Spring MVC With JPA

JPA (Java Persistence API) is an API that works as a bridge between Java application and Relational database. It is a set of classes and interfaces that are used to perform database operations efficiently. It reduces the effort of database configuration in Java application and supported by all the major databases MySQL, Oracle, Redhat, etc.

Originally, JPA was released combined with EJB as a business logic layer and can be accessed using javax.ejb.EntityBean Interface. but now various products having the JPA persistence flavor in them such as Hibernate, Spring Data JPA, etc.

In this article, we will learn to use JPA in Spring application and connect with the database(MySQL). The following image shows the structure and file hierarchy of our Maven-based Spring project.

Project Structure

// RegisterController.java

This is our controller class that has two methods index() and save(). The first is used to return a JSP page as a user form and the second is used to save the user details into the database.

package com.studytonight.controllers; 

import javax.validation.Valid;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PostMapping;
import com.studytonight.models.User;
import com.studytonight.service.UserService;

@Controller
public class RegisterController{

	@Autowired 
	private UserService userService;
	
	@GetMapping("/")
	public String index() {
		return "register";
	}
	
	@PostMapping("save")
	public String save(@Valid @ModelAttribute User user, BindingResult result) {
		if(result.hasErrors()) {
			return "register";
		}else {
			 userService.register(user);
			 return "successful";
		}	
	}	
}

// user.java

This is our entity class that represents the User table structure in the database. We used @Entity annotation to mark it as an Entity. The Spring will create a User table into the MySQL database.

package com.studytonight.models;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity
public class User {

	@Id
	@GeneratedValue
	private Long id;
	private String name;
	private Long mobile;
	public Long getId() {
		return id;
	}
	public void setId(Long id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public Long getMobile() {
		return mobile;
	}
	public void setMobile(Long mobile) {
		this.mobile = mobile;
	}
}

// UserRepository.java

It is an interface for DAO implementation. It contains a single save() method.

package com.studytonight.repository;
import com.studytonight.models.User;
public interface UserRepository {
	User save(User user);
}

// UserRepositoryImpl.java

It is our DAO(Data Access Object) implementation class that performs database operations. In our case, we are inserting user data into table so the persist() method of EntityManager is used.

package com.studytonight.repository;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;
import com.studytonight.models.User;

@Component
@Repository
public class UserRepositoryImpl implements UserRepository{

	@PersistenceContext
	private EntityManager em;
	
	@Override
	@Transactional
	public User save(User user) {
		em.persist(user);
		em.flush();
		return  user;
	}
}

// UserService.java

It is an interface for service class implementation. It contains a single method register().

package com.studytonight.service;
import org.springframework.stereotype.Service;
import com.studytonight.models.User;
public interface UserService {
	User register(User user);
}

// UserServiceImpl.java

It is our service implementation class that called DAO's save() method to save the user data.

package com.studytonight.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import com.studytonight.models.User;
import com.studytonight.repository.UserRepository;

@Component
@Service
public class UserServiceImpl implements UserService {

	@Autowired
	UserRepository userRepository;
	
	@Override
	@Transactional
	public User register(User user) {
		// TODO Auto-generated method stub
		return userRepository.save(user);
	}
}

These XML files are Java persistance API configuration files that contains connection details, database dialects and EntityManagerFactory configuration.

// persistance.xml

<persistence 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"
	version="2.0">
	<persistence-unit name="punit"></persistence-unit>
</persistence>

// jpaContext.xml

<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:context="http://www.springframework.org/schema/context"
	xmlns:tx="http://www.springframework.org/schema/tx"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd">

	<context:annotation-config />
	<context:component-scan
		base-package="com.studytonight"></context:component-scan>

	<bean
		class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" />

	<bean id="datasource"
		class="org.springframework.jdbc.datasource.DriverManagerDataSource">
		<property name="driverClassName"
			value="com.mysql.jdbc.Driver"></property>
		<property name="url"
			value="jdbc:mysql://localhost:3306/springwithdb?autoReconnect=true"></property>
		<property name="username" value="root_user" />
		<property name="password" value="root_password" />
	</bean>

	<bean id="entityManagerFactory"
		class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
		<property name="persistenceUnitName" value="punit" />
		<property name="dataSource" ref="datasource" />
		<property name="jpaVendorAdapter">
			<bean
				class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
				<property name="showSql" value="true" />
			</bean>
		</property>
		<!-- JPA vendor properties: specific to Hibernate, in our case -->
		<property name="jpaPropertyMap">
			<map>
				<entry key="hibernate.dialect"
					value="org.hibernate.dialect.MySQLDialect" />

				<entry key="hibernate.hbm2ddl.auto" value="create"></entry>
				<entry key="hibernate.format_sql" value="true"></entry>
			</map>
		</property>

	</bean>

	<bean id="transactionManager"
		class="org.springframework.orm.jpa.JpaTransactionManager">
		<property name="entityManagerFactory" ref="entityManagerFactory" />
	</bean>
	<tx:annotation-driven />

	<bean id="persistenceExceptionTranslationPostProcessor"
		class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor" />

</beans>

// register.jsp

This is a JSP page that contains an HTML form and renders when the application starts.

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
	pageEncoding="ISO-8859-1"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>User Registration Form</title>
</head>
<body>
	<h2>User Registration Form</h2>
	<form action="save" method="post">
		<label>User Name : </label> <input type="text" name="name"><br>
		<br> <label>Mobile : </label> <input type="text" name="mobile"><br>
		<br> <input type="submit" value="Register">
	</form>
</body>
</html>

// successful.jsp

This JSP page shows a success page when user registers successfuly.

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
	pageEncoding="ISO-8859-1"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title></title>
</head>
<body>
	<h2>Registered Successfully!</h2>
</body>
</html>

// servletConfig.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:context="http://www.springframework.org/schema/context"
	xmlns:mvc="http://www.springframework.org/schema/mvc"
	xsi:schemaLocation="
		http://www.springframework.org/schema/beans
    	http://www.springframework.org/schema/beans/spring-beans.xsd
    	http://www.springframework.org/schema/context
    	http://www.springframework.org/schema/context/spring-context.xsd
    	http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd">

	<!-- Step 3: Add support for component scanning -->
	<context:component-scan base-package="com.studytonight.controllers" />

	<!-- Step 4: Add support for conversion, formatting and validation support -->
	<mvc:annotation-driven/>

	<!-- Step 5: Define Spring MVC view resolver -->
	<bean
		class="org.springframework.web.servlet.view.InternalResourceViewResolver">
		<property name="prefix" value="/WEB-INF/views/" />
		<property name="suffix" value=".jsp" />
	</bean>
</beans>

// web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns="http://java.sun.com/xml/ns/javaee"
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
	version="2.5">
	<display-name>springwithdb</display-name>

	<context-param>
		<param-name>contextConfigLocation</param-name>
		<param-value>classPath:/jpaContext.xml</param-value>
	</context-param>

	<listener>
		<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
	</listener>

	<!-- Spring MVC Configs -->

	<!-- Step 1: Configure Spring MVC Dispatcher Servlet -->
	<servlet>
		<servlet-name>dispatcher</servlet-name>
		<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
		<init-param>
			<param-name>contextConfigLocation</param-name>
			<param-value>/WEB-INF/servlet-config.xml</param-value>
		</init-param>
		<load-on-startup>1</load-on-startup>
	</servlet>

	<!-- Step 2: Set up URL mapping for Spring MVC Dispatcher Servlet -->
	<servlet-mapping>
		<servlet-name>dispatcher</servlet-name>
		<url-pattern>/</url-pattern>
	</servlet-mapping>

</web-app>

pom.xml

This file contains all the dependencies of this project such as spring jars, servlet jars, etc. Put these dependencies into your project to run the application.

<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.studytonight</groupId>
	<artifactId>springwithdb</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>war</packaging>
	<dependencies>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-core</artifactId>
			<version>${spring.version}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-context</artifactId>
			<version>${spring.version}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-webmvc</artifactId>
			<version>${spring.version}</version>
		</dependency>
		<dependency>
			<groupId>org.hibernate.validator</groupId>
			<artifactId>hibernate-validator</artifactId>
			<version>6.1.1.Final</version>
		</dependency>
		<dependency>
			<groupId>com.fasterxml.jackson.core</groupId>
			<artifactId>jackson-databind</artifactId>
			<version>2.10.0.pr3</version>
		</dependency>
		<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>8.0.13</version>
		</dependency>
		<dependency>
			<groupId>org.hibernate</groupId>
			<artifactId>hibernate-core</artifactId>
			<version>4.1.4.Final</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-jdbc</artifactId>
			<version>3.2.0.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-orm</artifactId>
			<version>3.2.0.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>javax.xml.bind</groupId>
			<artifactId>jaxb-api</artifactId>
			<version>2.3.0</version>
		</dependency>
		<dependency> 
			<groupId>org.hibernate</groupId>
			<artifactId>hibernate-entitymanager</artifactId>
			<version>4.1.9.Final</version>
		</dependency>

		<!-- https://mvnrepository.com/artifact/javax.transaction/jta -->
		<dependency>
			<groupId>javax.transaction</groupId>
			<artifactId>jta</artifactId>
			<version>1.1</version>
		</dependency>
	</dependencies>
	<properties>
		<spring.version>5.2.8.RELEASE</spring.version>
	</properties>
	<build>
		<sourceDirectory>src</sourceDirectory>
		<plugins>
			<plugin>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.8.1</version>
				<configuration>
					<source>1.8</source>
					<target>1.8</target>
				</configuration>
			</plugin>
			<plugin>
				<artifactId>maven-war-plugin</artifactId>
				<version>3.2.3</version>
				<configuration>
					<warSourceDirectory>WebContent</warSourceDirectory>
				</configuration>
			</plugin>
		</plugins>
	</build>
</project>

Run the Application

After successfully completing the project and adding the dependencies run the application and you will get the output as below.

When a user is successfully registered then data will be stored in the user table that you can verify by accessing your database.