XStream框架:
雖說pull dom dom4j等優秀的xml解析工具使用非常廣泛,但對於複雜龐大的數據交互來說,使用它們無疑讓你倍加痛苦,你可能大部分精力都放在無聊繁瑣的解析和拼裝上,如果接口稍微改動,更令你有股辭職不相干的衝動,或許你更傾向選擇JSON,但有時候你還是不得不面對JSON,XML,對象之間的轉化的煩惱,如何用最簡單的辦法一統混亂的局面,讓你全心全意做設計寫業務?現在有了XStream,一切將變得美好,永遠告別原始手工作坊,讓你輕鬆的享受coding帶來的快樂
xStream可以輕易的將Java對象和xml文檔相互轉換，而且可以修改某個特定的屬性和節點名稱，而且也支持json的轉換；
json-lib這個框架 ,Jackson這個框架， 它們都完美支持JSON，但是對xml的支持還不是很好。一定程度上限制了對Java對象的描述，不能讓xml完全體現到對Java對象的描述。這裏將會介紹xStream對JSON、XML的完美支持。xStream不僅對XML的轉換非常友好，而且提供annotation註解，可以在JavaBean中完成對xml節點、屬性的描述。以及對JSON也支持，只需要提供相關的JSONDriver就可以完成轉換。
一.準備環境
首先去 Xstream官方網址 下載最新的jar包,此jar包可以再java和android環境下都適用
二.測試用例代碼
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對象和XML字符串的相互轉換
* 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>初始化資源準備
* @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>釋放對象資源
* @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);
}
}
通過XStream對象的toXML方法就可以完成Java對象到XML的轉換，toXML方法還有2個相同簽名的方法，需要傳遞一個流。然後通過流來完成xml信息的輸出。
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轉換成XML
1、 JavaBean轉換XM
/**
* <b>function:</b>Java對象轉換成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("重命名後的XML");
//類重命名
//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));
//屬性重命名
xstream.aliasField("郵件", Student.class, "email");
//包重命名
xstream.aliasPackage("hoo", "com.hoo.entity");
fail(xstream.toXML(bean));
} catch (Exception e) {
e.printStackTrace();
}
}
看結果中的第一份xml內容，是沒有經過然後修改或重命名的文檔，按照原樣輸出。文檔中的第二份文檔的package經過重命名，email屬性也經過重命名以及類名也可以進行重命名的。
運行後結果如下：
------------Bean->XML------------
<com.hoo.entity.Student>
<id>1</id>
<name>jack</name>
<email>[email protected]</email>
<address>china</address>
<birthday>
<birthday>2010-11-22</birthday>
</birthday>
</com.hoo.entity.Student>
重命名後的XML
<hoo.Student>
<id>1</id>
<name>jack</name>
<郵件>[email protected]</郵件>
<address>china</address>
<birthday>
<birthday>2010-11-22</birthday>
</birthday>
</hoo.Student>
2、 將List集合轉換成xml文檔
/**
* <b>function:</b>將Java的List集合轉換成XML對象
* @author hoojo
* @createDate Nov 27, 2010 12:20:07 PM
*/
@Test
public void writeList2XML() {
try {
//修改元素名稱
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);
//將ListBean中的集合設置空元素，即不顯示集合元素標籤
//xstream.addImplicitCollection(ListBean.class, "list");
//設置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);//絕對路徑引用
//將name設置爲父類（Student）的元素的屬性
xstream.useAttributeFor(Student.class, "name");
xstream.useAttributeFor(Birthday.class, "birthday");
//修改屬性的name
xstream.aliasAttribute("姓名", "name");
xstream.aliasField("生日", Birthday.class, "birthday");
fail(xstream.toXML(listBean));
} catch (Exception e) {
e.printStackTrace();
}
}
上面的代碼運行後，結果如下：
----------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>[email protected]</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>[email protected]</email>
<address>china</address>
<birthday id="6" 生日="2010-11-22"/>
</student>
</list>
</beans>
如果不加xstream.addImplicitCollection(ListBean.class, "list");
這個設置的話，會出現一個List節點包裹着Student節點元素。添加addImplicitCollection可以忽略這個list節點元素。那麼上面的list節點就不存在，只會在beans元素中出現name、student這2個xml元素標籤；
setMode是設置相同的對象的引用方式，如果設置XStream.NO_REFERENCES就是不引用，會輸出2分相同的Student元素。如果是XStream.ID_REFERENCES會引用相同的那個對象的id屬性，如果是XStream.XPATH_ABSOLUTE_REFERENCES引用，那麼它將顯示xpath路徑。上面採用的id引用，<student reference="3"/>這個引用了id=3的那個student標籤元素；
useAttributeFor是設置某個節點顯示到父節點的屬性中，也就是將指定class中的指定屬性，在這個class元素節點的屬性中顯示。
如：<student><name>hoojo</name></student>
設置好後就是這樣的結果：<student name=”hoojo”></student>
aliasAttribute是修改屬性名稱。
3、 在JavaBean中添加Annotation註解進行重命名設置
先看看JavaBean的代碼
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 {
/*
* 設置屬性顯示
*/
@XStreamAsAttribute
@XStreamAlias("名稱")
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這個是一個類型轉換器
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);
}
}
再看看測試用例代碼
@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);
//對指定的類使用Annotation
//xstream.processAnnotations(Classes.class);
//啓用Annotation
//xstream.autodetectAnnotations(true);
xstream.alias("student", Student.class);
fail(xstream.toXML(c));
} catch (Exception e) {
e.printStackTrace();
}
}
當啓用annotation或是對某個特定的類啓用annotation時，上面的classes這個類纔有效果。如果不啓用annotation，運行後結果如下：
---------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>[email protected]</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>
當啓用annotation後xstream.processAnnotations(Classes.class)，結果如下：
---------annotation Bean --> XML---------
<class 名稱="一班">
<Students>
<id>1</id>
<name>jack</name>
<email>[email protected]</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集合轉換xml文檔
/**
* <b>function:</b>Java Map集合轉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();
}
}
運行後結果如下：
---------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>[email protected]</email>
<address>china</address>
<birthday birthday="2010-11-22"/>
</student>
</entry>
<entry>
<key>No.2</key>
<student id="2">
<name>tom</name>
<email>[email protected]</email>
<address>china</address>
<birthday birthday="2010-11-22"/>
</student>
</entry>
</map>
5、 用OutStream輸出流寫XML
/**
* <b>function:</b>用OutStream輸出流寫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();
}
}
使用輸出流後，可以通過流對象完成xml的構建，即使沒有JavaBean對象，你可以用流來構建一個複雜的xml文檔，運行後結果如下：
---------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內容轉換Java對象
1、 用InputStream將XML文檔轉換成java對象
/**
* <b>function:</b>用InputStream將XML文檔轉換成java對象
* 需要額外的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();
}
}
讀取後，轉換的Java對象，結果如下：
---------ObjectInputStream## XML --> javaObject---------
jack#0#null#null#null
2010-05-33
22
true
22.0
hello
2、 將xml文檔轉換成Java對象
/**
* <b>function:</b>將XML字符串轉換成Java對象
* @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();
}
}
運行後結果如下：
-----------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]
怎麼樣，成功的完成XML到JavaBean、List、Map的轉換，更多對象轉換還需要大家一一嘗試。用法類似~這裏就不一樣贅述。
四、XStream對JSON的支持
xStream對JSON也有非常好的支持，它提供了2個模型驅動。用這2個驅動可以完成Java對象到JSON的相互轉換。使用JettisonMappedXmlDriver驅動，將Java對象轉換成json，需要添加jettison.jar
1、 用JettisonMappedXmlDriver完成Java對象到JSON的轉換
/**
* <b>function:</b>XStream結合JettisonMappedXmlDriver驅動，轉換Java對象到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));
}
運行後結果如下：
=======JettisonMappedXmlDriver===JavaObject >>>> JaonString=========
{"student":{"id":1,"name":"jack","email":"[email protected]","address":"china","birthday":[{},"2010-11-22"]}}
JSON的轉換和XML的轉換用法一樣，只是創建XStream需要傳遞一個參數，這個參數就是xml到JSON映射轉換的驅動。這裏會降到兩個驅動，分別是JettisonMappedXmlDriver、JsonHierarchicalStreamDriver。
2、 JsonHierarchicalStreamDriver完成Java對象到JSON的轉換
/**
* <b>function:</b>用XStream結合JsonHierarchicalStreamDriver驅動
* 轉換java對象爲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==刪除根節點=========");
//刪除根節點
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));
}
運行後結果如下：
======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轉換默認會給轉換後的對象添加一個根節點，但是在構建JsonHierarchicalStreamDriver驅動的時候，你可以重寫createWriter方法，刪掉根節點。
看上面的結果，一個是默認帶根節點的JSON對象，它只是將類名作爲一個屬性，將對象作爲該屬性的一個值。而另一個沒有帶根屬性的JSON就是通過重寫createWriter方法完成的。
3、 將List集合轉換成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());//轉換錯誤
//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==刪除根節點=========");
//刪除根節點
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));
}
運行後結果如下
======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 轉換的，當然你也可以使用JettisonMappedXmlDriver驅動進行轉換；用JettisonMappedXmlDriver轉換後，你會發現格式不同而且沒有根屬性。
4、 Map轉換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==刪除根節點=========");
//刪除根節點
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));
}
運行後結果如下：
======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、 將JSON轉換java對象
/**
* <b>function:</b>JsonHierarchicalStreamDriver可以將簡單的json字符串轉換成java對象，list、map轉換不成功；
* JsonHierarchicalStreamDriver讀取JSON字符串到java對象出錯
* @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讀取JSON字符串到java對象出錯，但JettisonMappedXmlDriver可以
xstream = new XStream(new JettisonMappedXmlDriver());
xstream.alias("student", Student.class);
fail(xstream.fromXML(json).toString());
//JettisonMappedXmlDriver轉換List集合出錯，但JsonHierarchicalStreamDriver可以轉換正確
//JettisonMappedXmlDriver 轉換的字符串 {"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轉換成功
List list = (List) xstream.fromXML(json);
System.out.println(list.size());//0好像轉換失敗
}
運行後結果如下： www.2cto.com
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的轉換是fromXML方法。
三.android源碼實例
上面的代碼是不是還不夠過癮?Xstream原則上只要是符合XML和JSON語法規範的都能可以轉換成對象形式.
作者：shimiso