android 中XML和對象轉換利器Xstream的使用

XStream框架:

雖說pull dom dom4j等優秀的xml解析工具使用非常廣泛,但對於復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幹的沖動,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?現在有瞭XStream,一切將變得美好,永遠告別原始手工作坊,讓你輕松的享受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。一定程度上限制瞭對Java對象的描述,不能讓xml完全體現到對Java對象的描述。這裡將會介紹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,隻需要提供相關的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 https://blog.csdn.net/IBM_hoojo

 * @email hoojo_@126.com

 * @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("jack@email.com");

        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>jack@email.com</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>jack@email.com</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("tom@125.com");

        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簽

        //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設置為父類(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>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");

這個設置的話,會出現一個List節點包裹著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,隻會在beans元素中出現name、student這2個xml元素標簽;

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。上面采用的id引用,<student reference="3"/>這個引用瞭id=3的那個student標簽元素;

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);

        //啟用Annotation

        //xstream.autodetectAnnotations(true);

        xstream.alias("student", Student.class);

        fail(xstream.toXML(c));

    } catch (Exception e) {

        e.printStackTrace();

    }

}

當啟用annotation或是對某個特定的類啟用annotation時,上面的classes這個類才有效果。如果不啟用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>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>

當啟用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>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("tom@125.com");

        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>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復雜的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("tom@125.com");

        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#jack@email.com

==========XML >>> List===========

size:3

jack#1#china#2010-11-22#jack@email.com

tom#2#china#2010-11-22#tom@125.com

jack#0#null#null#null

==========XML >>> Map===========

size:3

No.3:jack#0#null#null#null

No.1:jack#1#china#2010-11-22#jack@email.com

No.2:tom#2#china#2010-11-22#tom@125.com

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傢一一嘗試。用法類似~這裡就不一樣贅述。

四、XStream對JSON的支持

xStream對JSON也有非常好的支持,它提供瞭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":"jack@email.com","address":"china","birthday":[{},"2010-11-22"]}}

JSON的轉換和XML的轉換用法一樣,隻是創建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。這裡會降到兩個驅動,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對象為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": "jack@email.com",

  "address": "china",

  "birthday": {

    "birthday": "2010-11-22"

  }

}}

{

  "id": 1,

  "name": "jack",

  "email": "jack@email.com",

  "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,它隻是將類名作為一個屬性,將對象作為該屬性的一個值。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("tom@125.com");

    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": "jack@email.com",

    "address": "china",

    "birthday": {

      "birthday": "2010-11-22"

    }

  },

  {

    "id": 2,

    "name": "tom",

    "email": "tom@125.com",

    "address": "china",

    "birthday": {

      "birthday": "2010-11-22"

    }

  },

  {

    "id": 0,

    "name": "jack"

  }

]}

#[

  {

    "id": 1,

    "name": "jack",

    "email": "jack@email.com",

    "address": "china",

    "birthday": {

      "birthday": "2010-11-22"

    }

  },

  {

    "id": 2,

    "name": "tom",

    "email": "tom@125.com",

    "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("tom@125.com");

    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": "jack@email.com",

      "address": "china",

      "birthday": {

        "birthday": "2010-11-22"

      }

    }

  ],

  [

    "No.2",

    {

      "id": 2,

      "name": "tom",

      "email": "tom@125.com",

      "address": "china",

      "birthday": {

        "birthday": "2010-11-21"

      }

    }

  ]

]}

[

  [

    "No.3",

    {

      "id": 0,

      "name": "jack"

    }

  ],

  [

    "No.1",

    {

      "id": 1,

      "name": "jack",

      "email": "jack@email.com",

      "address": "china",

      "birthday": {

        "birthday": "2010-11-22"

      }

    }

  ],

  [

    "No.2",

    {

      "id": 2,

      "name": "tom",

      "email": "tom@125.com",

      "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":"tom@125.com","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\": \"tom@125.com\"," +

            "\"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:

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": "tom@125.com","address": "china","birthday": {"birthday": "2010-11-22"}}]}

0

JSON到Java的轉換是fromXML方法。

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