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 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>初始化资源准备
* @author hoojo
* @createDate Nov 27,2010 12:16:28 PM
*/
@Before
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>释放对象资源
* @author hoojo
*/
@After
void destory() {
xstream = null;
bean = null;
try {
if (out != null) {
out.flush();
out.close();
}
if (in != null) {
in.close();
}
catch (IOException e) {
System.gc();
}
final void fail(String string) {
System.out.println(string);
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
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@Testvoid writeBean2XML() {fail("------------Bean->XML------------");
fail(xstream.toXML(bean));"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");//fail(xstream.toXML(bean));//属性重命名xstream.aliasField("邮件",Student.class,"email");//包重命名xstream.aliasPackage("hoo",128)">"com.hoo.entity");
} 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:
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void writeList2XML() {//修改元素名称xstream.alias("beans",ListBean.class);"student",255)">class);"----------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new Student();"china");"tom@125.com");bean.setId(2);"tom");new Birthday( 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."name");
xstream.useAttributeFor(Birthday."birthday");
//修改属性的namexstream.aliasAttribute("姓名",128)">"name");
"生日",Birthday."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">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元素节点的属性中显示。
如:<student><name>hoojo</name></student>
设置好后就是这样的结果:<student name=”hoojo”></student>
3、 在JavaBean中添加Annotation注解进行重命名设置
先看看JavaBean的代码
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")
class Classes {/** 设置属性显示@XStreamAsAttribute@XStreamAlias("名称")
/** 忽略@XStreamOmitFieldint 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、setterSingleValueCalendarConverter.java这个是一个类型转换器import java.util.Calendar;import java.util.Date;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;class SingleValueCalendarConverter implements Converter {
void marshal(Object source,HierarchicalStreamWriter writer,
MarshallingContext context) {Calendar calendar = (Calendar) source;writer.setValue(String.valueOf(calendar.getTime().getTime()));public Object unmarshal(HierarchicalStreamReader reader,monospace; direction:ltr; font-size:10pt; overflow:visible"> UnmarshallingContext context) {GregorianCalendar calendar = new GregorianCalendar();
calendar.setTime(new Date(Long.parseLong(reader.getValue())));
return calendar;}@SuppressWarnings(boolean canConvert(Class type) {
return type.equals(GregorianCalendar. 再看看测试用例代码
@Testvoid writeList2XML4Annotation() {failRed("---------annotation Bean --> XML---------");
Student stu = stu.setName( 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);fail(xstream.toXML(c));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---------.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XMLvoid writeMap2XML() {"---------Map --> XML---------");Map<String,Student> map = new HashMap<String,Student>();
map.put("No.1",bean);//put"No.2",0)">//put"jack");"No.3",128)">"key",String."id");
xstream.useAttributeFor("birthday",monospace; direction:ltr; font-size:10pt; overflow:visible"> fail(xstream.toXML(map));
---------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XMLvoid writeXML4OutStream() {out = xstream.createObjectOutputStream(System.out);c.setNumber(2);"---------ObjectOutputStream # JavaObject--> XML---------");out.writeObject(stu);out.writeObject("2010-05-33"));
out.write(22);//byte
out.writeBoolean(true);out.writeFloat(22.f);out.writeUTF("hello");
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* 需要额外的jar xpp3-main.jar* @author hoojo*/void readxml4InputStream() {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>";"---------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);读取后,转换的Java对象,结果如下:---------ObjectInputStream## XML --> javaObject---------jack#0#null#null#null2010-05-3322true22.0hello2、 将xml文档转换成Java对象
* <b>function:</b>将XML字符串转换成Java对象void readxml2Object() {"-----------Xml >>> Bean--------------");Student stu = (Student) xstream.fromXML(xstream.toXML(bean));fail(stu.toString());List<Student> list = new ArrayList<Student>();
//add//add"==========XML >>> List===========");List<Student> studetns = (List<Student>) xstream.fromXML(xstream.toXML(list));"size:" + studetns.size());//3
for (Student s : studetns) {fail(s.toString());"==========XML >>> Map===========");"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));
-----------Xml >>> Bean--------------jack#1#china#2010-11-22#jack@email.com==========XML >>> List===========size:3jack#1#china#2010-11-22#jack@email.comtom#2#china#2010-11-22#tom@125.comjack#0#null#null#null==========XML >>> Map===========size:3No.3:jack#0#null#null#nullNo.1:jack#1#china#2010-11-22#jack@email.comNo.2:tom#2#china#2010-11-22#tom@125.com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 jarvoid writeEntity2JETTSON() {failRed("=======JettisonMappedXmlDriver===JavaObject >>>> JaonString=========");
xstream = new XStream(new JettisonMappedXmlDriver());xstream.setMode(XStream.NO_REFERENCES);xstream.alias( fail(xstream.toXML(bean));
=======JettisonMappedXmlDriver===JavaObject >>>> JaonString========={"student":{"id":1,128)">"name":"jack",128)">"email":"jack@email.com",128)">"address":"china",128)">"birthday":[{},128)">"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void writeEntiry2JSON() {"======JsonHierarchicalStreamDriver====JavaObject >>>> JaonString=========");new JsonHierarchicalStreamDriver());//xstream.setMode(XStream.NO_REFERENCES);"-------Object >>>> JSON---------");fail(xstream.toXML(bean));//failRed("========JsonHierarchicalStreamDriver==删除根节点=========");//删除根节点new JsonHierarchicalStreamDriver() {public HierarchicalStreamWriter createWriter(Writer out) {new JsonWriter(out,JsonWriter.DROP_ROOT_MODE);});======JsonHierarchicalStreamDriver====JavaObject >>>> JaonString=========-------Object >>>> JSON---------"student": {"id": 1,"name": "email": "address": "birthday": {"birthday": "2010-11-22"
}}}{"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
void writeList2JSON() {JsonHierarchicalStreamDriver driver = new JsonHierarchicalStreamDriver();
new XStream(driver);//xstream = new XStream(new JettisonMappedXmlDriver());//转换错误List<Student> list = new ArrayList<Student>();
list.add(bean); bean = bean.setAddress( bean.setEmail( bean.setId(2);
bean.setName( Birthday day = bean.setBirthday(day);
fail(xstream.toXML(list));运行后结果如下##{"list": [{},monospace; direction:ltr; font-size:10pt; overflow:visible"> {"id": 2,128)">"tom",128)">"tom@125.com",128)">"id": 0,128)">"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
void writeMap2JSON() {"======JsonHierarchicalStreamDriver==== Map >>>> JaonString=========");//xstream = new XStream(new JettisonMappedXmlDriver());Map<String,monospace; direction:ltr; font-size:10pt; overflow:visible"> map.put( bean.setBirthday("2010-11-21"));
fail(xstream.toXML(map));//failRed("========JsonHierarchicalStreamDriver==删除根节点=========");//删除根节点new JsonHierarchicalStreamDriver() {public HierarchicalStreamWriter createWriter(Writer out) {});======JsonHierarchicalStreamDriver==== Map >>>> JaonString========="map": [[{],monospace; direction:ltr; font-size:10pt; overflow:visible"> [{}"2010-11-21"]]}["jack"}"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* @throws JSONExceptionvoid readJSON2Object() throws JSONException {
String json = "{\"student\": {" +
"\"id\": 1," +"\"name\": \"haha\"," +"\"email\": \"email\",128)">"\"address\": \"address\",128)">"\"birthday\": {" +"\"birthday\": \"2010-11-22\"" +"}" +"}}";//JsonHierarchicalStreamDriver读取JSON字符串到java对象出错,但JettisonMappedXmlDriver可以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":"tom@125.com","address":"china","2010-11-22"]}}json = "{\"list\": [{" +
"},{" +
"\"id\": 2,128)">"\"name\": \"tom\",128)">"\"email\": \"tom@125.com\",128)">"\"address\": \"china\",128)">"}]}";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haha#1#address#2010-11-22#email"list": [{"haha",128)">"email",128)">"address",128)">"birthday": {"2010-11-22"}},128)">"2010-11-22"}}]}0JSON到Java的转换是fromXML方法。
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