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XStream注释

XStream支持注释做同样的任务,正如我们在前面的章节中是自动配置,而不是代码1所做的。在前面的章节中,我们已经看到了下面的代码配置。
xstream.alias("student", Student.class);
xstream.alias("note", Note.class);
xstream.useAttributeFor(Student.class, "studentName");
xstream.aliasField("name", Student.class, "studentName");
xstream.addImplicitCollection(Student.class, "notes");
下面的代码片段来说明使用annoations更容易的方式做同样的工作。
@XStreamAlias("student") //define class level alias
class Student {
 
 
 @XStreamAlias("name") //define field level alias
 @XStreamAsAttribute //define field as attribute
 private String studentName;
 
 @XStreamImplicit //define list as an implicit collection
 private List<Note> notes = new ArrayList<Note>();
 
 @XStreamOmitField //omit a field to not to be a part of XML
 private int type;
}
让我们使用XStream测试上面的注释。 创建一个Java类名为XStreamTester文件在 C:\>XStream_WORKSPACE\com\yiibai\xstream. File: XStreamTester.java
package cn.sxt.xstream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.util.ArrayList;
import java.util.List;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.sax.SAXSource;
import javax.xml.transform.sax.SAXTransformerFactory;
import javax.xml.transform.stream.StreamResult;
import org.xml.sax.InputSource;
import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.annotations.XStreamAlias;
import com.thoughtworks.xstream.annotations.XStreamAsAttribute;
import com.thoughtworks.xstream.annotations.XStreamImplicit;
import com.thoughtworks.xstream.annotations.XStreamOmitField;
import com.thoughtworks.xstream.io.xml.StaxDriver;
public class XStreamTester {
   public static void main(String args[]){
      XStreamTester tester = new XStreamTester();
      XStream xstream = new XStream(new StaxDriver());
      Student student = tester.getStudentDetails();
      xstream.processAnnotations(Student.class);
      //Object to XML Conversion
      String xml = xstream.toXML(student);
      System.out.println(formatXml(xml));
   }
   private Student getStudentDetails(){
      Student student = new Student("Mahesh");
      student.addNote(new Note("first","My first assignment."));
      student.addNote(new Note("second","My Second assignment."));
  student.setType(1);
      return student;
   }
   public static String formatXml(String xml){
      try{
         Transformer serializer= SAXTransformerFactory.newInstance().newTransformer();
         serializer.setOutputProperty(OutputKeys.INDENT, "yes");
         serializer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
         Source xmlSource=new SAXSource(new InputSource(new ByteArrayInputStream(xml.getBytes())));
         StreamResult res =  new StreamResult(new ByteArrayOutputStream());            
         serializer.transform(xmlSource, res);
         return new String(((ByteArrayOutputStream)res.getOutputStream()).toByteArray());
      }catch(Exception e){
         return xml;
      }
   }
}
@XStreamAlias("student")
class Student {
   @XStreamAlias("name")
   @XStreamAsAttribute
   private String studentName;
   @XStreamImplicit
   private List<Note> notes = new ArrayList<Note>();
   public Student(String name) {
      this.studentName = name;
   }
   public void addNote(Note note) {
      notes.add(note);
   }
   public String getName(){
      return studentName;
   }
   public List<Note> getNotes(){
      return notes;
   }
   
   @XStreamOmitField
   private int type;
   public int getType(){
      return type;
   }
   public void setType(int type){
      this.type = type;
   }
}
@XStreamAlias("note")
class Note {
   private String title;
   private String description;
   public Note(String title, String description) {
      this.title = title;
      this.description = description;
   }
   public String getTitle(){
      return title;
   }
   public String getDescription(){
      return description;
   }     
}
验证结果 使用javac编译器编译如下类:
C:\XStream_WORKSPACE\cn\sxt\xstream>javac XStreamTester.java
现在运行XStreamTester看到的结果:
C:\XStream_WORKSPACE\cn\sxt\xstream>java XStreamTester
验证结果
<?xml version="1.0" encoding="UTF-8"?>
<student name="Mahesh">
  <note>
    <title>first</title>
    <description>My first assignment.</description>
  </note>
  <note>
    <title>second</title>
    <description>My Second assignment.</description>
  </note>
</student>
为了告诉XStream框架来处理注释,需要XML序列化之前添加下面的命令。
xstream.processAnnotations(Student.class);
或者
xstream.autodetectAnnotations(true);
正文到此结束
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