 0< /id>
< name> jack< /name>
< /student>
< /a>
< /students>
< created>
< time> 1303292056718< /time>
< timezone> Asia/Shanghai< /timezone>
< /created>
< /com.hoo .entity .Classes >
当启用annotation后xstream.processAnnotations(Classes.class)，结果如下：
---------annotation Bean -->
XML---------
< class 名称="一班">
< Students>
< id> 1< /id>
< name> jack< /name>
< email> jack@email.com < /email>
< address > china< /address >
< birthday>
< birthday> 2010-11-22< /birthday>
< /birthday>
< /Students>
< Students>
< id> 0< /id>
< name> jack< /name>
< /Students>
< created> 1303292242937< /created>
< /class>
4、 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
{
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("[email protected]"
);
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();
}
}
运行后结果如下：
---------Map -->
XML---------
< map >
< entry>
< key> No.3< /key>
< student id="0">
< name> jack< /name>
< /student>
< /entry>
< entry>
< key> No.1< /key>
< student id="1">
< name> jack< /name>
< email> jack@email.com < /email>
< address > china< /address >
< birthday birthday="2010-11-22"/>
< /student>
< /entry>
< entry>
< key> No.2< /key>
< student id="2">
< name> tom< /name>
< email> tom@125.com < /email>
< address > china< /address >
< birthday birthday="2010-11-22"/>
< /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、 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
* 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();
}
}
读取后，转换的Java对象，结果如下：
---------ObjectInputStream## XML --> javaObject---------
jack#0#null#null#null
2010-05-33
22
true
22.0
hello
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
* @author hoojo
* @createDate Nov 27, 2010 2:39:06 PM
*/
@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("[email protected]"
);
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();
}
}
运行后结果如下：
-----------Xml >>> Bean--------------
jack#1#china#2010-11-22#[email protected]
==========XML >>> List===========
size:3
jack#1#china#2010-11-22#[email protected]
tom#2#china#2010-11-22#[email protected]
jack#0#null#null#null
==========XML >>> Map===========
size:3
No.3:jack#0#null#null#null
No.1:jack#1#china#2010-11-22#[email protected]
No.2:tom#2#china#2010-11-22#[email protected]
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。