Hi,

The Java Persistence Architecture API (JPA) is a Java specification for accessing, persisting, and managing data between Java objects / classes and a relational database. JPA was defined as part of the EJB 3.0 specification as a replacement for the EJB 2 CMP Entity Beans specification. JPA is now considered the standard industry approach for Object to Relational Mapping (ORM) in the Java Industry.

The JBoss Application Server JPA subsystem implements the JPA 2.0 container-managed requirements. JPA Applications use the Hibernate (core) 4.0 persistence provider, that is included with JBoss AS. Hibernate 4 is packaged with the AS and is the default persistence provider. The JPA 2.0 Specifications can be found in the following link: http://jcp.org/aboutJava/communityprocess/pfd/jsr317/index.html

A Best reference for JPA features inside JBoss AS7 can be foun in the following link: https://docs.jboss.org/author/display/AS7/JPA+Reference+Guide

However in this current emo we will just create a Simple JPA persistence unit and then we will try to insert some employee detils insie the DataBase. So basically this is just as a startup.

In this example we will mainly focus on following points

Point-1). For Web Applications we should put the “persistence.xml” file inside “${WEB_APPLICATION}/WEB-INF/classes/META-INF/persistence.xml”
For EJB Applications we should put the “persistence.xml” file inside “${EJB_JAR}/META-INF”

Point-2). To inject the EntityManager inside our Web Components we can use the annotation @javax.persistence.PersistenceContext(unitName=”name”)

Point-3). We can use the @javax.ejb.EJB annotation to inject an Enterprise Java Bean inside our app components. Like @EJB(lookup=”jndiName”)

Server Side Configuration

Point-1). Here we are using JBoss AS7 latest build “jboss-as-7.1.0.Beta1” which can be downloaded from the following link: http://www.jboss.org/jbossas/downloads

Point-2). In order to get more details on how to create MySQL DataSource in JBoss AS7 you can refer to the following article: http://middlewaremagic.com/jboss/?p=872
Create a DataSource inside “${JBOSS_HOME}/standalone/configuration/standalone-full.xml” file as following:

        <subsystem xmlns="urn:jboss:domain:datasources:1.0">
            <datasources>
                <datasource jndi-name="java:jboss/datasources/ExampleDS" pool-name="H2DS" enabled="true">
                    <connection-url>
                        jdbc:h2:mem:test;DB_CLOSE_DELAY=-1
                    </connection-url>
                    <driver>
                        h2
                    </driver>
                    <security>
                        <security-domain>
                            encrypted-ds
                        </security-domain>
                    </security>
                </datasource>


                <!-- Below is the DataSource Configuration which we added for our JPA TestCase-->
                <datasource jndi-name="java:/MySqlDS" pool-name="MySqlDS_Pool" enabled="true" jta="false" use-ccm="false">
                    <connection-url>
                        jdbc:mysql://localhost:3306/testDB
                    </connection-url>
                    <driver-class>
                        com.mysql.jdbc.Driver
                    </driver-class>
                    <driver>
                        mysql-connector-java-5.1.13-bin.jar
                    </driver>
                    <security>
                        <user-name>someDBUserName</user-name>
                        <password>someDBPassword</password>
                    </security>
                </datasource>
                <!-- Above is the DataSource we created on MySQL Database -->


                <drivers>
                    <driver name="h2" module="com.h2database.h2">
                        <xa-datasource-class>
                            org.h2.jdbcx.JdbcDataSource
                        </xa-datasource-class>
                    </driver>
                </drivers>
            </datasources>
        </subsystem>

Point-3). Restart your JBoss AS7 from inside “/home/userone/jboss-as-7.1.0.Beta1/bin” directory as following:

.
 ./standalone.sh -c standalone-full.xml
.

Developing JPA Test Case

Step1). Create a directory somewhere in your filesystem like “/home/userone/JPA_1_On_AS7” where we will place our application build related stuff. Then create another directory “src” inside “/home/userone/JPA_1_On_AS7” where we will be placing our source codes and JSPs.

Step2). Now first of all we will create an Entity “Employee.java” as following inside the “/home/userone/JPA_1_On_AS7/src” directory.

package jpa;
import java.io.Serializable;
import javax.persistence.*;
import java.math.BigDecimal;

@Entity
@Table(name="Employee")
public class Employee implements Serializable {
	private static final long serialVersionUID = 1L;

	@Id
	private BigDecimal empno;

	private String ename;

    public Employee() {
    	System.out.println("Employee Object Created.");
    }

	public BigDecimal getEmpno() {
		return this.empno;
	}

	public void setEmpno(BigDecimal empno) {
		this.empno = empno;
	}

	public String getEname() {
		return this.ename;
	}

	public void setEname(String ename) {
		this.ename = ename;
	}
}

Step3). Now we will create a Simple Stateless SessionBean remote Interface “EmployeeServiceRemote.java” inside “/home/userone/JPA_1_On_AS7/src” directory as following:

package jpa;
import java.math.BigDecimal;
import java.util.Collection;
import javax.ejb.Remote;
@Remote

public interface EmployeeServiceRemote{
  public void doAction();
  public Employee createEmployee(BigDecimal id, String name);
  public void removeEmployee(BigDecimal id);
  public Employee findEmployee(BigDecimal id);
  public Collection<Employee> findAllEmployees() ;

}

Step4). Now we will Stateless Session Bean class “EmployeeService.java” by implementing the interface “EmployeeServiceRemote.java”. Place this file as well inside the “/home/userone/JPA_1_On_AS7/src” directory as following:

package jpa;
import java.math.BigDecimal;
import java.util.Collection;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;

@Stateless
public class EmployeeService implements EmployeeServiceRemote {
  @PersistenceContext(unitName="EmployeeService")
  EntityManager em;

  public EmployeeService() {
     System.out.println("nt Employee Object Created.");
  }

  public Employee createEmployee(BigDecimal id, String name) {
    Employee emp = new Employee();
    emp.setEmpno(id);
    emp.setEname(name);
    em.persist(emp);
    emp = findEmployee(id);
    System.out.println("nt Inside createEmployee() findEmployee result: "+emp);
    em.flush();
    return emp;
  }

  public void removeEmployee(BigDecimal id) {
       System.out.println("nt Inside removeEmployee("+id+")");
       Employee emp = findEmployee(id);
       if (emp != null) {
          em.remove(emp);
       }
  }

  public Employee findEmployee(BigDecimal id) {
        System.out.println("nt Inside findEmployee("+id+")");
        return em.find(Employee.class, id);
  }

  @SuppressWarnings("unchecked")
  public Collection<Employee> findAllEmployees() {
        System.out.println("nt Inside findAllEmployees()");
        Query query = em.createQuery("SELECT e FROM Employee e");
        return (Collection<Employee>) query.getResultList();
  }

  public void doAction(){
  }
}

Step5). Now we will write the “persistence.xml” file inside the “/home/userone/JPA_1_On_AS7/src” directory as following:

<?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="EmployeeService"> <!-- transaction-type="JTA" -->
		<jta-data-source>java:/MySqlDS</jta-data-source>
		<class>jpa.Employee</class>
		<properties>
			<property name="hibernate.hbm2ddl.auto" value="create-drop" />
                        <property name="hibernate.show_sql" value="true" />
			<property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
		</properties>
	</persistence-unit>
</persistence>

NOTE: We need to make sure that this “persistence.xml” file goes inside the “${war.name}/WEB-INF/classes/META-INF” directory of our WAR file.
Due to the property “hibernate.hbm2ddl.auto” the Employee table will be automatically created in the database as soon as we deploy the application on JBoss and will be automatically droped as soon as we undeploy our application. Valid values for this property are “validate | update | create | create-drop”

Step6). Now we will write a simple “index.jsp” page to just provide a some input forms so that a user can enter the employee name and id details , Place this file as well inside the “/home/userone/JPA_1_On_AS7/src” directory as following:

<html>
  <head>
     <title>JPA Demo In JBoss AS7</title>
  </head>
  <body>
     <form action="TestServlet">
       Enter Employee ID : <input name="empId" type="text" value="" /> <BR/>
       Enter Employee Name : <input name="empName" type="text" value="" /> <BR/>
       <input type="submit" value="Store" />
     </form>
  </body>
</html>

Step7). We will write the “TestServlet.java” inside the “/home/userone/JPA_1_On_AS7/src” as following in order to insert the details entered by the user in previous index.jsp page.

package servlets;
import java.io.IOException;
import java.io.PrintWriter;
import java.math.BigDecimal;
import javax.ejb.EJB;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import jpa.Employee;

@WebServlet(value="/TestServlet")
public class TestServlet extends HttpServlet 
  {
	private static final long serialVersionUID = 1L;

        @PersistenceContext(unitName="EmployeeService")
	EntityManager em;
	  
        @EJB(lookup="java:global/JPA_BASIC_Demo/EmployeeService!jpa.EmployeeServiceRemote")
        jpa.EmployeeServiceRemote remote;

	public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		try {
			System.out.println("inside TestServlet service()");
			System.out.println("Got Remote: "+remote);
			
			remote.createEmployee(new BigDecimal(request.getParameter("empId")),request.getParameter("empName"));
			PrintWriter out=response.getWriter();
                        out.println("<html><head><title>JPA Insert</title></head><body>");
			out.println("<BR>Employee Record Inserted in the Database.<BR>");
                        out.println("<TABLE border="10%">");
                        out.println("<TR><TD>EmpID</TD><TD>EmpName</TD></TR>");
			for(Employee tmp:remote.findAllEmployees())
			{
			   out.println("<TR><TD>"+tmp.getEmpno()+"</TD><TD>"+tmp.getEname()+"</TD></TR>");
			}
                        out.println("</TABLE>");
                        out.println("<BR><BR><a href="index.jsp"> Want to insert Some More Employee Records ?</a></body></html>");
		     } 
                 catch (Exception e) 
                     {
			e.printStackTrace();
		     }
	}
}

Step8). Now the most important part, here we are going to develop “build.xml” ANT file, which will build, deploy our web application on the JBoss AS7.1 Beta Server, so write the following “build.xml” file inside “/home/userone/JPA_1_On_AS7” directory.

<project name="JPA_BASIC_Demo" default="deploy">
<property name="jboss.home" value="/home/userone/jboss-as-7.1.0.Beta1" />
<property name="jboss.module.dir" value="${jboss.home}/modules" />
<property name="basedir" value="." />
<property name="tmp.dir" value="tmp" />
<property name="output.dir" value="build" />
<property name="src.dir" value="src" />
<property name="war.name" value="JPA_BASIC_Demo.war" />
 
   <path id="jboss.classpath">
     <fileset dir="${jboss.module.dir}">
        <include name="**/*.jar"/>
     </fileset>
   </path>
 
        <target name="init">
           <delete dir="${output.dir}" />
           <mkdir dir="${output.dir}" />
           <delete dir="${tmp.dir}" />
           <mkdir dir="${tmp.dir}" />
           <mkdir dir="${tmp.dir}/WEB-INF/classes/META-INF"/>
        </target>
 
        <target name="build" depends="init">
           <javac srcdir="${src.dir}" destdir="${tmp.dir}/WEB-INF/classes"  includes="*.java" classpathref="jboss.classpath" />
           <copy todir="${tmp.dir}/WEB-INF/classes">
                <fileset dir="${src.dir}" includes="**/*.java"/>
           </copy>
           <copy file="${src.dir}/index.jsp" tofile="${tmp.dir}/index.jsp"/>

           <!-- Make Sure that the persistence.xml file is placed inside "${war.name}/WEB-INF/classes/META-INF" directory -->
           <copy file="${src.dir}/persistence.xml" tofile="${tmp.dir}/WEB-INF/classes/META-INF/persistence.xml"/>

           <jar jarfile="${tmp.dir}/${war.name}" basedir="${tmp.dir}" compress="true" />
           <copy file="${tmp.dir}/${war.name}" tofile="${output.dir}/${war.name}"/>

           <delete includeEmptyDirs="true">
              <fileset dir="${tmp.dir}"/>
           </delete>

        </target>
 
        <target name="deploy" depends="build">
            <echo message="*******************  Deploying the WAR file ${war.name} *********************" />
            <echo message="********** ${output.dir}/${war.name} to ${jboss.home}/standalone/deployments **********" />
            <copy todir="${jboss.home}/standalone/deployments/">
                <fileset dir="${output.dir}/">
                  <include name="${war.name}"/>
                </fileset>
            </copy>
            <echo message="*******************  Deployed Successfully   *********************" />
        </target>
</project>

NOTE: The only change in the above file you need to do is to change the “jboss.home” directory path in the second line of the above script to point to your own JBoss AS7 directory.

Step9). Now before running your ANT script to build and deploy the above webapplication you should have the ANT as well as JAVA set in the $PATH variable of the Shell / command prompt as following:

For Unix Based OS:
export PATH=/home/userone/jdk1.6.0_21/bin:/home/userone/org.apache.ant_1.6.5/bin:$PATH

For Windows Based OS:
set PATH=C:/jdk1.6.0_21/bin;C:/org.apache.ant_1.6.5/bin;%PATH%

Step10). Now once the PATH is set In the command/Shell prompt you can move inside the directory “/home/userone/JPA_1_On_AS7” and then run the ant to build the webservice. by running the command “ant build”

Buildfile: /home/userone/JPA_1_On_AS7/build.xml

init:
   [delete] Deleting directory /home/userone/JPA_1_On_AS7/build
    [mkdir] Created dir: /home/userone/JPA_1_On_AS7/build
   [delete] Deleting directory /home/userone/JPA_1_On_AS7/tmp
    [mkdir] Created dir: /home/userone/JPA_1_On_AS7/tmp
    [mkdir] Created dir: /home/userone/JPA_1_On_AS7/tmp/WEB-INF/classes/META-INF

build:
    [javac] /home/userone/JPA_1_On_AS7/build.xml:25: warning: 'includeantruntime' was not set, defaulting to build.sysclasspath=last; set to false for repeatable builds
    [javac] Compiling 4 source files to /home/userone/JPA_1_On_AS7/tmp/WEB-INF/classes
     [copy] Copying 4 files to /home/userone/JPA_1_On_AS7/tmp/WEB-INF/classes
     [copy] Copying 1 file to /home/userone/JPA_1_On_AS7/tmp
     [copy] Copying 1 file to /home/userone/JPA_1_On_AS7/tmp/WEB-INF/classes/META-INF
      [jar] Building jar: /home/userone/JPA_1_On_AS7/tmp/JPA_BASIC_Demo.war
     [copy] Copying 1 file to /home/userone/JPA_1_On_AS7/build

deploy:
     [echo] *******************  Deploying the WAR file JPA_BASIC_Demo.war *********************
     [echo] ********** build/JPA_BASIC_Demo.war to /home/userone/jboss-as-7.1.0.Beta1/standalone/deployments **********
     [copy] Copying 1 file to /home/userone/jboss-as-7.1.0.Beta1/standalone/deployments
     [echo] *******************  Deployed Successfully   *********************

BUILD SUCCESSFUL
Total time: 2 seconds

Step11). Now you will see the following kind of output on your JBoss AS7.1 console which means the application is deployed successfully:

10:36:38,128 INFO  [org.hibernate.tool.hbm2ddl.SchemaExport] (MSC service thread 1-1) HHH000227: Running hbm2ddl schema export
10:36:38,131 INFO  [stdout] (MSC service thread 1-1) Hibernate: drop table if exists Employee
10:36:38,207 INFO  [org.hibernate.tool.hbm2ddl.SchemaExport] (MSC service thread 1-1) HHH000230: Schema export complete
10:36:38,213 INFO  [org.jboss.as.server.deployment] (MSC service thread 1-6) Stopped deployment JPA_BASIC_Demo.war in 90ms
10:36:38,214 INFO  [org.jboss.as.server.deployment] (MSC service thread 1-8) Starting deployment of "JPA_BASIC_Demo.war"
10:36:38,229 INFO  [org.jboss.jpa] (MSC service thread 1-8) JBAS011401: Read persistence.xml for EmployeeService
10:36:38,242 INFO  [org.jboss.as.ejb3.deployment.processors.EjbJndiBindingsDeploymentUnitProcessor] (MSC service thread 1-2) JNDI bindings for session bean named EmployeeService in deployment unit deployment "JPA_BASIC_Demo.war" are as follows:

	java:global/JPA_BASIC_Demo/EmployeeService!jpa.EmployeeServiceRemote
	java:app/JPA_BASIC_Demo/EmployeeService!jpa.EmployeeServiceRemote
	java:module/EmployeeService!jpa.EmployeeServiceRemote
	java:global/JPA_BASIC_Demo/EmployeeService
	java:app/JPA_BASIC_Demo/EmployeeService
	java:module/EmployeeService

10:36:38,264 INFO  [org.jboss.jpa] (MSC service thread 1-8) JBAS011402: Starting Persistence Unit Service 'JPA_BASIC_Demo.war#EmployeeService'
10:36:38,266 INFO  [org.hibernate.ejb.Ejb3Configuration] (MSC service thread 1-8) HHH000204: Processing PersistenceUnitInfo [
	name: EmployeeService
	...]
10:36:38,270 INFO  [org.hibernate.service.jdbc.connections.internal.ConnectionProviderInitiator] (MSC service thread 1-8) HHH000130: Instantiating explicit connection provider: org.hibernate.ejb.connection.InjectedDataSourceConnectionProvider
10:36:38,275 INFO  [org.hibernate.dialect.Dialect] (MSC service thread 1-8) HHH000400: Using dialect: org.hibernate.dialect.MySQLDialect
10:36:38,276 INFO  [org.hibernate.engine.jdbc.internal.LobCreatorBuilder] (MSC service thread 1-8) HHH000423: Disabling contextual LOB creation as JDBC driver reported JDBC version [3] less than 4
10:36:38,276 INFO  [org.hibernate.engine.transaction.internal.TransactionFactoryInitiator] (MSC service thread 1-8) HHH000268: Transaction strategy: org.hibernate.engine.transaction.internal.jta.CMTTransactionFactory
10:36:38,277 INFO  [org.hibernate.hql.internal.ast.ASTQueryTranslatorFactory] (MSC service thread 1-8) HHH000397: Using ASTQueryTranslatorFactory
10:36:38,284 INFO  [org.hibernate.tool.hbm2ddl.SchemaExport] (MSC service thread 1-8) HHH000227: Running hbm2ddl schema export
10:36:38,285 INFO  [stdout] (MSC service thread 1-8) Hibernate: drop table if exists Employee
10:36:38,287 INFO  [stdout] (MSC service thread 1-8) Hibernate: create table Employee (empno decimal(19,2) not null, ename varchar(255), primary key (empno))
10:36:38,438 INFO  [org.hibernate.tool.hbm2ddl.SchemaExport] (MSC service thread 1-8) HHH000230: Schema export complete
10:36:38,455 INFO  [org.jboss.web] (MSC service thread 1-1) registering web context: /JPA_BASIC_Demo
10:36:38,470 INFO  [org.jboss.as.server.controller] (DeploymentScanner-threads - 1) Replaced deployment "JPA_BASIC_Demo.war" with deployment "JPA_BASIC_Demo.war"

Step12). Now access the WebApplication like following :
http://localhost:8080/JPA_BASIC_Demo/index.jsp

.
.
Thanks
Middleware Magic Team

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