XStream
1. 什么作用 * 可以把JavaBean转换为（序列化为）xml
2. XStream的jar包
* 核心JAR包：xstream-1.4.7.jar；
* 必须依赖包：xpp3_min-1.1.4c（XML Pull Parser，一款速度很快的XML解析器）；
3. 使用步骤
* XStream xstream = new XStream();
* String xmlStr = xstream.toXML(javabean);
4. 使用细节
* 别名：把类型对应的元素名修改了
> xstream.alias("china", List.class)：让List类型生成的元素名为china
> xstream.alias("province", Province.class)：让Province类型生成的元素名为province
* 使用为属性：默认类的成员，生成的是元素的子元素！我们希望让类的成员生成元素的属性
> xstream.useAttributeFor(Province.class, "name")：把Province类的名为name成员，生成<province>元素的name属性
* 去除Collection类型的成名：我们只需要Collection的内容，而不希望Collection本身也生成一个元素
> xstream.addImplicitCollection(Province.class, "cities")：让Province类的名为cities(它是List类型的，它的内容还会生成元素)的成名不生成元素
* 去除类的指定成名，让其不生成xml元素
> xstream.omitField(City.class, "description")：在生成的xml中不会出现City类的名为description的对应的元素！
具体实例
package cn.itcast.demo1;
import java.util.ArrayList;
import java.util.List;
import org.junit.Test;
import com.thoughtworks.xstream.XStream;
/**
* 演示XStream
* @author cxf
*
*/
public class Demo1 {
// 返回javabean集合
public List<Province> getProinvceList() {
Province p1 = new Province();
p1.setName("北京");
p1.addCity(new City("东城区", "DongChengQu"));
p1.addCity(new City("昌平区", "ChangPingQu"));
Province p2 = new Province();
p2.setName("辽宁");
p2.addCity(new City("沈阳", "shenYang"));
p2.addCity(new City("葫芦岛", "huLuDao"));
List<Province> provinceList = new ArrayList<Province>();
provinceList.add(p1);
provinceList.add(p2);
return provinceList;
}
/**
<list> --> List类型显示list
<cn.itcast.demo1.Province> --> javabean的类型为Province，它元素的名称为类的完整名
<name>北京</name> --> javabean的属性名
<cities> --> javabean的属性名
<cn.itcast.demo1.City> --> 类名
<name>东城区</name> --> 属性名
<description>DongChengQu</description> --> 属性名
</cn.itcast.demo1.City>
<cn.itcast.demo1.City>
<name>昌平区</name>
<description>ChangPingQu</description>
</cn.itcast.demo1.City>
</cities>
</cn.itcast.demo1.Province>
<cn.itcast.demo1.Province>
<name>辽宁</name>
<cities>
<cn.itcast.demo1.City>
<name>沈阳</name>
<description>shenYang</description>
</cn.itcast.demo1.City>
<cn.itcast.demo1.City>
<name>葫芦岛</name>
<description>huLuDao</description>
</cn.itcast.demo1.City>
</cities>
</cn.itcast.demo1.Province>
</list>
*/
@Test
public void fun1() {
List<Province> proList = getProinvceList();
/*
* 创建XStream对象
* 调用toXML把集合转换成xml字符串
*/
XStream xstream = new XStream();
String s = xstream.toXML(proList);
System.out.println(s);
}
/*
* 别名(alias)
* 希望：
* * 默认List类型对应<list>元素，希望让List类型对应<china>元素
* * 默认Province类型对应<cn.itcast.demo1.Province>，希望让它对应<province>
* * 默认City类型对应<cn.itcast.demo1.City>，希望它对应<city>元素
*/
/*
<china>
<province>
<name>北京</name>
<cities>
<city>
<name>东城区</name>
<description>DongChengQu</description>
</city>
<city>
<name>昌平区</name>
<description>ChangPingQu</description>
</city>
</cities>
</province>
<province>
<name>辽宁</name>
<cities>
<city>
<name>沈阳</name>
<description>shenYang</description>
</city>
<city>
<name>葫芦岛</name>
<description>huLuDao</description>
</city>
</cities>
</province>
</china>
*/
@Test
public void fun2() {
List<Province> proList = getProinvceList();
XStream xstream = new XStream();
/*
* 给指定的类型指定别名
*/
xstream.alias("china", List.class);//给List类型指定别名为china
xstream.alias("province", Province.class);//给Province指定别名为province
xstream.alias("city", City.class);//给City类型指定别名为city
String s = xstream.toXML(proList);
System.out.println(s);
}
/*
* 默认javabean的属性都会生成子元素，而现在希望生成元素的属性
*/
/*
<china>
<province name="北京">
<cities>
<city>
<name>东城区</name>
<description>DongChengQu</description>
</city>
<city>
<name>昌平区</name>
<description>ChangPingQu</description>
</city>
</cities>
</province>
<province name="辽宁">
<cities>
<city>
<name>沈阳</name>
<description>shenYang</description>
</city>
<city>
<name>葫芦岛</name>
<description>huLuDao</description>
</city>
</cities>
</province>
*/
@Test
public void fun3() {
List<Province> proList = getProinvceList();
XStream xstream = new XStream();
xstream.alias("china", List.class);//给List类型指定别名为china
xstream.alias("province", Province.class);//给Province指定别名为province
xstream.alias("city", City.class);//给City类型指定别名为city
/*
* 把Province类型的name属性，生成<province>元素的属性
*/
xstream.useAttributeFor(Province.class, "name");
String s = xstream.toXML(proList);
System.out.println(s);
}
/*
* 去除List类型的属性，只把list中的元素生成xml元素
*/
/*
<china>
<province name="北京">
<city>
<name>东城区</name>
<description>DongChengQu</description>
</city>
<city>
<name>昌平区</name>
<description>ChangPingQu</description>
</city>
</province>
<province name="辽宁">
<city>
<name>沈阳</name>
<description>shenYang</description>
</city>
<city>
<name>葫芦岛</name>
<description>huLuDao</description>
</city>
</province>
</china>
*/
@Test
public void fun4() {
List<Province> proList = getProinvceList();
XStream xstream = new XStream();
xstream.alias("china", List.class);//给List类型指定别名为china
xstream.alias("province", Province.class);//给Province指定别名为province
xstream.alias("city", City.class);//给City类型指定别名为city
xstream.useAttributeFor(Province.class, "name");//把Province类型的name属性，生成<province>元素的属性
/*
* 去除<cities>这样的Collection类型的属性
* 去除Provice类的名为cities的List类型的属性！
*/
xstream.addImplicitCollection(Province.class, "cities");
String s = xstream.toXML(proList);
System.out.println(s);
}
/**
* 去除不想要的javabean属性
* 就是让某引起javabean属性，不生成对应的xml元素！
*/
/*
<china>
<province name="北京">
<city>
<name>东城区</name>
</city>
<city>
<name>昌平区</name>
</city>
</province>
<province name="辽宁">
<city>
<name>沈阳</name>
</city>
<city>
<name>葫芦岛</name>
</city>
</province>
</china>
*/
@Test
public void fun5() {
List<Province> proList = getProinvceList();
XStream xstream = new XStream();
xstream.alias("china", List.class);//给List类型指定别名为china
xstream.alias("province", Province.class);//给Province指定别名为province
xstream.alias("city", City.class);//给City类型指定别名为city
xstream.useAttributeFor(Province.class, "name");//把Province类型的name属性，生成<province>元素的属性
xstream.addImplicitCollection(Province.class, "cities");//去除Provice类的名为cities的List类型的属性！
/*
* 让City类的，名为description属性不生成对应的xml元素
*/
xstream.omitField(City.class, "description");
String s = xstream.toXML(proList);
System.out.println(s);
}
}
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