這篇文章描述了一個(gè)使用內(nèi)存中HSQL數(shù)據(jù)庫的簡單Spring JpaRepository示例。 該代碼示例可從GitHub的Spring-JpaRepository目錄中獲得。 它基于帶有注釋的Spring-MVC-示例和此處提供的信息 。

JPA資料庫

我們?yōu)樵撌纠龑?shí)現(xiàn)一個(gè)虛擬bean：

@Entity @AutoProperty public class SomeItem {@Id@GeneratedValue(strategy=GenerationType.AUTO)private long Id;private String someText;/* ...Setters & Getters */}

和相應(yīng)的JpaRepository ：

@Transactional public interface SomeItemRepositoryextends JpaRepository<SomeItem, Long> {}

服務(wù)與控制器

接下來，我們實(shí)現(xiàn)一個(gè)將注入我們的存儲庫的服務(wù)。 我們還使用偽數(shù)據(jù)填充存儲庫：

@Service @Repository public class SomeItemService {@Autowiredprivate SomeItemRepository someItemRepository;@PostConstruct@Transactionalpublic 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")@Transactionalpublic SomeItem saveAndFlush(SomeItem si) {if ( si != null ) {si = someItemRepository.saveAndFlush(si);}return si;}@Transactionalpublic void delete(long id) {someItemRepository.delete(id);}}

和一個(gè)控制器：

@Controller public class MyController {@Autowiredprivate 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配置

除了基于HSQL數(shù)據(jù)庫的內(nèi)存實(shí)例創(chuàng)建實(shí)體管理器之外，我們還通過以下方式啟用JPA存儲庫：
@EnableJpaRepositories批注：

@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;}@Beanpublic 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;}@Beanpublic PlatformTransactionManager transactionManager(){JpaTransactionManager tm = new JpaTransactionManager();tm.setEntityManagerFactory(this.entityManagerFactory().getObject() );return tm;}@Beanpublic PersistenceExceptionTranslationPostProcessor exceptionTranslation(){return new PersistenceExceptionTranslationPostProcessor();}@Overridepublic void destroy() {if ( this.ed != null ) {this.ed.shutdown();}}}

JSP頁面

我們創(chuàng)建一個(gè)簡單的頁面來列出具有刪除鏈接的現(xiàn)有項(xiàng)目，以及創(chuàng)建新項(xiàng)目的可能性：

運(yùn)行示例

可以使用maven tomcat：run目標(biāo)運(yùn)行它。 然后，瀏覽：http：// localhost：9191 / spring-jparepository /

參考： Spring JpaRepository示例（內(nèi)存中），來自JCG合作伙伴 Jerome Versrynge，在技術(shù)說明博客中。

翻譯自: https://www.javacodegeeks.com/2013/04/spring-jparepository-example-in-memory.html

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