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！
应用实例：
import java.util.ArrayList;
import java.util.List;
import org.junit.Test;
import com.thoughtworks.xstream.XStream;
/**
* 演示XStream
*/
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;
}
@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
*/
@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
*/
@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
*/
@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！
*/
@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);
}
}
public class City {
private String name;//市名
private String description;//描述
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
@Override
public String toString() {
return "City [name=" + name + ", description=" + description + "]";
}
public City() {
super();
// TODO Auto-generated constructor stub
}
public City(String name, String description) {
super();
this.name = name;
this.description = description;
}
}
City
import java.util.ArrayList;
import java.util.List; public class Province {
private String name;// 省名
private List<City> cities = new ArrayList<City>(); public String getName() {
return name;
} public void setName(String name) {
this.name = name;
} public List<City> getCities() {
return cities;
} public void setCities(List<City> cities) {
this.cities = cities;
} public void addCity(City city) {
cities.add(city);
}
}
Province
fun1输出结果：
<list>
<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>
</list>
fun1
fun2输出结果：
<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>
fun2
fun3输出结果：
<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>
</china>
fun3
fun4输出结果：
<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>
fun4
fun5输出结果：
<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>
fun5