Xstream之常用方式与常用注解

示例代码

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

打印结果为:

1. <xtream.Blog>
2. <writer>
3. <name>Guilherme Silveira</name>
4. </writer>
5. <entries>
6. <xtream.Entry>
7. <title>first</title>
8. <description>My first blog entry.</description>
9. </xtream.Entry>
10. <xtream.Entry>
11. <title>tutorial</title>
12. <description>Today we have developed a nice alias tutorial. Tell your friends! NOW!</description>
13. </xtream.Entry>
14. </entries>
15. </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. 1 //xstream.aliasPackage("", "xtream");
2. 2 xstream.alias("blog", Blog.class);
3. 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:

1. <blog>
2. <writer>
3. <name>Guilherme Silveira</name>
4. </writer>
5. <entries>
6. <entry>
7. <title>first</title>
8. <description>My first blog entry.</description>
9. </entry>
10. <entry>
11. <title>tutorial</title>
12. <description>Today we have developed a nice alias tutorial. Tell your friends! NOW!</description>
13. </entry>
14. </entries>
15. </blog>

修改子节点属性名称 
将writer属性名称修改为:autor

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

输出如下:

1. <blog>
2. <author>
3. <name>Guilherme Silveira</name>
4. </author>
5. <entries>
6. <entry>
7. <title>first</title>
8. <description>My first blog entry.</description>
9. </entry>
10. <entry>
11. <title>tutorial</title>
12. <description>Today we have developed a nice alias tutorial. Tell your friends! NOW!</description>
13. </entry>
14. </entries>
15. </blog>

删除集合节点名称的设置

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

输出如下:

1. <blog>
2. <author>
3. <name>Guilherme Silveira</name>
4. </author>
5. <entry>
6. <title>first</title>
7. <description>My first blog entry.</description>
8. </entry>
9. <entry>
10. <title>tutorial</title>
11. <description>Today we have developed a nice alias tutorial. Tell your friends! NOW!</description>
12. </entry>
13. </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

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

//重新命名

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

//注册转换器

1. xstream.registerConverter(new AuthorConverter());

转换器:

1. import com.thoughtworks.xstream.converters.SingleValueConverter;
2. class AuthorConverter implements SingleValueConverter {
3. //显示节点属性值
4. public String toString(Object obj) {
5. return ((Author) obj).getName();
6. }
7. public Object fromString(String name) {
8. return new Author(name);
9. }
10. public boolean canConvert(Class type) {
11. return type.equals(Author.class);
12. }
13. }

显示结果:

1. <blog author="Guilherme Silveira">
2. <entry>
3. <title>first</title>
4. <description>My first blog entry.</description>
5. </entry>
6. <entry>
7. <title>tutorial</title>
8. <description>Today we have developed a nice alias tutorial. Tell your friends! NOW!</description>
9. </entry>
10. </blog>

注解的使用方式,使用之前必须加上注解类才有作用:

1. XStream xstream = new XStream();
2. xstream.processAnnotations(Blog.class);
3. 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);

1. @XStreamAlias("blog")
2. public class Blog {
3. @XStreamAlias("author")
4. private Author writer;
5. .....
6. }

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:

1. xstream.useAttributeFor(Blog.class, "writer");
2. //重新命名
3. xstream.aliasField("author", Blog.class, "writer");
4. //注册转换器
5. 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

1. public AuthorConverter() {
2. }

b 类声明必须为:public

1. public class AuthorConverter implements SingleValueConverter {
2. ...
3. }

不用注解这二点都可以不强制要求! 
完整代码如下:

1. import com.thoughtworks.xstream.XStream;
2. import com.thoughtworks.xstream.annotations.XStreamAlias;
3. import com.thoughtworks.xstream.annotations.XStreamAsAttribute;
4. import com.thoughtworks.xstream.annotations.XStreamConverter;
5. import com.thoughtworks.xstream.annotations.XStreamImplicit;
6. @XStreamAlias("blog")
7. public class Blog {
8. @XStreamAsAttribute
9. @XStreamAlias("author")
10. @XStreamConverter(AuthorConverter.class)
11. private Author writer;
12. @XStreamImplicit
13. private List entries = new ArrayList();
14. public Blog(Author writer) {
15. this.writer = writer;
16. }
17. public void add(Entry entry) {
18. entries.add(entry);
19. }
20. public List getContent() {
21. return entries;
22. }
23. public static void main(String[] args) {
24. Blog teamBlog = new Blog(new Author("Guilherme Silveira"));
25. teamBlog.add(new Entry("first", "My first blog entry."));
26. teamBlog
27. .add(new Entry("tutorial",
28. "Today we have developed a nice alias tutorial. Tell your friends! NOW!"));
29. XStream xstream = new XStream();
30. xstream.processAnnotations(Blog.class);
31. xstream.processAnnotations(Entry.class);
32. // 重新命名节点名
33. // xstream.aliasPackage("", "xtream");
34. /*
35. * xstream.alias("blog", Blog.class); xstream.alias("entry",
36. * Entry.class); //重新命名属性名 // xstream.aliasField("author", Blog.class,
37. * "writer"); //去节点 xstream.addImplicitCollection(Blog.class,
38. * "entries"); // xstream.useAttributeFor(Blog.class, "writer"); //
39. * xstream.aliasField("author", Blog.class, "writer"); //
40. * xstream.addImplicitCollection(Blog.class, "entries");
41. * //使用这个属性名作为节点上的元素 xstream.useAttributeFor(Blog.class, "writer");
42. * //重新命名 xstream.aliasField("author", Blog.class, "writer"); //注册转换器
43. * xstream.registerConverter(new AuthorConverter());
44. */
45. System.out.println(xstream.toXML(teamBlog));
46. }
47. }