Interceptor trong Hibernate

import java.io.Serializable;
import java.util.Iterator;

import org.hibernate.EmptyInterceptor;
import org.hibernate.type.Type;

import hibernate.interceptor.entity.Employee;

public class MyInterceptor extends EmptyInterceptor {

	public void onDelete(Object entity, Serializable id, Object[] state, String[] propertyNames, Type[] types) {
		// do nothing
	}

	// This method is called when Employee object gets updated.
	public boolean onFlushDirty(Object entity, Serializable id, Object[] currentState, Object[] previousState,
			String[] propertyNames, Type[] types) {
		if (entity instanceof Employee) {
			System.out.println("Update Operation");
			return true;
		}
		return false;
	}

	public boolean onLoad(Object entity, Serializable id, Object[] state, String[] propertyNames, Type[] types) {
		// do nothing
		return true;
	}

	// This method is called when Employee object gets created.
	public boolean onSave(Object entity, Serializable id, Object[] state, String[] propertyNames, Type[] types) {
		if (entity instanceof Employee) {
			System.out.println("Create Operation");
			return true;
		}
		return false;
	}

	// called before commit into database
	public void preFlush(Iterator iterator) {
		System.out.println("preFlush");
	}

	// called after committed into database
	public void postFlush(Iterator iterator) {
		System.out.println("postFlush");
	}
}

package hibernate.interceptor.entity;

public class Employee {
	private int id;
	private String firstName;
	private String lastName;
	private int salary;

	public Employee() {
	}

	public Employee(String fname, String lname, int salary) {
		this.firstName = fname;
		this.lastName = lname;
		this.salary = salary;
	}

	public int getId() {
		return id;
	}

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

	public String getFirstName() {
		return firstName;
	}

	public void setFirstName(String first_name) {
		this.firstName = first_name;
	}

	public String getLastName() {
		return lastName;
	}

	public void setLastName(String last_name) {
		this.lastName = last_name;
	}

	public int getSalary() {
		return salary;
	}

	public void setSalary(int salary) {
		this.salary = salary;
	}
}

create table EMPLOYEE (
   id INT NOT NULL auto_increment,
   first_name VARCHAR(20) default NULL,
   last_name  VARCHAR(20) default NULL,
   salary     INT  default NULL,
   PRIMARY KEY (id)
);

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
 "-//Hibernate/Hibernate Mapping DTD//EN"
 "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> 

<hibernate-mapping>
   <class name="hibernate.interceptor.entity.Employee" table="EMPLOYEE">
      <meta attribute="class-description">
         Lớp này chứa chi tiết về employee
      </meta>
      <id name="id" type="int" column="id">
         <generator class="native"/>
      </id>
      <property name="firstName" column="first_name" type="string"/>
      <property name="lastName" column="last_name" type="string"/>
      <property name="salary" column="salary" type="int"/>
   </class>
</hibernate-mapping>

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration SYSTEM 
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
	<session-factory>
		<property name="hibernate.dialect">
			org.hibernate.dialect.MySQLDialect
		</property>
		<property name="hibernate.connection.driver_class">
			com.mysql.jdbc.Driver
		</property>

		 
		<property name="hibernate.connection.url">
			jdbc:mysql://localhost/testdb
		</property>
		<property name="hibernate.connection.username">
			root
		</property>
		<property name="hibernate.connection.password">
			1234567890
		</property>

		 
		<mapping resource="Employee.hbm.xml" />

	</session-factory>
</hibernate-configuration>

import java.util.Iterator;
import java.util.List;

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

import hibernate.interceptor.entity.Employee;

public class ManageEmployee {
	private static SessionFactory factory;

	public static void main(String[] args) {
		try {
			factory = new Configuration().configure().buildSessionFactory();
		} catch (Throwable ex) {
			System.err.println("Failed to create sessionFactory object." + ex);
			throw new ExceptionInInitializerError(ex);
		}

		ManageEmployee ME = new ManageEmployee();

		// Add few employee records in database
		Integer empID1 = ME.addEmployee("Zara", "Ali", 1000);
		Integer empID2 = ME.addEmployee("Daisy", "Das", 5000);
		Integer empID3 = ME.addEmployee("John", "Paul", 10000);

		// List down all the employees
		ME.listEmployees();

		// Update employee's records
		ME.updateEmployee(empID1, 5000);

		// Delete an employee from the database
		ME.deleteEmployee(empID2);

		// List down new list of the employees
		ME.listEmployees();
	}

	// Method to CREATE an employee in the database
	public Integer addEmployee(String fname, String lname, int salary) {
		Session session = factory.openSession(new MyInterceptor());
		Transaction tx = null;
		Integer employeeID = null;
		try {
			tx = session.beginTransaction();
			Employee employee = new Employee(fname, lname, salary);
			employeeID = (Integer) session.save(employee);
			tx.commit();
		} catch (HibernateException e) {
			if (tx != null)
				tx.rollback();
			e.printStackTrace();
		} finally {
			session.close();
		}
		return employeeID;
	}

	// Method to READ all the employees
	public void listEmployees() {
		Session session = factory.openSession(new MyInterceptor());
		Transaction tx = null;
		try {
			tx = session.beginTransaction();
			List employees = session.createQuery("FROM Employee").list();
			for (Iterator iterator = employees.iterator(); iterator.hasNext();) {
				Employee employee = (Employee) iterator.next();
				System.out.print("First Name: " + employee.getFirstName());
				System.out.print("  Last Name: " + employee.getLastName());
				System.out.println("  Salary: " + employee.getSalary());
			}
			tx.commit();
		} catch (HibernateException e) {
			if (tx != null)
				tx.rollback();
			e.printStackTrace();
		} finally {
			session.close();
		}
	}

	// Method to UPDATE salary for an employee
	public void updateEmployee(Integer EmployeeID, int salary) {
		Session session = factory.openSession(new MyInterceptor());
		Transaction tx = null;
		try {
			tx = session.beginTransaction();
			Employee employee = (Employee) session.get(Employee.class, EmployeeID);
			employee.setSalary(salary);
			session.update(employee);
			tx.commit();
		} catch (HibernateException e) {
			if (tx != null)
				tx.rollback();
			e.printStackTrace();
		} finally {
			session.close();
		}
	}

	// Method to DELETE an employee from the records
	public void deleteEmployee(Integer EmployeeID) {
		Session session = factory.openSession(new MyInterceptor());
		Transaction tx = null;
		try {
			tx = session.beginTransaction();
			Employee employee = (Employee) session.get(Employee.class, EmployeeID);
			session.delete(employee);
			tx.commit();
		} catch (HibernateException e) {
			if (tx != null)
				tx.rollback();
			e.printStackTrace();
		} finally {
			session.close();
		}
	}
}