XML 处理利器 : XStream
XStream 概述
XStream 是一套简洁易用的开发类库，用于将Java对象序列化为XML或者将XML反序列化为JAVA对象，是JAVA对象和XML之间一个双向转换器。
举例
采用User用户对象和LoginLog登录日志对象作为XStream实例转换对象. 例子简单，直接贴代码了.
User.java
package com.baobaotao.domain;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Map;
public class User implements Serializable {
private int userId;
private String userName;
private String password;
private int credits;
private String lastIp;
private Date lastVisit;
private List logs;
private Map datas;
public List<LoginLog> getLogs() {
return logs;
}
public void setLogs(List logs) {
this.logs = logs;
}
public int getUserId() {
return userId;
}
public void setUserId(int userId) {
this.userId = userId;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public int getCredits() {
return credits;
}
public void setCredits(int credits) {
this.credits = credits;
}
public String getLastIp() {
return lastIp;
}
public void setLastIp(String lastIp) {
this.lastIp = lastIp;
}
public Date getLastVisit() {
return lastVisit;
}
public void setLastVisit(Date lastVisit) {
this.lastVisit = lastVisit;
}
public void addLoginLog(LoginLog log){
if(this.logs==null){
logs = new ArrayList<LoginLog>();
}
logs.add(log);
}
public Map getDatas() {
return datas;
}
public void setDatas(Map datas) {
this.datas = datas;
}
}
LoginLog.java
package com.baobaotao.domain;
import java.io.Serializable;
import java.util.Date;
public class LoginLog implements Serializable {
private int loginLogId;
private int userId;
private String ip;
private Date loginDate;
public int getLoginLogId() {
return loginLogId;
}
public void setLoginLogId(int loginLogId) {
this.loginLogId = loginLogId;
}
public int getUserId() {
return userId;
}
public void setUserId(int userId) {
this.userId = userId;
}
public String getIp() {
return ip;
}
public void setIp(String ip) {
this.ip = ip;
}
public Date getLoginDate() {
return loginDate;
}
public void setLoginDate(Date loginDate) {
this.loginDate = loginDate;
}
}
下面就开始使用XStream进行对象与 XML之间的转换.
package com.baobaotao.oxm.xtream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.Date;
import com.baobaotao.domain.LoginLog;
import com.baobaotao.domain.User;
import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.io.xml.DomDriver;
public class XStreamSample {
private static XStream xstream;
static{
//创建XStream实例并指定一个XML 解析器
xstream=new XStream(new DomDriver());
}
//初始化转换对象
public static User getUser(){
LoginLog log1=new LoginLog();
log1.setIp("192.168.1.91");
log1.setLoginDate(new Date());
User user=new User();
user.setUserId(1);
user.setUserName("xstream");
user.addLoginLog(log1);
return user;
}
//Java 对象转换成XML
public static void objectToXML() throws Exception{
//获取转换User对象的实例
User user=getUser();
//实例化一个文件输出流
FileOutputStream fileOutputStream=new FileOutputStream("XStreamSample.xml");
//将User对象转换为XML,并保存到指定文件
xstream.toXML(user,fileOutputStream);
}
//XML转换为Java对象
public static User XMLToObject() throws Exception{
//实例化一个文件输入流
FileInputStream inputStream=new FileInputStream("XStreamSample.xml");
//将XML文件输入流转化为对象
User user=(User) xstream.fromXML(inputStream);
for(LoginLog log :user.getLogs()){
if(log!=null){
System.out.println("访问IP:"+log.getIp());
}
}
}
}
编写测试类
package com.baobaotao.oxm.xstream;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotNull;
import java.io.BufferedReader;
import java.io.FileReader;
import org.junit.Test;
import com.baobaotao.domain.LoginLog;
import com.baobaotao.domain.User;
import com.baobaotao.oxm.xtream.XStreamSample;
public class TestXStreamSample {
@Test
public void objectToXml()throws Exception {
XStreamSample.objectToXML();
FileReader reader = new FileReader("XStreamSample.xml");
BufferedReader br = new BufferedReader(reader);
StringBuffer sb = new StringBuffer("");
String s;
while ((s = br.readLine()) != null) {
sb.append(s);
}
System.out.println(sb.toString());
reader.close();
br.close();
// assertXpathExists("//com.baobaotao.domain.User",sb.toString());
// assertXpathExists("//credits",sb.toString());
// assertXpathExists("//userName",sb.toString());
// assertXpathExists("//com.baobaotao.domain.LoginLog",sb.toString());
}
@Test
public void xmlToObject()throws Exception {
XStreamSample.objectToXML();
User u = XStreamSample.XMLToObject();
assertNotNull(u);
assertEquals("xstream", u.getUserName());
for (LoginLog log : u.getLogs()) {
assertNotNull(log);
assertNotNull(log.getIp());
assertNotNull(log.getLoginDate());
}
}
}
生成的XML文件如下：
<com.baobaotao.domain.User>
<userId>1</userId>
<userName>xstream</userName>
<credits>0</credits>
<logs>
<com.baobaotao.domain.LoginLog>
<loginLogId>0</loginLogId>
<userId>0</userId>
<ip>192.168.1.91</ip>
<loginDate>2015-03-25 07:44:05.783 UTC</loginDate>
</com.baobaotao.domain.LoginLog>
</logs>
</com.baobaotao.domain.User>使用XStream 别名
在默认情况下，Java对象映射到XML的映射，是Java对象属性名对应XML的元素名，Java类的全名对应XML根元素的名字。在实际的应用中，如果XML和Java类都已经存在相应的名字，在进行转换时，需要设置别名进行映射。
XStream别名配置包含三种情况:
类别名，用alias(String name ,Class type);
类成员别名，用aliasField(String alias,Class definedIn,String fieldName);yo
类成员作为属性别名，用aliasAttribute(Class definedIn,String attributeName,String alias) ,单独命名没有意义，还要通过useAttributeFor(Class definedIn,String fieldName) 应用到某个类上。
package com.baobaotao.oxm.xtream.alias;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.Date;
import com.baobaotao.domain.LoginLog;
import com.baobaotao.domain.User;
import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.io.xml.DomDriver;
/**
* 别名
* @author yulei
*/
public class XStreamAliasSample {
private static XStream xstream;
static {
xstream=new XStream(new DomDriver());
//设置类别名，默认为当前类名称加上包名
xstream.alias("loginLog", LoginLog.class);
xstream.alias("user", User.class);
//设置类成员别名
xstream.aliasField("id", User.class, "userId");
//把LoginLog的userId属性视为XML属性，默认为XML的元素
xstream.aliasAttribute(LoginLog.class, "userId","id");
xstream.useAttributeFor(LoginLog.class, "userId");
//去掉集合类型生成XML的父节点，即忽略XML中的<logs></logs>标记
xstream.addImplicitCollection(User.class,"logs");
}
//初始化转换对象
public static User getUser(){
LoginLog log1=new LoginLog();
log1.setIp("192.168.1.91");
log1.setLoginDate(new Date());
User user=new User();
user.setUserId(1);
user.setUserName("xstream");
user.addLoginLog(log1);
return user;
}
//Java 对象转换成XML
public static void objectToXML() throws Exception{
//获取转换User对象的实例
User user=getUser();
//实例化一个文件输出流
FileOutputStream fileOutputStream=new FileOutputStream("XStreamSample.xml");
//将User对象转换为XML,并保存到指定文件
xstream.toXML(user,fileOutputStream);
}
//XML转换为Java对象
public static User XMLToObject() throws Exception{
//实例化一个文件输入流
FileInputStream inputStream=new FileInputStream("XStreamSample.xml");
//将XML文件输入流转化为对象
User user=(User) xstream.fromXML(inputStream);
for(LoginLog log :user.getLogs()){
if(log!=null){
System.out.println("访问IP:"+log.getIp());
}
}
return user;
}
}
