Hibernate – Annotations

<dependencies>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>3.6.3.Final</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-annotations</artifactId>
        <version>3.5.6-Final</version>
    </dependency>
    <dependency>
        <groupId>javassist</groupId>
        <artifactId>javassist</artifactId>
        <version>3.12.1.GA</version>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.6</version>
    </dependency>
</dependencies>

create table testdb.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)
);

import javax.persistence.*;

@Entity
@Table(name = "EMPLOYEE")
public class Employee {
   @Id @GeneratedValue
   @Column(name = "id")
   private int id;

   @Column(name = "first_name")
   private String firstName;

   @Column(name = "last_name")
   private String lastName;

   @Column(name = "salary")
   private int salary;  

   public Employee() {}
   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;
   }
}

<?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>
    </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.AnnotationConfiguration;

import vn.viettuts.hibernate.annotation.entity.Employee;

public class ManageEmployee {
    private static SessionFactory factory; 
    public static void main(String[] args) {
       try{
          factory = new AnnotationConfiguration().
                    configure().
                    //addPackage("com.xyz") //add package if used.
                    addAnnotatedClass(Employee.class).
                    buildSessionFactory();
       }catch (Throwable ex) { 
          ex.printStackTrace();
          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();
       Transaction tx = null;
       Integer employeeID = null;
       try{
          tx = session.beginTransaction();
          Employee employee = new Employee();
          employee.setFirstName(fname);
          employee.setLastName(lname);
          employee.setSalary(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();
       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();
       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();
       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(); 
       }
    }
 }