简单使用XStream

Stream
1.什么作用
*可以把JavaBean转换为（序列化为）xml
2.XStream的jar
*核心jar：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属性
>xstream.useAttributeFor(Province.class,"name"):把Province类的名为name成员，生成<province>元素的属性
*去除Collection类型的成员：我们只需要Collection的内容，而不需要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，它的内容还会生成元素）的属性不生成元素
*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中不会生成City类中的名为description的元素

package cn.itcast.demo1;

public class City {

    private String name;//市民
    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;
    }
    public City(String name, String description) {
        super();
        this.name = name;
        this.description = description;
    }
    public City() {
        super();
    }
    @Override
    public String toString() {
        return "City [name=" + name + ", description=" + description + "]";
    }

}

City.java

package cn.itcast.demo1;

import java.util.ArrayList;
import java.util.List;

public class Province {
    private String name;
    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 Province(String name, List<City> cities) {
        super();
        this.name = name;
        this.cities = cities;
    }
    public Province() {
        super();
        // TODO Auto-generated constructor stub
    }

    public void addCity(City city){
        cities.add(city);
    }

}

Province.java

package cn.itcast.demo1;

import java.util.ArrayList;
import java.util.List;

import org.junit.Test;

import com.thoughtworks.xstream.XStream;

public class Demo1 {
    public List<Province> getProvinceList(){
        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>
  <cn.itcast.demo1.Province>
    <name>北京</name>
    <cities>
      <cn.itcast.demo1.City>
        <name>东城区</name>
        <description>DongChengQu</description>
      </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=getProvinceList();
        /*
         * 创建XStream对象
         * 调用toXML将集合转换成字符串对象
         */
        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，让List类型对应<china>元素
     *  默认Province类型对应<cn.itcast.demo1.province>,希望它对应<province>
     *  默认City类型对应<cn.itcast.demo1.City>,希望它对应<city>
     */
    /*
<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=getProvinceList();
        XStream xstream=new XStream();
        /*
         * 给指定的类型指定别名
         */
        xstream.alias("china",List.class);
        xstream.alias("province", Province.class);
        xstream.alias("city", City.class);
        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>
</china>
     */
    @Test
    public void fun3(){
        List<Province> proList=getProvinceList();
        XStream xstream=new XStream();

        xstream.alias("china", List.class);
        xstream.alias("province", Province.class);
        xstream.alias("city", City.class);

        /*
         * 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);
    }

    /*
     <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>
     */
    /*
     * 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=getProvinceList();
        XStream xstream=new XStream();

        xstream.alias("china", List.class);
        xstream.alias("province", Province.class);
        xstream.alias("city", City.class);
        xstream.useAttributeFor(Province.class, "name");

        /*
         * 去除<cities>这样的Collection类型的属性
         * 去除Province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);
    }

    /*
     <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>
     */
    /*
     * 去除不想要的javabean属性
     * 就是让某些javabean属性不生成xml元素
     */
    @Test
    public void fun5(){
        List<Province> proList=getProvinceList();
        XStream xstream=new XStream();

        xstream.alias("china", List.class);
        xstream.alias("province", Province.class);
        xstream.alias("city", City.class);
        xstream.useAttributeFor(Province.class, "name");
        xstream.addImplicitCollection(Province.class, "cities");

        /*
         * 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);
    }

}

Demo1.java