Converting JAVA Objects to XML and Vice Versa

JAXB, stands for Java Architecture for XML Binding, using JAXB annotation to convert Java object to / from XML file. In this tutorial, we show you how to use JAXB to do following stuffs :

1. Marshalling – Convert a Java object into a XML file.
2. Unmarshalling – Convert XML content into a Java Object.

Technologies used in this article

1. JDK 1.6
2. JAXB 2.0

Working with JAXB is easy, just annotate object with JAXB annotation, later use jaxbMarshaller.marshal() orjaxbMarshaller.unmarshal() to do the object / XML conversion.

1. JAXB Dependency

No extra jaxb libraries are required if you are using JDK1.6 or above, because JAXB is bundled in JDK 1.6.

Note
For JDK < 1.6, download JAXB from here, and puts “jaxb-api.jar” and “jaxb-impl.jar” on your project classpath.

2. JAXB Annotation

For object that need to convert to / from XML file, it have to annotate with JAXB annotation. The annotation are pretty self-explanatory, you can refer to this JAXB guide for detail explanation.

 import javax.xml.bind.annotation.XmlAttribute;  
 import javax.xml.bind.annotation.XmlRootElement;  
 /**  
  * A message.  
  */  
 @XmlRootElement  
 public class Message {  
   /**  
   * The sender.  
   */  
   private String from;  
   /**  
   * The receiver.  
   */  
   private String to;  
   /**  
   * A unique identification.  
   */  
   private int id;  
   /**  
   * The actual message.  
   */  
   private String text;  
   /**  
   * Default contstructor.  
   */  
   public Message() {  
   }  
   public String getFrom() {  
    return from;  
   }  
   public void setFrom(String from) {  
    this.from = from;  
   }  
   public String getTo() {  
    return to;  
   }  
   public void setTo(String to) {  
    this.to = to;  
   }  
   public String getText() {  
    return text;  
   }  
   public void setText(String text) {  
    this.text = text;  
   }  
   public int getId() {  
    return id;  
   }  
   @XmlAttribute  
   public void setId(int id) {  
    this.id = id;  
   }  
   public String toString() {  
    return String.format("Message[id=%s, from=%s, to=%s, text=%s]", id, from, to, text);  
   }  
 }  

3. Convert Object to XML

JAXB marshalling example, convert customer object into a XML file. The jaxbMarshaller.marshal() contains a lot of overloaded methods, find one that suit your output.

 import java.io.File;  
 import javax.xml.bind.JAXBContext;  
 import javax.xml.bind.JAXBException;  
 import javax.xml.bind.Marshaller;  
 public class MessageImpl {  
      public static void main(String[] args) throws JAXBException{  
           Message message = new Message();  
           message.setFrom("Konda Reddy");  
           message.setTo("Prasad Reddy");  
           message.setText("Hello from JAXB!");  
           message.setId(123);  
           // Create a JAXB context and a marshaller  
           JAXBContext context = JAXBContext.newInstance(Message.class);  
           Marshaller handler = context.createMarshaller();  
           // Set the output in pretty format  
           handler.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);  
           // Make the actual serialization  
           handler.marshal(message, new File("src/output.xml"));  
           // Here I am using eclipse project for that src/output.xml  
      }  
 }  

Output

 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>  
 <message id="123">  
   <from>Konda Reddy</from>  
   <text>Hello from JAXB!</text>  
   <to>Prasad Reddy</to>  
 </message>  

4. Convert XML to Object

JAXB unmarshalling example, convert a XML file content into a customer object. ThejaxbMarshaller.unmarshal() contains a lot of overloaded methods, find one that suit yours.

 import java.io.File;  
 import javax.xml.bind.JAXBContext;  
 import javax.xml.bind.Unmarshaller;  
 public class XmlToObject {  
      public static void main(String [] args){  
      try{// Create a JAXB context and an unmarshaller  
      JAXBContext context = JAXBContext.newInstance(Message.class);  
      Unmarshaller handler = context.createUnmarshaller();  
      // Get the object  
      Message msg = (Message)handler.unmarshal(new File("src/output.xml"));  
      System.out.println(msg);  
      System.out.println(msg.getId());  
      System.out.println(msg.getText());  
      System.out.println(msg.getFrom());  
      System.out.println(msg.getTo());  
      System.out.println(msg.getClass().getName());  
      }catch(Exception e){  
           e.printStackTrace();  
      }  
      }  
 }  

Output

 Message[id=123, from=Konda Reddy, to=Prasad Reddy, text=Hello from JAXB!]  
 123  
 Hello from JAXB!  
 Konda Reddy  
 Prasad Reddy  
 Message  

Enjoy with this is example