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
);