Javax.xml.bind.Binder.getEventHandler() Method

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Description

The Javax.xml.bind.Binder.getEventHandler() method returns the current event handler or the default event handler if one hasn't been set.

Declaration

Following is the declaration for javax.xml.bind.Binder.getEventHandler() method

public abstract ValidationEventHandler getEventHandler()

Parameters

NA

Return Value

This method returns the current ValidationEventHandler or the default event handler if it hasn't been set.

Exception

JAXBException − if an error was encountered while getting the current event handler.

Example

The following example shows the usage of javax.xml.bind.Binder.getEventHandler() method. To proceed, consider the following Student class which will be used to have objects for marshalling purpose −

package com.tutorialspoint;

import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
 
@XmlRootElement
public class Student{
 
   String name;
   int age;
   int id;

   public String getName(){
      return name;
   }

   @XmlElement
   public void setName(String name){
      this.name = name;
   }

   public int getAge(){
      return age;
   }

   @XmlElement
   public void setAge(int age){
      this.age = age;
   }

   public int getId(){
      return id;
   }

   @XmlAttribute
   public void setId(int id){
      this.id = id;
   }
}

Now let us create main class which will be used to unmarshal ie. convert Student.xml into an Student object. This example unmarshals the Student.xml file and prints it at STDOUT.

package com.tutorialspoint;

import java.io.File;

import javax.xml.XMLConstants;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Binder;
import javax.xml.bind.ValidationEventHandler;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.validation.Schema;
import javax.xml.validation.SchemaFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Node;

public class BinderDemo {
   public static void main(String[] args) {
      
  
      try {
         // we need a blank document to store final xml output
         DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
         DocumentBuilder docBuilder = dbf.newDocumentBuilder();
         Document document = docBuilder.parse("Student.xml");
          
         // xml constant
         String schemaLanguage = XMLConstants.W3C_XML_SCHEMA_NS_URI;
         SchemaFactory sf = SchemaFactory.newInstance(schemaLanguage);
         File f = new File("Student.xsd");
         
         // create new schema
         Schema schema = sf.newSchema(f);
         
         // create JAXBContext which will be used to create a Binder
         JAXBContext jc = JAXBContext.newInstance(Student.class);

         // create binder object
         Binder<Node> binder = jc.createBinder();

         // set the property
         binder.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
         
         // get xml node
         Node xmlNode = document.getDocumentElement();
         
         // set schema for binder
         binder.setSchema(schema);
         
         // set validation event handler
         binder.setEventHandler(new StudentValidationEventHandler());
         
         ValidationEventHandler veh = binder.getEventHandler();
         
         System.out.println("Class : "+veh.getClass().getName());
         
         // unmarshaling xml to JAXB object 
         Student st = (Student)binder.unmarshal(xmlNode);
         
         // finally print the marshalled object on stdout
         System.out.println("Name : "+st.getName());
         System.out.println("Age : "+st.getAge());
  
      }catch(Exception ex) {
         ex.printStackTrace();
      }
   }
}

StudentValidationEventHandler class is created to set new event handler to the binder class.

package com.tutorialspoint;

import javax.xml.bind.ValidationEvent;
import javax.xml.bind.ValidationEventHandler;

public class StudentValidationEventHandler implements ValidationEventHandler {
   public boolean handleEvent(ValidationEvent event) {
      System.out.println("\nEvent");
      System.out.println("Severity:  " + event.getSeverity());
      System.out.println("Message:  " + event.getMessage());
      System.out.println("Linked Exception:  " + event.getLinkedException());
      System.out.println("LOCATOR");
      System.out.println("   Line Number:  " + event.getLocator().getLineNumber());
      System.out.println("   Column Number:  " + event.getLocator().getColumnNumber());
      System.out.println("   Offset:  " + event.getLocator().getOffset());
      System.out.println("   Object:  " + event.getLocator().getObject());
      System.out.println("   Node:  " + event.getLocator().getNode());
      System.out.println("   Url:  " + event.getLocator().getURL());
      return true;
   }
}

The Student.xml is used for unmarshalling. Below are the content details of the file −

<?xml version = "1.0" encoding = "UTF-8" standalone = "yes"?>
<student id = "10">
   <age>12</age>
   <name>Malik</name>
</student>

The following Student.xsd is implemented in the program to set schema in the binder object.

<?xml version = "1.0" encoding = "utf-8"?>
<xs:schema attributeFormDefault = "unqualified" 
   elementFormDefault = "qualified" xmlns:xs = "http://www.w3.org/2001/XMLSchema">
   <xs:element name = "student">
      <xs:complexType>
         <xs:sequence>
            <xs:element name = "age" type = "xs:unsignedByte" />
            <xs:element name = "name" type = "xs:string" />
         </xs:sequence>
         <xs:attribute name = "id" type = "xs:unsignedByte" use = "required" />
      </xs:complexType>
   </xs:element>
</xs:schema>

Before we proceed for compilation, we need to make sure that that we download JAXB2.xxx.jar and put it in our CLASSPATH. Once setup is ready, let us compile and run the above program, this will produce the following result −

Class : com.tutorialspoint.StudentValidationEventHandler
Name : Malik
Age : 12