Spring 4 and Hibernate 4 integration tutorial part 1 xml configuration

In enterprise Java application development, perhaps Spring and Hibernate integration is one of the most-demanded topic which most programmers are looking for and are facing with. Spring is the leading enterprise application framework, and Hibernate is the leading ORM framework so combination of these two guys would be a preferable choice in order to develop robust enterprise applications.

This is a step-by-step tutorial that helps you build a Spring-Hibernate application easily in a clear and concise way. In this first part, we demonstrate how to code a simple Spring MVC application that displays a list of users from MySQL database. The DAO implementation uses Hibernate’s SessionFactory to query against the database, instead of using JdbcTemplate.

The following configuration approaches are used in the demo application:

• Spring MVC: Annotations for controller and XML for bean definitions.
• Hibernate: XML mapping for model class.
• Web Application: using web.xml deployment descriptor file.

The following technologies and pieces of software are used throughout this tutorial:

• Java 7
• Spring framework 4.0.3.RELEASED
• Hibernate ORM 4.3.5.Final
• Spring Tool Suite IDE 3.5.1
• Maven 3
• Tomcat 7

 

 

1.    How Spring supports Hibernate Integration

Basically, in order to support Hibernate integration, Spring provides two key beans available in theorg.springframework.orm.hibernate4 package:

• LocalSessionFactoryBean: creates a Hibernate’s SessionFactory which is injected into Hibernate-based DAO classes.
• HibernateTransactionManager: provides transaction support code for a SessionFactory. Programmers can use @Transactional annotation in DAO methods to avoid writing boiler-plate transaction code explicitly.

Let’s see how these concepts are implemented in a real project.

2.    Setting up Project

Let’s create a Spring MVC project using Spring Tool Suite IDE (See example: Spring MVC beginner tutorial with Spring Tool Suite IDE), name it as SpringMvcHibernateXML.

Setting up Database

Execute the following MySQL script in order to create a database named usersdb with a table named users:

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create database usersdb;

 

CREATE TABLE `users` (

  `user_id` int(11) NOT NULL AUTO_INCREMENT,

  `username` varchar(45) NOT NULL,

  `password` varchar(45) NOT NULL,

  `email` varchar(45) NOT NULL,

  PRIMARY KEY (`user_id`)

) ENGINE=InnoDB AUTO_INCREMENT=16 DEFAULT CHARSET=latin1

Remember to insert some dummy data for testing purspose.

Project Structure

The following screenshot shows final structure of the project:

NOTE: After completing this tutorial, you will create a project structure looks like the above.

Maven Dependencies

Declare versions for Java and Spring framework:

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<properties>

    <java-version>1.7</java-version>

    <org.springframework-version>4.0.3.RELEASE</org.springframework-version>

</properties>

Update pom.xml file for the following dependencies:

• Spring framework dependencies:
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  <dependency>

      <groupId>org.springframework</groupId>

      <artifactId>spring-context</artifactId>

      <version>${org.springframework-version}</version>

  </dependency>

   

  <dependency>

      <groupId>org.springframework</groupId>

      <artifactId>spring-webmvc</artifactId>

      <version>${org.springframework-version}</version>

  </dependency>

  <dependency>

      <groupId>org.springframework</groupId>

      <artifactId>spring-orm</artifactId>

      <version>${org.springframework-version}</version>

      <type>jar</type>

      <scope>compile</scope>

  </dependency>
• Hibernate ORM framework dependencies:
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  <dependency>

      <groupId>org.hibernate</groupId>

      <artifactId>hibernate-core</artifactId>

      <version>4.3.5.Final</version>

  </dependency>
• Java Servlet and JSP dependencies (for compilation only):
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  <dependency>

      <groupId>javax.servlet</groupId>

      <artifactId>javax.servlet-api</artifactId>

      <version>3.1.0</version>

      <scope>provided</scope>

  </dependency>

  <dependency>

      <groupId>javax.servlet.jsp</groupId>

      <artifactId>javax.servlet.jsp-api</artifactId>

      <version>2.3.1</version>

      <scope>provided</scope>

  </dependency>
• JSTL dependency:
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  <dependency>

      <groupId>jstl</groupId>

      <artifactId>jstl</artifactId>

      <version>1.2</version>

  </dependency>
• Apache Commons DBCP dependency (for database connection pooling):
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  <dependency>

      <groupId>org.apache.commons</groupId>

      <artifactId>commons-dbcp2</artifactId>

      <version>2.0</version>

  </dependency>
• MySQL Connector Java dependency (JDBC driver for MySQL):
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  <dependency>

      <groupId>mysql</groupId>

      <artifactId>mysql-connector-java</artifactId>

      <version>5.1.30</version>

  </dependency>
   

NOTE: You can see the whole content of pom.xml file in the attached project.

 

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3.    Coding Model Class Configuring Hibernate Mapping

Writing Model Class

Create a new class named User.java in the package net.codejava.spring.model with the following source code:

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packagenet.codejava.spring.model;

 

publicclass User {

    privateint id;

    privateString username;

    privateString password;

    privateString email;

 

    // getters and setters are removed for brevity

 

}

This model class is used to map the table users and the database to a plain-old Java object (POJO).

Creating Hibernate XML Mapping for the Model Class

We need to create a Hibernate XML mapping file to map the User class to the users table in database. Create aUser.hbm.xml file under the same package as the User class with the following XML code:

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<?xmlversion="1.0"encoding="UTF-8"?>

<!DOCTYPE hibernate-mapping PUBLIC

        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mappingpackage="net.codejava.spring.model">

    <classname="User"table="USERS">

        <idname="id"column="USER_ID">

            <generatorclass="native"/>

        </id>

        <propertyname="username"column="USERNAME"/>

        <propertyname="password"column="PASSWORD"/>

        <propertyname="email"column="EMAIL"/>

    </class> 

</hibernate-mapping>

NOTE: For more information about Hibernate XML mapping, see: Hibernate One-to-Many XML Mapping Example.

Creating Hibernate XML Configuration File

Create hibernate.cfg.xml file under the root of classpath (right in src directory in the project) with the following XML code:

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<?xmlversion='1.0'encoding='utf-8'?>

<!DOCTYPE hibernate-configuration PUBLIC

        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"

        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>       

  <session-factory>

    <propertyname="dialect">org.hibernate.dialect.MySQLDialect</property>

    <propertyname="show_sql">true</property> 

    <mappingresource="net/codejava/spring/model/User.hbm.xml"/>

  </session-factory>

</hibernate-configuration>

This Hibernate configuration file declares which resources need to be mapped (the User.hbm.xml file in this case).

4.    Coding DAO Classes

Writing UserDAO interface

Create a very simple DAO interface for the User class as the following UserDAO.java class:

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packagenet.codejava.spring.dao;

 

importjava.util.List;

 

importnet.codejava.spring.model.User;

 

publicinterface UserDAO {

    publicList<User> list();

}

This interface declares only one method list() that retrieves all users from the database.

Writing UserDAO implementation

Here’s we code an implementation of the UserDAO interface, the UserDAOImpl class as follows:

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packagenet.codejava.spring.dao;

 

importjava.util.List;

 

importnet.codejava.spring.model.User;

 

importorg.hibernate.Criteria;

importorg.hibernate.SessionFactory;

importorg.springframework.transaction.annotation.Transactional;

 

publicclass UserDAOImpl implementsUserDAO {

    privateSessionFactory sessionFactory;

 

    publicUserDAOImpl(SessionFactory sessionFactory) {

        this.sessionFactory = sessionFactory;

    }

 

    @Override

    @Transactional

    publicList<User> list() {

        @SuppressWarnings("unchecked")

        List<User> listUser = (List<User>) sessionFactory.getCurrentSession()

                .createCriteria(User.class)

                .setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY).list();

 

        returnlistUser;

    }

 

}

Notice in this class, a Hibernate’s SessionFactory object is injected via constructor by Spring. The list() method simply obtains the current session from the SessionFactory and queries for a list of all users in the database.

Pay attention to the @Transactional annotation provided by Spring - when a method is annotated by this annotation, Spring will inject transaction support code into the method - thus we don’t have two write any code to handle transaction explicitly.

 

5.    Configuring Spring Application Context

Now, we come to the most important part that wires Spring and Hibernate together through some XML configuration. Open the servlet-context.xml file under src/main/webapp/WEB-INF/spring/appServlet and update its content as follows.

Configuring Spring MVC View Resolvers

As usual, add the following declarations for Spring MVC annotation driven approach:

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<mvc:annotation-driven/>

<mvc:resourcesmapping="/resources/**"location="/resources/"/>

<context:component-scanbase-package="net.codejava.spring"/>

The following declaration for a common view resolver that converts logical view names to actual JSP pages:

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<beanclass="org.springframework.web.servlet.view.InternalResourceViewResolver">

    <propertyname="prefix"value="/WEB-INF/views/"/>

    <propertyname="suffix"value=".jsp"/>

</bean>

Configuring DataSource Bean

We use Apache Commons DBCP for a data source with connection pooling capability:

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<beanid="dataSource"class="org.apache.commons.dbcp2.BasicDataSource"destroy-method="close">

    <propertyname="driverClassName"value="com.mysql.jdbc.Driver"/>

    <propertyname="url"value="jdbc:mysql://localhost:3306/usersdb"/>

    <propertyname="username"value="root"/>

    <propertyname="password"value="secret"/>

</bean>

NOTE: Change database URL, username and password according to values in your environment. This data source will be injected to a SessionFactory bean below.

Configuring SessionFactory Bean

Spring 4 provides support for Hibernate 4’s SessionFactory through a LocalSessionFactoryBean which is actually aFactoryBean that creates a Hibernate’s SessionFactory which is then injected to Hibernate-based DAO beans. Here’s the bean declaration:

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<beanid="sessionFactory"

    class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">

    <propertyname="dataSource"ref="dataSource"/>

    <propertyname="configLocation"value="classpath:hibernate.cfg.xml"/>

</bean>

Note that this LocalSessionFactoryBean requires a DataSource bean which is declared previously. TheconfigLocation property specifies where Hibernate configuration file will be searched for. In this case, it is thehibernate.cfg.xml file in the classpath.

Configuring TransactionManager Bean

The following declaration is for automatic transaction support for the SessionFactory:

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<tx:annotation-driven/>

<beanid="transactionManager"

    class="org.springframework.orm.hibernate4.HibernateTransactionManager">

    <propertyname="sessionFactory"ref="sessionFactory"/>

</bean>

As mentioned in the UserDAOImpl class, we can specify transaction support by using the @Transactional annotation for transaction-aware methods.

Configuring DAO Bean

And finally, configuration for our UserDAOImpl bean - pretty simple:

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<beanid="userDao"class="net.codejava.spring.dao.UserDAOImpl">

    <constructor-arg>

        <refbean="sessionFactory"/>

    </constructor-arg>

</bean>

This bean will be then injected to a Spring MVC controller class which is described below.

NOTE: For the whole content of Spring application context configuration file, see the corresponding file in the attached project.

 

6.    Coding Controller Classes

Write our Spring MVC controller class (HomeController.java) under the net.codejava.spring package with the following code:

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packagenet.codejava.spring;

 

importjava.util.List;

 

importnet.codejava.spring.dao.UserDAO;

importnet.codejava.spring.model.User;

 

importorg.springframework.beans.factory.annotation.Autowired;

importorg.springframework.stereotype.Controller;

importorg.springframework.web.bind.annotation.RequestMapping;

importorg.springframework.web.servlet.ModelAndView;

 

/**

 * Handles requests for the application home page.

 */

@Controller

publicclass HomeController {

     

    @Autowired

    privateUserDAO userDao;

     

    @RequestMapping(value="/")

    publicModelAndView home() {

        List<User> listUsers = userDao.list();

        ModelAndView model = newModelAndView("home");

        model.addObject("userList", listUsers);

        returnmodel;

    }

     

}

Here, an implementation of the UserDAO is injected automatically by Spring (because @Autowired annotation is used). Remember the UserDAOImpl bean we declared in the Spring application context configuration file previously? It is injected to this controller automatically so that the handling method home() can use it to list all users from the database. And eventually, the home() method returns a view named home which is resolved an actual JSP page which is described below.

7.    Coding View Page

Create a home.jsp under the src/main/webapp/WEB-INF/views directory with the following content:

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<%@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">

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>

 

<html>

    <head>

        <metahttp-equiv="Content-Type"content="text/html; charset=UTF-8">

        <title>Home</title>

    </head>

    <body>

        <divalign="center">

            <h1>Contact List</h1>

            <tableborder="1">

                <th>No</th>

                <th>Username</th>

                <th>Email</th>

                 

                <c:forEachvar="user"items="${userList}"varStatus="status">

                <tr>

                    <td>${status.index + 1}</td>

                    <td>${user.username}</td>

                    <td>${user.email}</td>

                             

                </tr>

                </c:forEach>             

            </table>

        </div>

    </body>

</html>

This JSP page simply displays a list of users which is passed by the controller, by using JSTL tags.

 

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8.    Testing the Application

Deploy the SpringMvcHibernateXML application on Tomcat server and access its default page via the following URL:

http://localhost:8080/SpringMvcHibernateXML

If everything is going fine, you would see the following result:

Congratulations! You have completed our first part of Spring-Hibernate Integration series. You can download the attached project and experiment yourself. A deployable WAR file is also provided for your convenience.