This post describes a simple Spring JpaRepository example using an in memory HSQL database. The code example is available from GitHub in the Spring-JpaRepository directory. It is based on the Spring-MVC-With-Annotations example and information available here.

JPA Repository

We implement a dummy bean for this example:
 
 
 

@Entity
@AutoProperty
public class SomeItem {

 @Id
 @GeneratedValue(strategy=GenerationType.AUTO)
 private long Id;

 private String someText;

 /* ...Setters & Getters */

}

and the corresponding JpaRepository:

@Transactional
public interface SomeItemRepository
 extends JpaRepository<SomeItem, Long> {

}

Service & Controller

Next, we implement a service where our repository will be injected. We also populate the repository with dummy data:

@Service
@Repository
public class SomeItemService {

 @Autowired
 private SomeItemRepository someItemRepository;

 @PostConstruct
 @Transactional
 public void populate() {

 SomeItem si = new SomeItem();
 si.setSomeText("aaa");
 someItemRepository.saveAndFlush(si);

 si = new SomeItem();
 si.setSomeText("bbb");
 someItemRepository.saveAndFlush(si);

 si = new SomeItem();
 si.setSomeText("ccc");
 someItemRepository.saveAndFlush(si);

 }

 @Transactional(readOnly=true)
 public List<SomeItem> getAll() {

 return someItemRepository.findAll();

 }

 @SuppressWarnings("AssignmentToMethodParameter")
 @Transactional
 public SomeItem saveAndFlush(SomeItem si) {

 if ( si != null ) {
 si = someItemRepository.saveAndFlush(si);
 }

 return si;

 }

 @Transactional
 public void delete(long id) {

 someItemRepository.delete(id);

 }

}

and a controller:

@Controller
public class MyController {

 @Autowired
 private SomeItemService someItemService;

 @RequestMapping(value = "/")
 public ModelAndView index() {

 ModelAndView result = new ModelAndView("index");
 result.addObject("items", this.someItemService.getAll());

 return result;

 }

 @RequestMapping(value = "/delete/{id}")
 public String delete(
 @PathVariable(value="id") String id) {

 this.someItemService.delete(Long.parseLong(id));

 return "redirect:/";

 }

 @RequestMapping(value = "/create")
 @SuppressWarnings("AssignmentToMethodParameter")
 public String add() {

 SomeItem si = new SomeItem();
 si.setSomeText("Time is: " + System.currentTimeMillis());

 this.someItemService.saveAndFlush(si);

 return "redirect:/";

 }

}

JPA Configuration

On top of creating an entity manager based on an in-memeory instance of HSQL database, we enable JPA repositories with the
@EnableJpaRepositories annotation:

@Configuration
@EnableJpaRepositories(basePackages={"com.jverstry"})
@EnableTransactionManagement
public class JpaConfig implements DisposableBean {

 private EmbeddedDatabase ed;

 @Bean(name="hsqlInMemory")
 public EmbeddedDatabase hsqlInMemory() {

 if ( this.ed == null ) {
 EmbeddedDatabaseBuilder builder = new EmbeddedDatabaseBuilder();
 this.ed = builder.setType(EmbeddedDatabaseType.HSQL).build();
 }

 return this.ed;

 }

 @Bean
 public LocalContainerEntityManagerFactoryBean entityManagerFactory(){

 LocalContainerEntityManagerFactoryBean lcemfb
 = new LocalContainerEntityManagerFactoryBean();

 lcemfb.setDataSource(this.hsqlInMemory());
 lcemfb.setPackagesToScan(new String[] {"com.jverstry"});

 lcemfb.setPersistenceUnitName("MyPU");

 HibernateJpaVendorAdapter va = new HibernateJpaVendorAdapter();
 lcemfb.setJpaVendorAdapter(va);

 Properties ps = new Properties();
 ps.put("hibernate.dialect", "org.hibernate.dialect.HSQLDialect");
 ps.put("hibernate.hbm2ddl.auto", "create");
 lcemfb.setJpaProperties(ps);

 lcemfb.afterPropertiesSet();

 return lcemfb;

 }

 @Bean
 public PlatformTransactionManager transactionManager(){

 JpaTransactionManager tm = new JpaTransactionManager();

 tm.setEntityManagerFactory(
 this.entityManagerFactory().getObject() );

 return tm;

 }

 @Bean
 public PersistenceExceptionTranslationPostProcessor exceptionTranslation(){
 return new PersistenceExceptionTranslationPostProcessor();
 }

 @Override
 public void destroy() {

 if ( this.ed != null ) {
 this.ed.shutdown();
 }

 }

}

The JSP Page

We create a simple page to list existing items with a delete link, and the possibility to create new items:

👁 Image

 Running The Example

One can run it using the maven tomcat:run goal. Then, browse: http://localhost:9191/spring-jparepository/