SpringData修改和删除操作

SpringData的查询我们已经学完了，我们现在就研究一下SpringData的修改和删除。

@Modifying 注解和事务

@Query 与 @Modifying 这两个 annotation一起声明，可定义个性化更新操作，例如只涉及某些字段更新时最为常用，示例如下：
//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
//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
//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.
//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!
```
@Modifying
	@Query("UPDATE Person p SET p.lastName = :lastName WHERE id = :id")
	void updatePersonName(@Param("id") Integer id, @Param("lastName") String lastName);
	
```
　　
注意：方法的返回值应该是 int，表示更新语句所影响的行数在调用的地方必须加事务，没有事务不能正常执行

上面会出现错误，是因为我们没有加入事务出错，错误的信息是：

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:156)
	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.LockModeRepositoryPostProcessor$LockModePopulatingMethodIntercceptor.invoke(LockModeRepositoryPostProcessor.java:92)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
	at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
	at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:207)
	at com.sun.proxy.$Proxy22.updatePersonName(Unknown Source)
	at com.fxr.test.SpringDataTest.testModifyingAnnotation(SpringDataTest.java:67)
	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.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
	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$2.evaluate(ParentRunner.java:229)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
	at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
	at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: javax.persistence.TransactionRequiredException: Executing an update/delete query
	at org.hibernate.ejb.AbstractQueryImpl.executeUpdate(AbstractQueryImpl.java:96)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at org.springframework.orm.jpa.SharedEntityManagerCreator$DeferredQueryInvocationHandler.invoke(SharedEntityManagerCreator.java:328)
	at com.sun.proxy.$Proxy24.executeUpdate(Unknown Source)
	at org.springframework.data.jpa.repository.query.JpaQueryExecution$ModifyingExecution.doExecute(JpaQueryExecution.java:174)
	at org.springframework.data.jpa.repository.query.JpaQueryExecution.execute(JpaQueryExecution.java:61)
	at org.springframework.data.jpa.repository.query.AbstractJpaQuery.doExecute(AbstractJpaQuery.java:95)
	at org.springframework.data.jpa.repository.query.AbstractJpaQuery.execute(AbstractJpaQuery.java:85)
	at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:323)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
	at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:98)
	at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:262)
	at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:95)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
	at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:136)
	... 31 more

解决上述的问题：首先定义一个PersonService类

package com.fxr.springdata;

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

@Service
public class PersonService {

	@Autowired
	private PersonRepsotory personRepsotory;
	
	@Transactional
	public void updataPerson(String lastName,Integer id){
		personRepsotory.updatePersonName(id, lastName);
	}
	
}

　　在Service类上加事务的注解。就解决上述的问题。

事务

Spring Data 提供了默认的事务处理方式，即所有的查询均声明为只读事务。
对于自定义的方法，如需改变 Spring Data 提供的事务默认方式，可以在方法上注解 @Transactional 声明
进行多个 Repository 操作时，也应该使它们在同一个事务中处理，按照分层架构的思想，这部分属于业务逻辑层，因此，需要在 Service 层实现对多个 Repository 的调用，并在相应的方法上声明事务。