Spring ORM example – JPA, Hibernate, Transaction

Filed Under: Spring

Welcome to the Spring ORM Example Tutorial. Today we will look into Spring ORM example using Hibernate JPA transaction management. I will show you a very simple example of Spring standalone application with following features.

  • Dependency Injection (@Autowired annotation)
  • JPA EntityManager (provided by Hibernate)
  • Annotated transactional methods (@Transactional annotation)

Spring ORM Example

spring orm example, spring orm, spring jpa hibernate example, spring hibernate transaction management, spring hibernate jpa

I have used in-memory database for Spring ORM example, so no need for any database setup (but you can change it to any other database in the spring.xml datasource section). This is a Spring ORM standalone application to minimize all dependencies (but you can easily change it to a web project by configuration if you get familiar with spring).

NOTE: For Spring AOP based Transactional (without @Transactional annotation) method resolution approach please check this tutorial: Spring ORM AOP Transaction Management.

Below image shows our final Spring ORM example project.

Spring ORM, Spring ORM Example, Spring ORM JPA Hibernate

Let’s go through each of the Spring ORM example project components one by one.

Spring ORM Maven dependencies

Below is our final pom.xml file having Spring ORM dependencies. We have used Spring 4 and Hibernate 4 in our Spring ORM example.


<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<groupId>hu.daniel.hari.learn.spring</groupId>
	<artifactId>Tutorial-SpringORMwithTX</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<properties>
		<!-- Generic properties -->
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<java.version>1.7</java.version>

		<!-- SPRING & HIBERNATE / JPA -->
		<spring.version>4.0.0.RELEASE</spring.version>
		<hibernate.version>4.1.9.Final</hibernate.version>

	</properties>

	<dependencies>
		<!-- LOG -->
		<dependency>
			<groupId>log4j</groupId>
			<artifactId>log4j</artifactId>
			<version>1.2.17</version>
		</dependency>

		<!-- Spring -->
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-context</artifactId>
			<version>${spring.version}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-orm</artifactId>
			<version>${spring.version}</version>
		</dependency>

		<!-- JPA Vendor -->
		<dependency>
			<groupId>org.hibernate</groupId>
			<artifactId>hibernate-entitymanager</artifactId>
			<version>${hibernate.version}</version>
		</dependency>

		<!-- IN MEMORY Database and JDBC Driver -->
		<dependency>
			<groupId>hsqldb</groupId>
			<artifactId>hsqldb</artifactId>
			<version>1.8.0.7</version>
		</dependency>

	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.1</version>
				<configuration>
					<source>${java.version}</source>
					<target>${java.version}</target>
				</configuration>
			</plugin>
		</plugins>
	</build>

</project>
  • We need spring-context and spring-orm as Spring dependencies.
  • We use hibernate-entitymanager for Hibernate as JPA implementation. hibernate-entitymanager is dependent on hibernate-core this why we don’t have to put hibernate-core in pom.xml explicitly. It’s being pulled into our project through maven transitive dependencies.
  • We also need JDBC driver as dependency for database access. We are using HSQLDB that contains the JDBC driver and a working in memory database.

Spring ORM Model Class

We can use standard JPA annotations for mapping in our model beans because Hibernate provides JPA implementation.


package hu.daniel.hari.learn.spring.orm.model;

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

@Entity
public class Product {

	@Id
	private Integer id;
	private String name;

	public Product() {
	}

	public Product(Integer id, String name) {
		this.id = id;
		this.name = name;
	}
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}

	@Override
	public String toString() {
		return "Product [id=" + id + ", name=" + name + "]";
	}

}

We use @Entity and @Id JPA annotations to qualify our POJO as an Entity and to define it’s primary key.

Spring ORM DAO Class

We create a very simple DAO class that provides persist and findALL methods.


package hu.daniel.hari.learn.spring.orm.dao;

import hu.daniel.hari.learn.spring.orm.model.Product;

import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

import org.springframework.stereotype.Component;

@Component
public class ProductDao {

	@PersistenceContext
	private EntityManager em;

	public void persist(Product product) {
		em.persist(product);
	}

	public List<Product> findAll() {
		return em.createQuery("SELECT p FROM Product p").getResultList();
	}

}
  • @Component is Spring annotation that tell the Spring container that we can use this class through Spring IoC (Dependency Injection).
  • We use JPA @PersistenceContext annotation that indicate dependency injection to an EntityManager. Spring injects a proper instance of EntityManager according to the spring.xml configuration.

Spring ORM Service Class

Our simple service class has 2 write and 1 read methods – add, addAll and listAll.


package hu.daniel.hari.learn.spring.orm.service;

import hu.daniel.hari.learn.spring.orm.dao.ProductDao;
import hu.daniel.hari.learn.spring.orm.model.Product;

import java.util.Collection;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.transaction.annotation.Transactional;

@Component
public class ProductService {

	@Autowired
	private ProductDao productDao;

	@Transactional
	public void add(Product product) {
		productDao.persist(product);
	}
	
	@Transactional
	public void addAll(Collection<Product> products) {
		for (Product product : products) {
			productDao.persist(product);
		}
	}

	@Transactional(readOnly = true)
	public List<Product> listAll() {
		return productDao.findAll();

	}

}
  • We use Spring @Autowired annotation to inject ProductDao in our service class.
  • We want to use transaction management, so methods are annotated with @Transactional Spring annotation. The listAll method only reads the database so we set the @Transactional annotation to read-only for optimisation.

Spring ORM Example Bean Configuration XML

Our spring ORM example project java classes are ready, let’s look at our spring bean configuration file now.

spring.xml


<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" 
	xmlns:p="http://www.springframework.org/schema/p"
	xmlns:context="http://www.springframework.org/schema/context" 
	xmlns:tx="http://www.springframework.org/schema/tx" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="
		http://www.springframework.org/schema/beans
		http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
		http://www.springframework.org/schema/context
		http://www.springframework.org/schema/context/spring-context-3.0.xsd
		http://www.springframework.org/schema/tx
		http://www.springframework.org/schema/tx/spring-tx.xsd
		">
	
	<!-- Scans the classpath for annotated components that will be auto-registered as Spring beans -->
	<context:component-scan base-package="hu.daniel.hari.learn.spring" />
	<!-- Activates various annotations to be detected in bean classes e.g: @Autowired -->
	<context:annotation-config />

	<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
		<property name="driverClassName" value="org.hsqldb.jdbcDriver" />
		<property name="url" value="jdbc:hsqldb:mem://productDb" />
		<property name="username" value="sa" />
		<property name="password" value="" />
	</bean>
	
	<bean id="entityManagerFactory" 
			class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"
			p:packagesToScan="hu.daniel.hari.learn.spring.orm.model"
            p:dataSource-ref="dataSource"
			>
		<property name="jpaVendorAdapter">
			<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
				<property name="generateDdl" value="true" />
				<property name="showSql" value="true" />
			</bean>
		</property>
	</bean>

	<!-- Transactions -->
	<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
		<property name="entityManagerFactory" ref="entityManagerFactory" />
	</bean>
	<!-- enable the configuration of transactional behavior based on annotations -->
	<tx:annotation-driven transaction-manager="transactionManager" />

</beans>
  1. First we tell spring that we want to use classpath scanning for Spring components (Services, DAOs) rather than defining them one by one in spring xml. We have also enabled Spring annotation detection.
  2. Adding the datasource, that is currently HSQLDB in-memory database.
  3. We set up a JPA EntityManagerFactory that will used by the application to obtain an EntityManager. Spring supports 3 different ways to do this, we have used LocalContainerEntityManagerFactoryBean for full JPA capabilities.

    We set LocalContainerEntityManagerFactoryBean attributes as:

    1. packagesToScan attribute that points to our model classes package.
    2. datasource defined earlier in spring configuration file.
    3. jpaVendorAdapter as Hibernate and setting some hibernate properties.
  4. We create Spring PlatformTransactionManager instance as a JpaTransactionManager. This transaction manager is appropriate for applications that use a single JPA EntityManagerFactory for transactional data access.
  5. We enable the configuration of transactional behavior based on annotations, and we set the transactionManager we created.

Spring ORM Hibernate JPA Example Test Program

Our spring ORM JPA Hibernate example project is ready, so let’s write a test program for our application.


public class SpringOrmMain {
	
	public static void main(String[] args) {
		
		//Create Spring application context
		ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("classpath:/spring.xml");
		
		//Get service from context. (service's dependency (ProductDAO) is autowired in ProductService)
		ProductService productService = ctx.getBean(ProductService.class);
		
		//Do some data operation
		
		productService.add(new Product(1, "Bulb"));
		productService.add(new Product(2, "Dijone mustard"));
		
		System.out.println("listAll: " + productService.listAll());
		
		//Test transaction rollback (duplicated key)
		
		try {
			productService.addAll(Arrays.asList(new Product(3, "Book"), new Product(4, "Soap"), new Product(1, "Computer")));
		} catch (DataAccessException dataAccessException) {
		}
		
		//Test element list after rollback
		System.out.println("listAll: " + productService.listAll());
		
		ctx.close();
		
	}
}

You can see how easily we can start the Spring container from a main method. We are getting our first dependency injected entry point, the service class instance. ProductDao class reference injected to the ProductService class after the spring context is initialized.

After we got ProducService instance, we can test it’s methods, all method call will be transactional due to Spring’s proxy mechanism. We also test rollback in this example.

If you run above spring ORM example test program, you will get below logs.


Hibernate: insert into Product (name, id) values (?, ?)
Hibernate: insert into Product (name, id) values (?, ?)
Hibernate: select product0_.id as id0_, product0_.name as name0_ from Product product0_
listAll: [Product [id=1, name=Bulb], Product [id=2, name=Dijone mustard]]
Hibernate: insert into Product (name, id) values (?, ?)
Hibernate: insert into Product (name, id) values (?, ?)
Hibernate: insert into Product (name, id) values (?, ?)
Hibernate: select product0_.id as id0_, product0_.name as name0_ from Product product0_
listAll: [Product [id=1, name=Bulb], Product [id=2, name=Dijone mustard]]

Note that the second transaction is rolled back, this why product list didn’t changed.

If you use log4j.properties file from attached source, you can see what’s going on under the hood.

References:
http://docs.spring.io/spring/docs/current/spring-framework-reference/html/orm.html

You can download the final Spring ORM JPA Hibernate Example project from below link and play around with it to learn more.

Comments

  1. gs says:

    Exception in thread “main” java.lang.IllegalArgumentException: Unknown entity: hu.daniel.hari.learn.spring.orm.spring.orm.model.Product

    How to resolve it

    1. Dnyaneshwar says:

      you have to import that class in your file. Simply add it or if u are working on eclipse then its so simple.

  2. Uday says:

    If you encounter the below issue,
    No bean named ‘transactionManager’ is defined

    simply add the bean value next to transaction annotation

    @Transactional(value = “transactionManager”)
    public void add(Product product) {
    productDao.persist(product);
    }

    You can also declare the @Transactional annotation at class leve

  3. yggdras says:

    Followed your spring.xml config but I get this error:

    org.springframework.beans.factory.BeanCreationException: Error creating bean with name ‘entityManagerFactory’: Failed to introspect bean class [org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean] for lookup method metadata: could not find class that it depends on; nested exception is java.lang.NoClassDefFoundError: javax/persistence/SharedCacheMode

    maybe it’s because of this line here where I get an error

    ref=”entityManagerFactory” is red and the error : or delimiter expected, got ‘entityManagerFactory’

    1. yggdras says:

      some of the text got messed up so here is the screen cap

      https://pasteboard.co/GKjLUBO.png

  4. Hassan says:

    Please mention where to add dialect for hibernate …. I wonder how your application is working without specifying dialect…

  5. sai says:

    NICE ONE.
    if we have an association, it will be different
    let me take a example in your Product Class let say we have set Of customers
    ——————————-
    @Entity
    public class Product {

    @Id
    private Integer id;
    private String name;
    @OneToMany(fetch type LAZY)
    set cust= new HashSet(0);
    // set and get

    }
    WE HAVE DAO METHOD LIKE THIS

    PUBLIC Set getCustomerstBasedOnProductId(Inetger id){
    Product pr=entityManger.get(1);//it will return ProductObject
    Set cuts=pr.getCustomers();// it will return set of Customers
    for(Customers c : cuts){

    Sop(c.getProductName());// here we will getException saying that “Exception in thread “main” org.hibernate.LazyInitializationException: ”
    }

    }

    Exception:
    why bcoz after execution of get() method Session object will be closed so proxy Object will be deleted from the Session so that we will get this kind of exception …
    how can i resolve this problem
    please help me

  6. Simron says:

    Since you defined @PersistenceContext in ProductDao, every method will be there own transaction.
    So why to define @Transactional on method of ProductService ?

  7. Rodrigo Marini says:

    Exception in thread “main” java.lang.NoClassDefFoundError: antlr/RecognitionException

    This lib is into hibernate .jar, but the application don’t recognizes…

    1. Me says:

      Same problem 🙁

  8. Carlos says:

    Excellent. In which directory I should create the spring.xml file?

  9. Mithilesh says:

    Exception in thread “main” javax.persistence.TransactionRequiredException: No EntityManager with actual transaction available for current thread – cannot reliably process ‘persist’ call
    at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:278)
    at com.sun.proxy.$Proxy8.persist(Unknown Source)
    at com.dao.ProductDao.Persist(ProductDao.java:19)
    at com.service.ProductService.add(ProductService.java:19)
    at SpringOrmMain.main(SpringOrmMain.java:22)

    1. stef says:

      Same problem. I’m using MySQL.

  10. Pankaj says:

    Thanks Daniel,
    This article was very useful.

  11. ismail says:

    Thank you for this example Dániel!

    In main class if we use Autowired annotation for ProductService productService does it work? Or if we move ProductService to another class which will be created after this line executed: ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext(“classpath:/spring.xml”);

    If not, I guess we have to use ctx whenever Spring beans are required. Regards.

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