SpringData jpa入门案例-知识点

学习SpringData Jpa可以简化持久层dao的操作，目前我们常使用的是查询语句，使用了注解@Query

该注解存在两个参数：

nativeQuery：是否执行本地查询，即sql语句；默认值为false，即执行jpql语句

value：执行语句

那么，知道了查询之后，对于增删改而言，它需要多添加一个注解@Modifying

//执行更新语句
	@Query(value="update Standard set name=? where id=?")
	@Modifying
	public void update(String name,int id);

但是，进行Junit测试时，会报错：

org.springframework.dao.InvalidDataAccessApiUsageException: Executing an update/delete query; nested exception is javax.persistence.TransactionRequiredException: Executing an update/delete query
  at org.springframework.orm.jpa.EntityManagerFactoryUtils.convertJpaAccessExceptionIfPossible(EntityManagerFactoryUtils.java:413)
  at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:227)
  at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.translateExceptionIfPossible(AbstractEntityManagerFactoryBean.java:417)
  at org.springframework.dao.support.ChainedPersistenceExceptionTranslator.translateExceptionIfPossible(ChainedPersistenceExceptionTranslator.java:59)
  at org.springframework.dao.support.DataAccessUtils.translateIfNecessary(DataAccessUtils.java:213)
  at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:147)
  at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
  at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:133)
  at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
  at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
  at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
  at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:208)
  at com.sun.proxy.$Proxy40.update(Unknown Source)
  at cn.itcast.bos.dao.base.StandardDaoTest.testFindByName2(StandardDaoTest.java:26)
  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:606)
  at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
  at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
  at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
  at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
  at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
  at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
  at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
  at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
  at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:254)
  at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:89)
  at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
  at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
  at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
  at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
  at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
  at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
  at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
  at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
  at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:193)
  at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
  at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
  at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
  at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)
  at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
  at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
Caused by: javax.persistence.TransactionRequiredException: Executing an update/delete query
  at org.hibernate.jpa.spi.AbstractQueryImpl.executeUpdate(AbstractQueryImpl.java:54)
  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:606)
  at org.springframework.orm.jpa.SharedEntityManagerCreator$DeferredQueryInvocationHandler.invoke(SharedEntityManagerCreator.java:364)
  at com.sun.proxy.$Proxy42.executeUpdate(Unknown Source)
  at org.springframework.data.jpa.repository.query.JpaQueryExecution$ModifyingExecution.doExecute(JpaQueryExecution.java:242)
  at org.springframework.data.jpa.repository.query.JpaQueryExecution.execute(JpaQueryExecution.java:82)
  at org.springframework.data.jpa.repository.query.AbstractJpaQuery.doExecute(AbstractJpaQuery.java:114)
  at org.springframework.data.jpa.repository.query.AbstractJpaQuery.execute(AbstractJpaQuery.java:104)
  at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:482)
  at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:460)
  at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
  at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
  at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:281)
  at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
  at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
  at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:136)
	... 37 more

javax.persistence.TransactionRequiredException: Executing an update/delete query

这表明：项目中缺少事务配置管理。但是我们目前只是进行了一个小小的入门demo，所以不想很快往前赶的同学，这一点可以忽略。

解决方案：

1、在 Spring 核心配置文件里引入在业务层的事务管理器（这一步我们之前已经做了）

<context:component-scan base-package="com.liwei.springdata.service"></context:component-scan>

2、写好 Service 类的相关方法，在事务方法前面加上 @Transactional 注解。

@Service
public class PersonService {

    @Autowired
    private PersonRepository personRepository;

    @Transactional
    public void updateEmailByLastName(String lastName,String email){
        personRepository.updatePersonEmailByLastName(lastName, email);
    }
}

经过测试代码的运行，控制台就可以输出更新语句。

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext.xml")
public class StandardDaoTest {
	
	@Autowired
	private StandardDao standardDao;
	
	@Test
	public void testFindByName2() {
		//List<Standard> list = standardDao.findByAbc("标准二(0-200公斤)");
		//List<Standard> list2 = standardDao.findByXyz("标准二(0-200公斤)");
		standardDao.update("标准三(0-300公斤)",1);
		//	System.out.println(list);
		//System.out.println(list2);
	}
}

总结：
（1）可以通过自定义的 JPQL 完成 UPDATE 和 DELETE 操作。注意： JPQL 不支持使用 INSERT；
（2）在 @Query 注解中编写 JPQL 语句，但必须使用 @Modifying 进行修饰. 以通知 SpringData，这是一个 UPDATE 或 DELETE 操作
（3）UPDATE 或 DELETE 操作需要使用事务，此时需要定义 Service 层，在 Service 层的方法上添加事务操作；
（4）默认情况下， SpringData 的每个方法上有事务，但都是一个只读事务。他们不能完成修改操作。

SpringData jpa入门案例-知识点

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