<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration
  PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN"
  "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
<session-factory>
   <property name="hibernate.connection.url">
      jdbc:postgresql://localhost/newgenlib
   </property>
   <property name="hibernate.connection.driver_class">
      org.postgresql.Driver
   </property>
   <property name="hibernate.connection.username">
      postgres
   </property>
   <property name="hibernate.connection.password">
      girish
   </property>
   <property name="hibernate.connection.pool_size">
      0
   </property>
   <!--<property name="hibernate.jdbc.batch_size">0</property>-->
   <property name="hibernate.dialect">
      org.hibernate.dialect.PostgreSQLDialect
   </property>
   <property name="hibernate.show_sql">
      true
   </property>
   <property name="connection.autocommit">
      false
   </property>
<!-- "Import" the mapping resources here -->
<mapping resource="InsertBean.hbm.xml"/>
</session-factory>
</hibernate-configuration>

mapping xml

Insertbean.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
  <class name="InsertBean" table="InsertBean">
     <id column="docid" unsaved-value="-1" type="integer">
       <generator class="sequence">
         <param name="sequence">sequence_id</param>
      </generator>
     </id>
     <property name="First" column="first" type="string"/>
    <property name="Middle" column="middle" type="string"/>
    <property name="Last" column="last" type="string"/>
   </class>
</hibernate-mapping>



my pojo class is given below


public class InsertBean
{
   public String First;
   public String Middle;
   public String Last;
   public InsertBean()
   {
      
   }
   public InsertBean(String First,String Middle,String Last)
   {
      this.First=First;
      this.Middle=Middle;
      this.Last=Last;
   }

   public String getFirst()
   {
      return this.First;
   }
   public void setFirst(String First)
   {
      this.First=First;
   }
   public String getMiddle()
   {
      return this.Middle;
   }
   public void setMiddle(String Middle)
   {
         this.Middle=Middle;
   }
   public String getLast()
   {
      return this.Last;
   }
      public void setLast(String Last)
   {
      this.Last= Last;
   }

}

MyServlet

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class MyServlet extends HttpServlet
{
   public void doGet(HttpServletRequest req,HttpServletResponse res) throws ServletException,IOException
   {
       
       System.out.println("INSIDE SERVLET");
       HibernateInsert hi=new HibernateInsert();
       hi.insert();
   
   
   }

}


HibernateInsert.java

import java.util.Date;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
public class HibernateInsert
{
   public void insert(){
      
         SessionFactory factory =
      new Configuration().configure().buildSessionFactory();
      Session session = factory.openSession();
      session.beginTransaction();
      InsertBean m1 = new InsertBean();
      m1.setFirst("new");
      m1.setMiddle("gen");
      m1.setLast("lib");
      session.save(m1);
      session.getTransaction().commit();
      session.close();
      }
      

}

public class InsertBean {
    private int docid;
   
    //these should normally be private
    public String First;
    public String Middle;
    public String Last;
...

   <class name="data.User" table="USERS">
      <id name="id" type="int" column="ID">
         <generator class="native" />
      </id>