Sunday, March 27, 2011

Spring JPA: Many-To-One Association: Using Hibernate as the JPA Vendor

Introduction

In this tutorial we'll convert our previous project Spring - Hibernate: Many-To-One Association to use Spring JPA. We'll use Hibernate as the JPA provider and show the required changes to convert our project.

Spring MVC 3 and Hibernate Tutorials Series
Spring JPA: Many-To-One Association: Using Hibernate as the JPA Vendor
Spring JPA: One-To-Many Association: Using Hibernate as the JPA Vendor
Spring - Hibernate: Many-To-One Association - Explicitly Specify Join Table, Cascade, and Fetch
Spring - Hibernate: One-To-Many Association - Explicitly Specify Join Table, Cascade, and Fetch
Spring - Hibernate: Many-To-One Association
Spring - Hibernate: One-To-Many Association
Spring MVC 3, Hibernate Annotations, MySQL Integration Tutorial
Spring MVC 3, Hibernate Annotations, HSQLDB Integration Tutorial

What is Spring JPA?
The Spring JPA, available under the org.springframework.orm.jpa package, offers comprehensive support for the Java Persistence API in a similar manner to the integration with Hibernate or JDO, while being aware of the underlying implementation in order to provide additional features.

Source: Spring 3 Reference

What is JPA?
The Java Persistence API simplifies the programming model for entity persistence and adds capabilities that were not in EJB 2.1

The Java Persistence API deals with the way relational data is mapped to Java objects ("persistent entities"), the way that these objects are stored in a relational database so that they can be accessed at a later time, and the continued existence of an entity's state even after the application that uses it ends. In addition to simplifying the entity persistence model, the Java Persistence API standardizes object-relational mapping.

Source: The Java Persistence API - A Simpler Programming Model for Entity Persistence

Changes

Using a diff tool, we can visualize the changes from the original Hibernate project to the JPA project.


Development

Similar with the original project, we'll split our development in three layers: Domain, Service, and Controller.

Domain Layer

In the domain layer, we don't change any existing domain classes. That's because our domain is already using JPA annotation in the beginning.

Service Layer

For the service classes, we will drop all Hibernate references and instead use JPA. Let's start with the CreditCardService:

CreditCardService.java
package org.krams.tutorial.service;

import java.util.List;
import javax.annotation.Resource;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;

import org.apache.log4j.Logger;
import org.krams.tutorial.domain.CreditCard;
import org.krams.tutorial.domain.Person;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

/**
 * Service for processing Credit Cards
 * 
 * @author Krams at {@link http://krams915@blogspot.com
 */
@Service("creditCardService")
@Transactional
public class CreditCardService {

 protected static Logger logger = Logger.getLogger("service");

 @Resource(name="personService")
 private PersonService personService;
 
 private EntityManager entityManager;

    @PersistenceContext
    public void setEntityManager(EntityManager entityManager) {
        this. entityManager = entityManager;
    }
 
 /**
  * Retrieves all credit cards
  */
 public List<CreditCard> getAll(Integer personId) {
  logger.debug("Retrieving all credit cards");
  
  // Create a JPA query
  Query query = entityManager.createQuery("FROM  CreditCard WHERE person.id=" +personId);
  
  // Retrieve all
  return query.getResultList();
 }
 
 /**
  * Retrieves all credit cards
  */
 public List<CreditCard> getAll() {
  logger.debug("Retrieving all credit cards");
  
  // Create a JPA query
  Query query = entityManager.createQuery("FROM  CreditCard");
  
  // Retrieve all
  return query.getResultList();
 }
 
 /**
  * Retrieves a single credit card
  */
 public CreditCard get( Integer id ) {
  
  // Retrieve existing credit card
  CreditCard creditCard = (CreditCard) entityManager.createQuery("FROM CreditCard p WHERE p.id = :id")
      .setParameter("id", id).getSingleResult();

  // Persists to db
  return creditCard;
 }
 
 /**
  * Adds a new credit card
  */
 public void add(Integer personId, CreditCard creditCard) {
  logger.debug("Adding new credit card");
  
  // Retrieve existing person via id
  Person existingPerson = personService.get(personId);
  
  // Add person to credit card
  creditCard.setPerson(existingPerson);
  
  // Persists to db
  entityManager.merge(creditCard);
 }
 
 /**
  * Deletes an existing credit card
  */
 public void delete(Integer id) {
  logger.debug("Deleting existing credit card");
  
  // Retrieve existing credit card
  CreditCard creditCard = this.get(id);
  
  // Delete 
  entityManager.remove(creditCard);
 }
 
 /**
  * Deletes all credit cards based on the person's id
  */
 public void deleteAll(Integer personId) {
  logger.debug("Deleting existing credit cards based on person's id");
  
  // Create a JPA query
  Query query = entityManager.createQuery("DELETE FROM CreditCard WHERE person.id=" +personId);
  
  // Delete all
  query.executeUpdate();
 }
 
 /**
  * Edits an existing credit card
  */
 public void edit(CreditCard creditCard) {
  logger.debug("Editing existing creditCard");
  
  // Retrieve existing credit card via id
  CreditCard existingCreditCard = this.get(creditCard.getId());
  
  // Assign updated values to this credit card
  existingCreditCard.setNumber(creditCard.getNumber());
  existingCreditCard.setType(creditCard.getType());

  // Save updates
  entityManager.merge(existingCreditCard);
 }
}

Let's make a side-by-side comparison between the original Hibernate-based implementation and the new JPA-based implementation:

SessionFactory to EntityManager
To utilize JPA we have to remove Hibernate's SessionFactory and replace it with JPA's EntityManager. Essentially the EntityManager is equivalent to Hibernate's Session object.

old code
@Resource(name="sessionFactory")
private SessionFactory sessionFactory;

new code
@Resource(name="personService")
private PersonService personService;
 
private EntityManager entityManager;

@PersistenceContext
public void setEntityManager(EntityManager entityManager) {
        this. entityManager = entityManager;
}

Retrieve all credit cards by person's id
old code
/**
  * Retrieves all credit cards
  */
 public List<CreditCard> getAll(Integer personId) {
  logger.debug("Retrieving all credit cards");
  
  // Retrieve session from Hibernate
  Session session = sessionFactory.getCurrentSession();
  
  // Create a Hibernate query (HQL)
  Query query = session.createQuery("FROM  CreditCard WHERE person.id=" +personId);
  
  // Retrieve all
  return  query.list();
 }

new code
/**
  * Retrieves all credit cards
  */
 public List<CreditCard> getAll(Integer personId) {
  logger.debug("Retrieving all credit cards");
  
  // Create a JPA query
  Query query = entityManager.createQuery("FROM  CreditCard WHERE person.id=" +personId);
  
  // Retrieve all
  return query.getResultList();
 }

Retrieve all credit cards
old code
/**
  * Retrieves all credit cards
  */
 public List<CreditCard> getAll() {
  logger.debug("Retrieving all credit cards");
  
  // Retrieve session from Hibernate
  Session session = sessionFactory.getCurrentSession();
  
  // Create a Hibernate query (HQL)
  Query query = session.createQuery("FROM  CreditCard");
  
  // Retrieve all
  return  query.list();
 }

new code
/**
  * Retrieves all credit cards
  */
 public List<CreditCard> getAll() {
  logger.debug("Retrieving all credit cards");
  
  // Create a JPA query
  Query query = entityManager.createQuery("FROM  CreditCard");
  
  // Retrieve all
  return query.getResultList();
 }

Add new credit card
old code
/**
  * Adds a new credit card
  */
 public void add(Integer personId, CreditCard creditCard) {
  logger.debug("Adding new credit card");
  
  // Retrieve session from Hibernate
  Session session = sessionFactory.getCurrentSession();
  
  // Retrieve existing person via id
  Person existingPerson = (Person) session.get(Person.class, personId);
  
  // Add person to credit card
  creditCard.setPerson(existingPerson);
  
  // Persists to db
  session.save(creditCard);
 }

new code
/**
  * Adds a new credit card
  */
 public void add(Integer personId, CreditCard creditCard) {
  logger.debug("Adding new credit card");
  
  // Retrieve existing person via id
  Person existingPerson = personService.get(personId);
  
  // Add person to credit card
  creditCard.setPerson(existingPerson);
  
  // Persists to db
  entityManager.merge(creditCard);
 }

Retrieve a single credit card
old code
/**
  * Retrieves a single credit card
  */
 public CreditCard get( Integer id ) {
  // Retrieve session from Hibernate
  Session session = sessionFactory.getCurrentSession();
  
  // Retrieve existing credit card
  CreditCard creditCard = (CreditCard) session.get(CreditCard.class, id);
  
  // Persists to db
  return creditCard;
 }

new code
/**
  * Retrieves a single credit card
  */
 public CreditCard get( Integer id ) {
  
  // Retrieve existing credit card
  CreditCard creditCard = (CreditCard) entityManager.createQuery("FROM CreditCard p WHERE p.id = :id")
      .setParameter("id", id).getSingleResult();

  // Persists to db
  return creditCard;
 }

Delete an existing credit card
old code
/**
  * Deletes an existing credit card
  */
 public void delete(Integer id) {
  logger.debug("Deleting existing credit card");
  
  // Retrieve session from Hibernate
  Session session = sessionFactory.getCurrentSession();
  
  // Retrieve existing credit card
  CreditCard creditCard = (CreditCard) session.get(CreditCard.class, id);
  
  // Delete 
  session.delete(creditCard);
 }

new code
/**
  * Deletes an existing credit card
  */
 public void delete(Integer id) {
  logger.debug("Deleting existing credit card");
  
  // Retrieve existing credit card
  CreditCard creditCard = this.get(id);
  
  // Delete 
  entityManager.remove(creditCard);
 }

Delete all credit cards based on the person's id
old code
/**
  * Deletes all credit cards based on the person's id
  */
 public void deleteAll(Integer personId) {
  logger.debug("Deleting existing credit cards based on person's id");
  
  // Retrieve session from Hibernate
  Session session = sessionFactory.getCurrentSession();
  
  // Create a Hibernate query (HQL)
  Query query = session.createQuery("DELETE FROM CreditCard WHERE person.id=" +personId);
  
  // Delete all
  query.executeUpdate();
 }

new code
/**
  * Deletes all credit cards based on the person's id
  */
 public void deleteAll(Integer personId) {
  logger.debug("Deleting existing credit cards based on person's id");
  
  // Create a JPA query
  Query query = entityManager.createQuery("DELETE FROM CreditCard WHERE person.id=" +personId);
  
  // Delete all
  query.executeUpdate();
 }

Edit an existing credit card
old code
/**
  * Edits an existing credit card
  */
 public void edit(CreditCard creditCard) {
  logger.debug("Editing existing creditCard");
  
  // Retrieve session from Hibernate
  Session session = sessionFactory.getCurrentSession();
  
  // Retrieve existing credit card via id
  CreditCard existingCreditCard = (CreditCard) session.get(CreditCard.class, creditCard.getId());
  
  // Assign updated values to this credit card
  existingCreditCard.setNumber(creditCard.getNumber());
  existingCreditCard.setType(creditCard.getType());

  // Save updates
  session.save(existingCreditCard);
 }

new code
/**
  * Edits an existing credit card
  */
 public void edit(CreditCard creditCard) {
  logger.debug("Editing existing creditCard");
  
  // Retrieve existing credit card via id
  CreditCard existingCreditCard = this.get(creditCard.getId());
  
  // Assign updated values to this credit card
  existingCreditCard.setNumber(creditCard.getNumber());
  existingCreditCard.setType(creditCard.getType());

  // Save updates
  entityManager.merge(existingCreditCard);
 }

PersonService.java
package org.krams.tutorial.service;

import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;

import org.apache.log4j.Logger;
import org.krams.tutorial.domain.Person;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

/**
 * Service for processing Persons
 * 
 * @author Krams at {@link http://krams915@blogspot.com
 */
@Service("personService")
@Transactional
public class PersonService {

 protected static Logger logger = Logger.getLogger("service");
 
 private EntityManager entityManager;

    @PersistenceContext
    public void setEntityManager(EntityManager entityManager) {
        this. entityManager = entityManager;
    }
    
 /**
  * Retrieves all persons
  * 
  * @return a list of persons
  */
 public List<Person> getAll() {
  logger.debug("Retrieving all persons");
  
  // Create a JPA query
  Query query  = entityManager.createQuery("FROM Person");
  
  // Retrieve all
  return query.getResultList();
 }
 
 /**
  * Retrieves a single person
  */
 public Person get( Integer id ) {
  
  // Retrieve existing person
  Person person = (Person) entityManager.createQuery("FROM Person p where p.id = :id")
         .setParameter("id", id).getSingleResult();
  
  return person;
 }
 
 /**
  * Adds a new person
  */
 public void add(Person person) {
  logger.debug("Adding new person");
  
  // Persists to db
  entityManager.persist(person);
 }
 
 /**
  * Deletes an existing person
  * @param id the id of the existing person
  */
 public void delete(Integer id) {
  logger.debug("Deleting existing person");
  
  // Retrieve existing person
  Person person = this.get(id);
  
  // Delete 
  entityManager.remove(person);
 }
 
 /**
  * Edits an existing person
  */
 public void edit(Person person) {
  logger.debug("Editing existing person");
  
  // Retrieve existing person via id
  Person existingPerson = this.get(person.getId());
  
  // Assign updated values to this person
  existingPerson.setFirstName(person.getFirstName());
  existingPerson.setLastName(person.getLastName());
  existingPerson.setMoney(person.getMoney());

  // Save updates
  entityManager.merge(person);
 }
}

Let's make a side-by-side comparison between the original Hibernate-based implementation and the new JPA-based implementation:

SessionFactory to EntityManager
Similar with the CreditCardService, we have to remove Hibernate's SessionFactory and replace it with JPA's EntityManager.

old code
@Resource(name="sessionFactory")
private SessionFactory sessionFactory;

new code
private EntityManager entityManager;

    @PersistenceContext
    public void setEntityManager(EntityManager entityManager) {
        this. entityManager = entityManager;
    }


Retrieve all persons
old code
/**
  * Retrieves all persons
  * 
  * @return a list of persons
  */
 public List getAll() {
  logger.debug("Retrieving all persons");
  
  // Retrieve session from Hibernate
  Session session = sessionFactory.getCurrentSession();
  
  // Create a Hibernate query (HQL)
  Query query = session.createQuery("FROM  Person");
  
  // Retrieve all
  return  query.list();
 }

new code
/**
  * Retrieves all persons
  * 
  * @return a list of persons
  */
 public List getAll() {
  logger.debug("Retrieving all persons");
  
  // Create a JPA query
  Query query  = entityManager.createQuery("FROM Person");
  
  // Retrieve all
  return query.getResultList();
 }

Retrieve a single person
old code
/**
  * Retrieves a single person
  */
 public Person get( Integer id ) {
  // Retrieve session from Hibernate
  Session session = sessionFactory.getCurrentSession();
  
  // Retrieve existing person
  Person person = (Person) session.get(Person.class, id);
  
  return person;
 }

new code
/**
  * Retrieves a single person
  */
 public Person get( Integer id ) {
  
  // Retrieve existing person
  Person person = (Person) entityManager.createQuery("FROM Person p where p.id = :id")
         .setParameter("id", id).getSingleResult();
  
  return person;
 }

Add a new person
old code
/**
  * Adds a new person
  */
 public void add(Person person) {
  logger.debug("Adding new person");
  
  // Retrieve session from Hibernate
  Session session = sessionFactory.getCurrentSession();
  
  // Persists to db
  session.save(person);
 }

new code
/**
  * Adds a new person
  */
 public void add(Person person) {
  logger.debug("Adding new person");
  
  // Persists to db
  entityManager.persist(person);
 }


Delete an existing person
old code
/**
  * Deletes an existing person
  * @param id the id of the existing person
  */
 public void delete(Integer id) {
  logger.debug("Deleting existing person");
  
  // Retrieve session from Hibernate
  Session session = sessionFactory.getCurrentSession();
  
  // Retrieve existing person
  Person person = (Person) session.get(Person.class, id);
  
  // Delete 
  session.delete(person);
 }

new code
/**
  * Deletes an existing person
  * @param id the id of the existing person
  */
 public void delete(Integer id) {
  logger.debug("Deleting existing person");
  
  // Retrieve existing person
  Person person = this.get(id);
  
  // Delete 
  entityManager.remove(person);
 }

Edit an existing person
old code
/**
  * Edits an existing person
  */
 public void edit(Person person) {
  logger.debug("Editing existing person");
  
  // Retrieve session from Hibernate
  Session session = sessionFactory.getCurrentSession();
  
  // Retrieve existing person via id
  Person existingPerson = (Person) session.get(Person.class, person.getId());
  
  // Assign updated values to this person
  existingPerson.setFirstName(person.getFirstName());
  existingPerson.setLastName(person.getLastName());
  existingPerson.setMoney(person.getMoney());

  // Save updates
  session.save(existingPerson);
 }

new code
/**
  * Edits an existing person
  */
 public void edit(Person person) {
  logger.debug("Editing existing person");
  
  // Retrieve existing person via id
  Person existingPerson = this.get(person.getId());
  
  // Assign updated values to this person
  existingPerson.setFirstName(person.getFirstName());
  existingPerson.setLastName(person.getLastName());
  existingPerson.setMoney(person.getMoney());

  // Save updates
  entityManager.merge(person);
 }

Controller Layer

For the controller layer, we just need to fix a mapping bug when adding a new CreditCard. Everything else are the same:

CreditCardController.java
package org.krams.tutorial.controller;

import javax.annotation.Resource;

import org.apache.log4j.Logger;
import org.krams.tutorial.domain.CreditCard;
import org.krams.tutorial.service.CreditCardService;
import org.krams.tutorial.service.PersonService;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;


/**
 * Handles and retrieves person request
 * 
 * @author Krams at {@link http://krams915@blogspot.com
 */
@Controller
@RequestMapping("/main/creditcard")
public class CreditCardController {

 protected static Logger logger = Logger.getLogger("controller");
 
 @Resource(name="personService")
 private PersonService personService;
 
 @Resource(name="creditCardService")
 private CreditCardService creditCardService;
 
    /**
     * Retrieves the "Add New Credit Card" page
     */
    @RequestMapping(value = "/add", method = RequestMethod.GET)
    public String getAdd(@RequestParam("id") Integer personId, Model model) {
     logger.debug("Received request to show add page");
    
     // Prepare model object
     CreditCard creditCard = new CreditCard();
     creditCard.setPerson(personService.get(personId));
     
     // Add to model
     model.addAttribute("creditCardAttribute", creditCard);

     // This will resolve to /WEB-INF/jsp/add-credit-card.jsp
     return "add-credit-card";
 }
 
    /**
     * Adds a new credit card
     */
    @RequestMapping(value = "/add", method = RequestMethod.POST)
    public String postAdd(@RequestParam("pid") Integer personId, 
              @ModelAttribute("creditCardAttribute") CreditCard creditCard) {
  logger.debug("Received request to add new credit card");
  
  // Delegate to service
  creditCardService.add(personId, creditCard);

  // Redirect to url
  return "redirect:/krams/main/record/list";
 }
    
    
    /**
     * Deletes a credit card
     */
    @RequestMapping(value = "/delete", method = RequestMethod.GET)
    public String getDelete(@RequestParam("id") Integer creditCardId) {
     logger.debug("Received request to delete credit card");
    
     // Delegate to service
  creditCardService.delete(creditCardId);

  // Redirect to url
  return "redirect:/krams/main/record/list";
 }
   
    /**
     * Retrieves the "Edit Existing Credit Card" page
     */
    @RequestMapping(value = "/edit", method = RequestMethod.GET)
    public String getEdit(@RequestParam("id") Integer creditCardId, Model model) {
     logger.debug("Received request to show edit page");
     
     // Retrieve credit card by id
     CreditCard existingCreditCard = creditCardService.get(creditCardId);

     // Add to model
     model.addAttribute("creditCardAttribute", existingCreditCard);

     // This will resolve to /WEB-INF/jsp/edit-credit-card.jsp
     return "edit-credit-card";
 }
 
    /**
     * Edits an existing credit card
     */
    @RequestMapping(value = "/edit", method = RequestMethod.POST)
    public String postEdit(@RequestParam("id") Integer creditCardId, 
              @ModelAttribute("creditCardAttribute") CreditCard creditCard) {
  logger.debug("Received request to add new credit card");
  
  // Assign id
  creditCard.setId(creditCardId);
  
  // Delegate to service
  creditCardService.edit(creditCard);

  // Redirect to url
  return "redirect:/krams/main/record/list";
 }
}

Here's the change we did for the CreditCardController:

Add a new credit card
We simply changed the @RequestParam("id") to @RequestParam("pid"):
old code
/**
     * Adds a new credit card
     */
    @RequestMapping(value = "/add", method = RequestMethod.POST)
    public String postAdd(@RequestParam("id") Integer personId, 
              @ModelAttribute("creditCardAttribute") CreditCard creditCard) {
  logger.debug("Received request to add new credit card");
  
  // Delegate to service
  creditCardService.add(personId, creditCard);

  // Redirect to url
  return "redirect:/krams/main/record/list";
 }

new code
/**
     * Adds a new credit card
     */
    @RequestMapping(value = "/add", method = RequestMethod.POST)
    public String postAdd(@RequestParam("pid") Integer personId, 
              @ModelAttribute("creditCardAttribute") CreditCard creditCard) {
  logger.debug("Received request to add new credit card");
  
  // Delegate to service
  creditCardService.add(personId, creditCard);

  // Redirect to url
  return "redirect:/krams/main/record/list";
 }

Since we've modified the @RequestMapping for the Add page, we have to update our add-credit-card.jsp

add-credit-card.jsp
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ taglib uri="http://www.springframework.org/tags/form" prefix="form" %>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    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>Insert title here</title>
</head>
<body>

<h1>Add New Credit Card</h1>

<c:url var="saveUrl" value="/krams/main/creditcard/add?pid=${creditCardAttribute.person.id}" />
<form:form modelAttribute="creditCardAttribute" method="POST" action="${saveUrl}">
 <table>
 
  <tr>
   <td><form:label path="person.id">Person Id:</form:label></td>
   <td><form:input path="person.id" disabled="true"/></td>
  </tr>
  
  <tr>
   <td><form:label path="type">Type:</form:label></td>
   <td><form:input path="type"/></td>
  </tr>

  <tr>
   <td><form:label path="number">Number:</form:label></td>
   <td><form:input path="number"/></td>
  </tr>
 </table>
 
 <input type="submit" value="Save" />
</form:form>

</body>
</html>

Here's the change we did for the add-credit-card.jsp:
old
<c:url var="saveUrl" value="/krams/main/creditcard/add?id=${creditCardAttribute.person.id}" />

new
<c:url var="saveUrl" value="/krams/main/creditcard/add?pid=${creditCardAttribute.person.id}" />


Configuration

We have completed the necessary Java classes. Our next step is to update our configuration files.

Here are the steps:

1. Update our hibernate-context.xml so that it uses JPA. Here's the updated config:
hibernate-context.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans  xmlns="http://www.springframework.org/schema/beans" 
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:p="http://www.springframework.org/schema/p" 
        xmlns:tx="http://www.springframework.org/schema/tx"
        xmlns:context="http://www.springframework.org/schema/context"
        xsi:schemaLocation="
   http://www.springframework.org/schema/beans 
   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
   http://www.springframework.org/schema/tx 
   http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
   http://www.springframework.org/schema/context
   http://www.springframework.org/schema/context/spring-context-3.0.xsd
      ">

 <context:property-placeholder location="/WEB-INF/spring.properties" />
 
 <tx:annotation-driven transaction-manager="transactionManager" /> 
 
 <!-- Declare a datasource that has pooling capabilities-->  
 <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"
    destroy-method="close"
    p:driverClass="${app.jdbc.driverClassName}"
    p:jdbcUrl="${app.jdbc.url}"
    p:user="${app.jdbc.username}"
    p:password="${app.jdbc.password}"
    p:acquireIncrement="5"
    p:idleConnectionTestPeriod="60"
    p:maxPoolSize="100"
    p:maxStatements="50"
    p:minPoolSize="10" />

  <!-- Declare a JPA entityManagerFactory-->
 <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean" >
  <property name="persistenceXmlLocation" value="classpath*:META-INF/persistence.xml"></property>
  <property name="persistenceUnitName" value="hibernatePersistenceUnit" />
  <property name="dataSource" ref="dataSource"/>
     <property name="jpaVendorAdapter">
         <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" >
             <property name="showSql" value="true"/>
         </bean>
     </property>
    </bean>

 <!-- Declare a transaction manager-->
 <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
     <property name="entityManagerFactory" ref="entityManagerFactory" />
 </bean>  
</beans>


Here's the change we did for the hibernate-context.xml:
Remove the following lines:
<!-- Declare the Hibernate SessionFactory for retrieving Hibernate sessions -->
    <!-- See http://static.springsource.org/spring/docs/3.0.x/javadoc-api/org/springframework/orm/hibernate3/annotation/AnnotationSessionFactoryBean.html -->        
 <!-- See http://docs.jboss.org/hibernate/stable/core/api/index.html?org/hibernate/SessionFactory.html -->
 <!-- See http://docs.jboss.org/hibernate/stable/core/api/index.html?org/hibernate/Session.html -->
 <bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean"
     p:dataSource-ref="dataSource"
     p:configLocation="${hibernate.config}"
     p:packagesToScan="org.krams.tutorial"/>

 <!-- Declare a transaction manager-->
 <bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager" 
          p:sessionFactory-ref="sessionFactory" />

And replace it with:
<!-- Declare a JPA entityManagerFactory-->
 <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean" >
  <property name="persistenceXmlLocation" value="classpath*:META-INF/persistence.xml"></property>
  <property name="persistenceUnitName" value="hibernatePersistenceUnit" />
  <property name="dataSource" ref="dataSource"/>
     <property name="jpaVendorAdapter">
         <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" >
             <property name="showSql" value="true"/>
         </bean>
     </property>
    </bean>

 <!-- Declare a transaction manager-->
 <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
     <property name="entityManagerFactory" ref="entityManagerFactory" />
 </bean>  
</beans>

2. Delete the hibernate.cfg.xml.

3. Declare a META-INF/persistence.xml

<persistence xmlns="http://java.sun.com/xml/ns/persistence" version="1.0">

  <persistence-unit name="hibernatePersistenceUnit" transaction-type="RESOURCE_LOCAL">
    <properties>
   <property name="hibernate.hbm2ddl.auto" value="create" />
  </properties>
  </persistence-unit>

</persistence>

Run the Application

Run the Application


Setup the database

Our application uses MySQL as its database. To run the application, make sure to setup the database first.

To create the database, follow these steps.
1. Open phpmyadmin (or any tool you prefer with)
2. Create a new database named mydatabase
3. Run the application to automatically create the database schema.

To populate the database with sample data, import the mydatabase.sql SQL script which is located under the WEB-INF folder of the application.

Access the main application

To access the main application, use the following URL:
http://localhost:8080/spring-hibernate-jpa-many-to-one-default/krams/main/record/list

You should see the following application:


Conclusion

That's it. We've successfully updated our original Hibernate-based application to Spring JPA-based implementation. The advantage of this project is we can now switch JPA providers seamlessly without any direct dependencies with Hibernate.

Download the project
You can access the project site at Google's Project Hosting at http://code.google.com/p/spring-mvc-hibernate-annotations-integration-tutorial/

You can download the project as a Maven build. Look for the spring-hibernate-jpa-many-to-one-default.zip in the Download sections.

You can run the project directly using an embedded server via Maven.
For Tomcat: mvn tomcat:run
For Jetty: mvn jetty:run

If you want to learn more about Spring MVC and integration with other technologies, feel free to read my other tutorials in the Tutorials section.
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9 comments:

  1. This was so useful! Thank you so much!

    ReplyDelete
  2. hello, this is very good information for me i am looking for it i have search many websites,but know i get the actual information thanks.Kashmir,glory of India, is poetry of nature. The beauty of Kashmir has always attracted travelers and emperors alike to appreciate the enchanting wonder that Kashmir is. A Kashmir Tour Packages is an experience of a lifetime, unforgettable in every way. The Kashmir holidays experience is no less splendid than a most beautiful dream, the kind of which we see with our eyes open. From the quiet sunset on Dal Lake in Srinagar to the thrilling rush of white water rafting adventure sports of Gulmarg, Kashmir has a plethora of unforgettable experiences to offer to the traveler. In fact, the beauty of Kashmir can be summarized into three distinct categories, the foothill plains of Jammu, the beautiful lakes and valleys of Kashmir (Gulmarg, Sonmarg, Pahalgam, Srinagar etc) and the magnificent mountains of Ladakh and Leh. This is the reason we offer tour packages encompassing these three distinct regions of Kashmir. Kashmir is also a holy land with pilgrims visiting the Amaranth Siva-Linga made of ice and also the Vaishno Devi temple pilgrimage. Therefore, if you are a pilgrim to Kashmir, you should choose the tour package that takes you on your pilgrimage.

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  3. Your tutorials are better than the sample apps provided by Springsource. This is some of the most concise "how to" Spring information I've seen (and I've seen a lot!).

    Thank you so much for taking the time to show us and explain the complexities of the Spring API.

    Can you do one on Spring Security with RESTful API? : )

    ReplyDelete
  4. Very nice. freely receive, freely give indeed. I've subscribed you. I would definitely love spring security for RESTful api user authentication and authorization tutorial for server and client! :)

    Cheers.

    ReplyDelete
  5. Thanks for great tutorial.
    I have one problem. When i run the tomcat server, the all records in my database are removing. I use MySQL. Have you got similar problem and tell me what is wrong? (sorry for my english)

    ReplyDelete
  6. [ERROR] [localhost-startStop-1 04:52:09] (JDBCExceptionReporter.java:logExceptions:101) Connections could not be acquired from the underlying database!
    [ERROR] [localhost-startStop-1 04:52:28] (JDBCExceptionReporter.java:logExceptions:101) Connections could not be acquired from the underlying database!
    [ERROR] [localhost-startStop-1 04:52:28] (SchemaExport.java:execute:274) schema export unsuccessful
    why this happen?

    ReplyDelete
  7. I have read your blog its very attractive and impressive. I like it your blog.

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