Xstream之常用方式与常用注解

示例代码 

Blog teamBlog = new Blog(new Author("Guilherme Silveira"));
teamBlog.add(new Entry("first","My first blog entry."));
eamBlog.add(new Entry("tutorial","Today we have developed a nice alias tutorial. Tell your friends! NOW!"));
XStream xstream = new XStream();
 System.out.println(xstream.toXML(teamBlog));

打印结果为: 

 <xtream.Blog>
  <writer>
    <name>Guilherme Silveira</name>
  </writer>
  <entries>
    <xtream.Entry>
      <title>first</title>
      <description>My first blog entry.</description>
    </xtream.Entry>
    <xtream.Entry>
      <title>tutorial</title>
      <description>Today we have developed a nice alias tutorial. Tell your friends! NOW!</description>
    </xtream.Entry>
  </entries>
</xtream.Blog>

以上节点就包含了包名,如包名很长,就很难看了,怎样才能重新命名这个节点呀！ 
以下的1,2设置效果一样 

1 //xstream.aliasPackage("", "xtream");
2 xstream.alias("blog", Blog.class);
3 xstream.alias("entry", Entry.class);

  
通过这样设置就完成了节点名称的设置.如下: 

<blog>
  <writer>
    <name>Guilherme Silveira</name>
  </writer>
  <entries>
    <entry>
      <title>first</title>
      <description>My first blog entry.</description>
    </entry>
    <entry>
      <title>tutorial</title>
      <description>Today we have developed a nice alias tutorial. Tell your friends! NOW!</description>
    </entry>
  </entries>
</blog>

修改子节点属性名称 
将writer属性名称修改为:autor 

xstream.aliasField("author", Blog.class, "writer");

输出如下: 

<blog>
  <author>
    <name>Guilherme Silveira</name>
  </author>
  <entries>
    <entry>
      <title>first</title>
      <description>My first blog entry.</description>
    </entry>
    <entry>
      <title>tutorial</title>
      <description>Today we have developed a nice alias tutorial. Tell your friends! NOW!</description>
    </entry>
  </entries>
</blog>

删除集合节点名称的设置 

xstream.addImplicitCollection(Blog.class, "entries");

输出如下: 

 <blog>
  <author>
    <name>Guilherme Silveira</name>
  </author>
  <entry>
    <title>first</title>
    <description>My first blog entry.</description>
  </entry>
  <entry>
    <title>tutorial</title>
    <description>Today we have developed a nice alias tutorial. Tell your friends! NOW!</description>
  </entry>
</blog>

将Blog类的元素设置为:它的节点属性 
//使用这个属性名作为节点上的元素 

xstream.useAttributeFor(Blog.class, "writer");

//重新命名 

xstream.aliasField("author", Blog.class, "writer");

//注册转换器 

xstream.registerConverter(new AuthorConverter());

转换器: 

import com.thoughtworks.xstream.converters.SingleValueConverter;
class AuthorConverter implements SingleValueConverter {
    //显示节点属性值
    public String toString(Object obj) {
        return ((Author) obj).getName();
    }

    public Object fromString(String name) {
        return new Author(name);
    }

    public boolean canConvert(Class type) {
        return type.equals(Author.class);
    }
}

显示结果: 

<blog author="Guilherme Silveira">
  <entry>
    <title>first</title>
    <description>My first blog entry.</description>
  </entry>
  <entry>
    <title>tutorial</title>
    <description>Today we have developed a nice alias tutorial. Tell your friends! NOW!</description>
  </entry>
</blog>

注解的使用方式,使用之前必须加上注解类才有作用: 

XStream xstream = new XStream();
xstream.processAnnotations(Blog.class);
xstream.processAnnotations(Entry.class);

1  @XStreamAlias注解可在类与属性上使用设置名称,相当于: xstream.alias("blog", Blog.class); 

@XStreamAlias("blog")
public class Blog {

    @XStreamAlias("author")
        private Author writer;

    .....
}

当然Entry类也要设置同样的类属性:@XStreamAlias("entity") 
2 @XStreamImplicit去集合节点名:相当于 xstream.addImplicitCollection(Blog.class, "entries"); 
3 @XStreamConverter(AuthorConverter.class),参见以上的转换器类相当于: 

xstream.useAttributeFor(Blog.class, "writer");
//重新命名
xstream.aliasField("author", Blog.class, "writer");
//注册转换器
xstream.registerConverter(new AuthorConverter());

要使用这个注解AuthorConverter必须符合二个条件 
a 必须要有个默认的无参构造函数 

public AuthorConverter() {

}

b 类声明必须为:public 

public class AuthorConverter implements SingleValueConverter {
 ...
}

不用注解这二点都可以不强制要求! 
完整代码如下: 

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.annotations.XStreamAlias;
import com.thoughtworks.xstream.annotations.XStreamAsAttribute;
import com.thoughtworks.xstream.annotations.XStreamConverter;
import com.thoughtworks.xstream.annotations.XStreamImplicit;
@XStreamAlias("blog")
public class Blog {

    @XStreamAsAttribute
    @XStreamAlias("author")
    @XStreamConverter(AuthorConverter.class)
    private Author writer;

    @XStreamImplicit
    private List entries = new ArrayList();

    public Blog(Author writer) {
        this.writer = writer;
    }

    public void add(Entry entry) {
        entries.add(entry);
    }

    public List getContent() {
        return entries;
    }

    public static void main(String[] args) {

        Blog teamBlog = new Blog(new Author("Guilherme Silveira"));
        teamBlog.add(new Entry("first", "My first blog entry."));
        teamBlog
                .add(new Entry("tutorial",
                        "Today we have developed a nice alias tutorial. Tell your friends! NOW!"));
        XStream xstream = new XStream();
        xstream.processAnnotations(Blog.class);
        xstream.processAnnotations(Entry.class);
        // 重新命名节点名
        // xstream.aliasPackage("", "xtream");
        /*
         * xstream.alias("blog", Blog.class); xstream.alias("entry",
         * Entry.class); //重新命名属性名 // xstream.aliasField("author", Blog.class,
         * "writer"); //去节点 xstream.addImplicitCollection(Blog.class,
         * "entries"); // xstream.useAttributeFor(Blog.class, "writer"); //
         * xstream.aliasField("author", Blog.class, "writer"); //
         * xstream.addImplicitCollection(Blog.class, "entries");
         * //使用这个属性名作为节点上的元素 xstream.useAttributeFor(Blog.class, "writer");
         * //重新命名 xstream.aliasField("author", Blog.class, "writer"); //注册转换器
         * xstream.registerConverter(new AuthorConverter());
         */
        System.out.println(xstream.toXML(teamBlog));
    }

}