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.

JBoss also provides feature to deploy JAX-RS based applications including package “org.jboss.resteasy.*”. Here in this example we will see how to integrate the Resteasy wtih JPA. In this process we will see how to use various annotations like @XmlRootElement, @ApplicationPath @Entity @PersistenceContext etc.. A Quick tour on JAX-RS Reference Guide will be better.

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: 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 using the JAX-RS as frontend. 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). How to use the JAX-RS resteasy implementations and various annotations associated with it.

<<< I S S U E >>>: I tried to use the @javax.ejb.EJB annotation to inject an Enterprise Java Bean inside Rest Easy component but it did not work Like @EJB(lookup=”jndiName”) , which need to be checked (May be it’s work as designed). But it worked fine inside a Servlet in another case.

Server Side Configuration

Point-1). Here we are using JBoss AS7 latest build “jboss-as-7.1.0.CR1” 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.CR1/bin” directory as following:

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

Developing JPA Part Of the Test Case

Step1). Create a directory somewhere in your filesystem like “/home/userone/JPA2_JAXRS_And_Hibernate4_On_AS7” where we will place our application build related stuff. Then create another directory “src” inside “/home/userone/JPA2_JAXRS_And_Hibernate4_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/JPA2_JAXRS_And_Hibernate4_On_AS7/src” directory. NOTICE: we used the annotation “@XmlRootElement”

package jpa;
import java.io.Serializable;
import javax.persistence.*;
import javax.xml.bind.annotation.XmlRootElement;

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

	@Id
	private Integer empno;
	private String ename;

        public Employee() {
    	 System.out.println("[Employee] Employee Object Created. "+this);
        }

	public Integer getEmpno() {
                System.out.println("[Employee] getEmpno() called on "+this);
		return this.empno;
	}

	public void setEmpno(Integer empno) {
                System.out.println("[Employee] setEmpno("+empno+") called on "+this);
		this.empno = empno;
	}

	public String getEname() {
                System.out.println("[Employee] getEname() called on "+this);
		return this.ename;
	}

	public void setEname(String ename) {
                System.out.println("[Employee] setEname("+ename+") called on "+this);
		this.ename = ename;
	}

}

Step3). Now we will create a Simple Stateless SessionBean remote Interface “EmployeeServiceRemote.java” inside “/home/userone/JPA2_JAXRS_And_Hibernate4_On_AS7/src” directory as following:

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

public interface EmployeeServiceRemote{
  public void doAction();
  public Employee createEmployee(Integer id, String name);
  public void removeEmployee(Integer id);
  public Employee findEmployee(Integer 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/JPA2_JAXRS_And_Hibernate4_On_AS7/src” directory as following:

package jpa;
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("n[EmployeeService] EmployeeService Created. this: "+this);
  }

  public Employee createEmployee(Integer id, String name) {
    Employee emp = new Employee();
    emp.setEmpno(id);
    emp.setEname(name);
    em.persist(emp);
    emp = findEmployee(id);
    System.out.println("n[EmployeeService] Inside createEmployee() findEmployee result: "+emp+"t this: "+this);
    em.flush();
    return emp;
  }

  public void removeEmployee(Integer id) {
    System.out.println("n[EmployeeService] Inside removeEmployee("+id+") this: "+this);
    Employee emp = findEmployee(id);
    if (emp != null) {
      em.remove(emp);
    }
  }

  public Employee findEmployee(Integer id) {
    System.out.println("n[EmployeeService] Inside findEmployee("+id+") this: "+this);
    return em.find(Employee.class, id);
  }

  @SuppressWarnings("unchecked")
  public Collection<Employee> findAllEmployees() {
    System.out.println("n[EmployeeService] Inside findAllEmployees() this: "+this);
    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/JPA2_JAXRS_And_Hibernate4_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”

Developing JAX-RS Part Of the Test Case

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/JPA2_JAXRS_And_Hibernate4_On_AS7/src” directory as following:

<html>
<head>
<title>JPA With Rest Demo In JBoss AS7</title>
</head>
<body>

<h1>Add An Employee</h1>
   <table border="10%">
      <form action="services/create" method="post">
         <TR><TD>Enter Employee ID </TD><TD> <input name="empno" type="text" value="" /> </TD></TR>
         <TR><TD>Enter Employee Name </TD><TD> <input name="empname" type="text" value="" /> </TD></TR>
         <TR><TD><input type="submit" value="Add Employee" /></TD><TD> <input type="reset" value="Clear" /></TD></TR>
      </form>
    </table>

<h1>Remove An Employee</h1>
   <table border="10%">
     <form action="services/removeemployee" method="post">
         <TR><TD>Enter Employee ID </TD><TD> <input name="empno" type="text" value=""/> </TD></TR>
         <TR><TD></TD><TD><input type="submit" value="Remove Employee" /></TD></TR>
   </form>
    </table>

<h1>Find An Employee</h1>
   <table border="10%">
      <form action="services/findemployee" method="post">
         <TR><TD>Enter Employee ID </TD><TD> <input name="empno" type="text" value=""/> </TD></TR>
         <TR><TD></TD><TD><input type="submit" value="Find Employee" /></TD></TR>
      </form>
    </table>

<h1>Find All Employees</h1>
   <a href="services/findall">Find All Employees</a>  

</body>
</html>

Step7). We will write the “MyRestService.java” inside the “/home/userone/JPA2_JAXRS_And_Hibernate4_On_AS7/src” as following in order to insert the details entered by the user in previous index.jsp page.

package rest;
import java.util.Collection;

//Rest related imports
import javax.ws.rs.Consumes;
import javax.ws.rs.GET;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.FormParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.ApplicationPath;
import javax.ws.rs.core.Application;

// EJB Related imports
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.ejb.EJB;
import jpa.Employee;
import jpa.EmployeeServiceRemote;

@ApplicationPath("/services")
@Path("/")
public class MyRestService extends Application
{
   /* ::::NOTE::::
        The Following Injection is not Working which need to be checked. So Here i am doing the old style lookup for the EJB.

        @EJB(lookup="java:global/JPA_BASIC_Demo/EmployeeService!jpa.EmployeeServiceRemote")
        jpa.EmployeeServiceRemote remote;
   */

  jpa.EmployeeServiceRemote remote;
  public MyRestService()
     {
       try{
            InitialContext ctx=new InitialContext();
            remote = (EmployeeServiceRemote) ctx.lookup("java:global/JPA_BASIC_Demo/EmployeeService!jpa.EmployeeServiceRemote");
          }
       catch(NamingException ne) 
          {
            System.out.println("n[MyRestService]NamingException: "+ne);
            ne.printStackTrace();
          }
     }


  @POST
  @Path("/create")
  @Produces(MediaType.APPLICATION_XML)  
  @Consumes("application/x-www-form-urlencoded")
  public Employee createEmployee(@FormParam("empno") Integer id, @FormParam("empname") String name) 
    {
        System.out.println("n[MyRestService]jpa.EmployeeServiceRemote remote = "+remote);
        Employee emp=null;
        if(remote!=null)
           emp=remote.createEmployee(id,name);
        else
          {
           emp=new Employee();
           emp.setEname(name);
           emp.setEmpno(id);
          }
        return emp;
    }        


  @POST
  @Path("/removeemployee")
  @Consumes("application/x-www-form-urlencoded")
  @Produces(MediaType.TEXT_HTML)  
  public String removeEmployee(@FormParam("empno") Integer id) 
    {
        System.out.println("n[MyRestService]Inside removeEmployee("+id+") this: "+this);
        remote.removeEmployee(id);
        return "Emplloyee Removed with Id: "+id;
    }


  @POST
  @Path("/findemployee")
  @Produces(MediaType.APPLICATION_XML)  
  @Consumes("application/x-www-form-urlencoded")
  public Employee findEmployee(@FormParam("empno") Integer id) 
    {
        System.out.println("n[MyRestService]Inside findEmployee("+id+") this: "+this);
        Employee emp=remote.findEmployee(id);
        return  emp;
    }


  @GET
  @Produces(MediaType.APPLICATION_XML)  
  @Path("/findall")
  public Collection<Employee> findAllEmployees() 
   {
       System.out.println("n[MyRestService]Inside findAllEmployees() this: "+this);
       Collection<Employee> collection=remote.findAllEmployees();
       return collection;
   }
}

Step8). As this is going to be a WebApplication so we will provide a simple default “web.xml” file inside “/home/userone/JPA2_JAXRS_And_Hibernate4_On_AS7/src” directory as following:

<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">

</web-app>

Building and deploying the Application

Step9). 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 CR1 Server, so write the following “build.xml” file inside “/home/userone/JPA2_JAXRS_And_Hibernate4_On_AS7” directory.

<project name="JPA_BASIC_Demo" default="deploy">
<property name="jboss.home" value="/home/userone/jboss-as-7.1.0.CR1" />
<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_With_JAXRS_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"/>
           <copy file="${src.dir}/web.xml" tofile="${tmp.dir}/web.xml"/>

           <!-- 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.

Step10). 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%

Step11). Now once the PATH is set In the command/Shell prompt you can move inside the directory “/home/userone/JPA2_JAXRS_And_Hibernate4_On_AS7” and then run the ant to build the webservice. by running the command “ant”

[userone@localhost JPA2_JAXRS_And_Hibernate4_On_AS7]$ ant
Buildfile: /home/userone/JPA2_JAXRS_And_Hibernate4_On_AS7/build.xml

init:
   [delete] Deleting directory /home/userone/JPA2_JAXRS_And_Hibernate4_On_AS7/build
    [mkdir] Created dir: /home/userone/JPA2_JAXRS_And_Hibernate4_On_AS7/build
    [mkdir] Created dir: /home/userone/JPA2_JAXRS_And_Hibernate4_On_AS7/tmp
    [mkdir] Created dir: /home/userone/JPA2_JAXRS_And_Hibernate4_On_AS7/tmp/WEB-INF/classes/META-INF

build:
    [javac] /home/userone/JPA2_JAXRS_And_Hibernate4_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/JPA2_JAXRS_And_Hibernate4_On_AS7/tmp/WEB-INF/classes
     [copy] Copying 4 files to /home/userone/JPA2_JAXRS_And_Hibernate4_On_AS7/tmp/WEB-INF/classes
     [copy] Copying 1 file to /home/userone/JPA2_JAXRS_And_Hibernate4_On_AS7/tmp
     [copy] Copying 1 file to /home/userone/JPA2_JAXRS_And_Hibernate4_On_AS7/tmp
     [copy] Copying 1 file to /home/userone/JPA2_JAXRS_And_Hibernate4_On_AS7/tmp/WEB-INF/classes/META-INF
      [jar] Building jar: /home/userone/JPA2_JAXRS_And_Hibernate4_On_AS7/tmp/JPA_With_JAXRS_BASIC_Demo.war
     [copy] Copying 1 file to /home/userone/JPA2_JAXRS_And_Hibernate4_On_AS7/build

deploy:
     [echo] *******************  Deploying the WAR file JPA_With_JAXRS_BASIC_Demo.war *********************
     [echo] ********** build/JPA_With_JAXRS_BASIC_Demo.war to //home/userone/jboss-as-7.1.0.CR1/standalone/deployments **********
     [copy] Copying 1 file to //home/userone/jboss-as-7.1.0.CR1/standalone/deployments
     [echo] *******************  Deployed Successfully   *********************

BUILD SUCCESSFUL
Total time: 2 seconds

Step12). Now you will see the following kind of output on your JBoss AS7.1 console which means the application is deployed successfully:

20:21:15,570 INFO  [org.jboss.as.server.deployment] (MSC service thread 1-1) Starting deployment of "JPA_With_JAXRS_BASIC_Demo.war"
20:21:15,589 INFO  [org.jboss.jpa] (MSC service thread 1-2) JBAS011401: Read persistence.xml for EmployeeService
20:21:15,598 INFO  [org.jboss.as.ejb3.deployment.processors.EjbJndiBindingsDeploymentUnitProcessor] (MSC service thread 1-3) JNDI bindings for session bean named EmployeeService in deployment unit deployment "JPA_With_JAXRS_BASIC_Demo.war" are as follows:

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

20:21:15,617 INFO  [org.jboss.jpa] (MSC service thread 1-6) JBAS011402: Starting Persistence Unit Service 'JPA_With_JAXRS_BASIC_Demo.war#EmployeeService'
20:21:15,619 INFO  [org.hibernate.ejb.Ejb3Configuration] (MSC service thread 1-6) HHH000204: Processing PersistenceUnitInfo [
	name: EmployeeService
	...]
20:21:15,628 INFO  [org.hibernate.service.jdbc.connections.internal.ConnectionProviderInitiator] (MSC service thread 1-6) HHH000130: Instantiating explicit connection provider: org.hibernate.ejb.connection.InjectedDataSourceConnectionProvider
20:21:15,635 INFO  [org.hibernate.dialect.Dialect] (MSC service thread 1-6) HHH000400: Using dialect: org.hibernate.dialect.MySQLDialect
20:21:15,635 INFO  [org.hibernate.engine.jdbc.internal.LobCreatorBuilder] (MSC service thread 1-6) HHH000423: Disabling contextual LOB creation as JDBC driver reported JDBC version [3] less than 4
20:21:15,636 INFO  [org.hibernate.engine.transaction.internal.TransactionFactoryInitiator] (MSC service thread 1-6) HHH000268: Transaction strategy: org.hibernate.engine.transaction.internal.jta.CMTTransactionFactory
20:21:15,636 INFO  [org.hibernate.hql.internal.ast.ASTQueryTranslatorFactory] (MSC service thread 1-6) HHH000397: Using ASTQueryTranslatorFactory
20:21:15,643 INFO  [org.hibernate.tool.hbm2ddl.SchemaExport] (MSC service thread 1-6) HHH000227: Running hbm2ddl schema export
20:21:15,643 INFO  [stdout] (MSC service thread 1-6) Hibernate: drop table if exists Employee
20:21:15,645 INFO  [stdout] (MSC service thread 1-6) Hibernate: create table Employee (empno integer not null, ename varchar(255), primary key (empno))
20:21:15,768 INFO  [org.hibernate.tool.hbm2ddl.SchemaExport] (MSC service thread 1-6) HHH000230: Schema export complete
20:21:15,776 INFO  [org.jboss.web] (MSC service thread 1-4) registering web context: /JPA_With_JAXRS_BASIC_Demo
20:21:15,788 INFO  [org.jboss.as.server] (DeploymentScanner-threads - 1) JBAS018559: Deployed "JPA_With_JAXRS_BASIC_Demo.war"

Step13). Now access the WebApplication like following :
http://localhost:8080/JPA_With_JAXRS_BASIC_Demo/

JPA_With_JAXRS


.
.
Thanks 🙂
Middleware Magic Team

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