EJB3 and JPA step by step tutorial using Eclipse

Here I explain step by step how to create an EJB 3 with JPA application in Eclipse IDE.
This tutorial is for beginners who want to learn steps to create EJB persistence application with Eclipse and Jboss.

Tools used

Eclipse (Galileo)
Jboss-5.1.0.GA
MySQL database

First of all I'll create a database called studentmgt_db. You can use MySQL GUI tool like MySQL Query Browser or MySQL Work Bench to create a database.

Then I'm going to create a datasource. Go to your jboss directory  ..jboss-5.1.0.GA\docs\examples\jca inside that folder there is file called mysql-ds.xml. I copied that file to  ...jboss-5.1.0.GA\server\default\deploy. Then you can add your database details to that file.

mysql-ds.xml

<?xml version="1.0" encoding="UTF-8"?>

<!-- $Id: mysql-ds.xml 41017 2006-02-07 14:26:14Z acoliver $ -->
<!--  Datasource config for MySQL using 3.0.9 available from:
http://www.mysql.com/downloads/api-jdbc-stable.html
-->

<datasources>
  <local-tx-datasource>
    <jndi-name>StudentMgtDS</jndi-name>
    <connection-url>jdbc:mysql://localhost:3306/studentmgt_db</connection-url>
    <driver-class>com.mysql.jdbc.Driver</driver-class>
    <user-name>root</user-name>
    <password>123</password>
    <exception-sorter-class-name>org.jboss.resource.adapter.jdbc.vendor.MySQLExceptionSorter</exception-sorter-class-name>
    <!-- should only be used on drivers after 3.22.1 with "ping" support
    <valid-connection-checker-class-name>org.jboss.resource.adapter.jdbc.vendor.MySQLValidConnectionChecker</valid-connection-checker-class-name>
    -->
    <!-- sql to call when connection is created
    <new-connection-sql>some arbitrary sql</new-connection-sql>
      -->
    <!-- sql to call on an existing pooled connection when it is obtained from pool - MySQLValidConnectionChecker is preferred for newer drivers
    <check-valid-connection-sql>some arbitrary sql</check-valid-connection-sql>
      -->

    <!-- corresponding type-mapping in the standardjbosscmp-jdbc.xml (optional) -->
    <metadata>
       <type-mapping>mySQL</type-mapping>
    </metadata>
  </local-tx-datasource>
</datasources>

 Now create EJB project.

Create a new EJB project called StudentManagementEJB. I use JBoss server as application server.

Create a xml file called persistence.xml in META-INF directory.

persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0"
 xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
 <persistence-unit name="StudentMgtPU"
  transaction-type="JTA">
  <jta-data-source>java:/StudentMgtDS</jta-data-source>
  <properties>
   <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
   <property name="hibernate.hbm2ddl.auto" value="create" />
  </properties>
 </persistence-unit>
</persistence>

Then we have to create an Entity class. Right click on the project -> New -> Class

•  Entity Class must have @Entity annotaion
•  Must have a public or protected no-arg constructor
•  If it passed as a detached object through a remote interface, Must implement Serializable
•  Must have an id annotated with @Id

I created a entity class called Student.java
 

Student.java

package com.sameera.domain;

import java.io.Serializable;
import javax.persistence.*;

@Entity
@Table(name = "student")
public class Student implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue
    @Column(name = "id")
    private Integer id;
    @Column(name = "first_name", length = 100)
    private String firstName;
    @Column(name = "last_name", length = 100)
    private String lastName;
    @Column(name = "email", length = 100)
    private String email;

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getFirstName() {
        return firstName;
    }

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

    public Integer getId() {
        return id;
    }

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

    public String getLastName() {
        return lastName;
    }

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

Create session beans.

I create a Stateless session bean with Local interface.

I added business methods and added add student code.

ManageStudentSessionBeanLocal.java

package com.sameera.session;

import javax.ejb.Local;

import com.sameera.domain.Student;

/**
 * 
 * @author Sameera Jayasekara
 * 
 */
@Local
public interface ManageStudentSessionBeanLocal {
 public boolean addStudent(Student Student);
}

ManageStudentSessionBean.java

package com.sameera.session;

import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

import com.sameera.domain.Student;

/**
 * Session Bean implementation class ManageStudentSessionBean
 * 
 * @author Sameera Jayasekara
 */
@Stateless
public class ManageStudentSessionBean implements ManageStudentSessionBeanLocal {

 @PersistenceContext
 private EntityManager entityManager;

 @Override
 public boolean addStudent(Student student) {
  entityManager.persist(student);
  return true;
 }

}

Run EJB application on Jboss server.

See the server console JNDI bindings.

 Now see the database. Student table is created.

Now start working on web application.
File -> New -> Dynamic Web Project

Go next Select 'Generate web.xml deployment descriptor' and finish.

Right click on web content and create a new jsp called index.jsp.

index.jsp

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
    "http://www.w3.org/TR/html4/loose.dtd">

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>EJB3 JPA Jboss - codesstore.blogspot.com</title>
    </head>
    <body>

        <form action="ManageStudentServlet" method="POST">

            <table border="0" width="100%">
                <tr>
                    <td colspan="3">  ${message}</td>
                </tr>
                <tr>
                    <td>First Name</td>
                    <td>:</td>
                    <td><input type="text" name="fname" value="" /></td>
                </tr>
                <tr>
                    <td>Last Name</td>
                    <td>:</td>
                    <td><input type="text" name="lname" value="" /></td>
                </tr>
                <tr>
                    <td>Email</td>
                    <td>:</td>
                    <td><input type="text" name="email" value="" /></td>
                </tr>
                <tr>
                    <td></td>
                    <td></td>
                    <td><input type="submit" value="Add" name="Add" /></td>
                </tr>
            </table>

        </form>

    </body>
</html>

Create  a servlet to handle the request.
File -> New -> Servlet

Before calling Enterprise beans we have to add the ejb project to build path.

 Go to projects tab and add StudentManagementEJB project.

ManageStudentServlet.java

package com.sameera.controller;

import java.io.IOException;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.sameera.domain.Student;
import com.sameera.session.ManageStudentSessionBeanLocal;

/**
 * 
 * @author Sameera Jayasekara
 * 
 */
public class ManageStudentServlet extends HttpServlet {

 private static final long serialVersionUID = 1L;
 private ManageStudentSessionBeanLocal manageStudentSessionBeanLocal;

 public void init(ServletConfig config) throws ServletException {

  super.init(config);
  try {

   Context context = new InitialContext();
   manageStudentSessionBeanLocal = (ManageStudentSessionBeanLocal) context
     .lookup("ManageStudentSessionBean/local");

  } catch (NamingException e) {
   e.printStackTrace();
  }

 }

 protected void doGet(HttpServletRequest request,
   HttpServletResponse response) throws ServletException, IOException {

 }

 protected void doPost(HttpServletRequest request,
   HttpServletResponse response) throws ServletException, IOException {

  String message = "";

  String firstName = request.getParameter("fname");
  String lastName = request.getParameter("lname");
  String email = request.getParameter("email");

  Student student = new Student();
  student.setFirstName(firstName);
  student.setLastName(lastName);
  student.setEmail(email);

  if (manageStudentSessionBeanLocal.addStudent(student)) {
   message = "Student Successfuly Added";
  } else {
   message = "Student Adding Failed";
  }

  request.setAttribute("message", message);
  RequestDispatcher rd = request.getRequestDispatcher("index.jsp");
  rd.forward(request, response);

 }

}

I looked up ManageStudentSessionBean/local. You can see server console to find JNDI bindings(see image given above)

You can use @EJB annotaions to dependancy injection in a servlet but I tried it with JBoss that didn't work.Then I used @EJB(mappedName="Test"), @EJB with mappedName attribute( @Stateless(mappedName="Test") also used).Then it worked with remote interface. But I prefer JNDI lookup.

web.xml configuration file looks like this.

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>StudentManagementWeb</display-name>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
    <description></description>
    <display-name>ManageStudentServlet</display-name>
    <servlet-name>ManageStudentServlet</servlet-name>
    <servlet-class>com.sameera.controller.ManageStudentServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>ManageStudentServlet</servlet-name>
    <url-pattern>/ManageStudentServlet</url-pattern>
  </servlet-mapping>
</web-app>

Now You can run the web application.

 Check the database data will be added.

Project structure in Eclipse

Note : I put mysql-connector-java-5.1.5-bin.jar to ...jboss-5.1.0.GA\server\default\lib