如何在@Transactional方法中手动强制提交？

Question

我正在使用Spring/Spring-data-JPA,并发现自己需要在单元测试中手动强制提交.我的用例是我正在进行多线程测试,其中我必须使用在生成线程之前持久化的数据.

不幸的是,鉴于测试在一个@Transactional事务中运行,即使是一个flush也没有让它可以被生成的线程访问.

   @Transactional   
   public void testAddAttachment() throws Exception{
        final Contract c1 = contractDOD.getNewTransientContract(15);
        contractRepository.save(c1);

        // Need to commit the saveContract here, but don't know how!                
        em.getTransaction().commit();

        List<Thread> threads = new ArrayList<>();
        for( int i = 0; i < 5; i++){
            final int threadNumber = i; 
            Thread t =  new Thread( new Runnable() {
                @Override
                @Transactional
                public void run() {
                    try {
                        // do stuff here with c1

                        // sleep to ensure that the thread is not finished before another thread catches up
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }
            });
            threads.add(t);
            t.start();
        }

        // have to wait for all threads to complete
        for( Thread t : threads )
            t.join();

        // Need to validate test results.  Need to be within a transaction here
        Contract c2 = contractRepository.findOne(c1.getId());
    }

我尝试过使用实体管理器,但是当我这样做时会收到错误消息:

org.springframework.dao.InvalidDataAccessApiUsageException: Not allowed to create transaction on shared EntityManager - use Spring transactions or EJB CMT instead; nested exception is java.lang.IllegalStateException: Not allowed to create transaction on shared EntityManager - use Spring transactions or EJB CMT instead
    at org.springframework.orm.jpa.EntityManagerFactoryUtils.convertJpaAccessExceptionIfPossible(EntityManagerFactoryUtils.java:293)
    at org.springframework.orm.jpa.aspectj.JpaExceptionTranslatorAspect.ajc$afterThrowing$org_springframework_orm_jpa_aspectj_JpaExceptionTranslatorAspect$1$18a1ac9(JpaExceptionTranslatorAspect.aj:33)

有没有办法提交交易并继续下去？我一直无法找到任何允许我拨打电话的方法commit().

Answer 1

在测试hibernate事件监听器时我有一个类似的用例,它只在commit上调用.

解决方案是将代码保存为另一个带注释的方法REQUIRES_NEW.(在另一个类中)这样生成一个新事务,并在方法返回后发出flush/commit.

请记住,这可能会影响所有其他测试!因此,相应地编写它们或者您需要确保在测试运行后可以清理它们.

Answer 2

为什么不使用spring TransactionTemplate来以编程方式控制事务？您还可以重新@Transactional构建代码,以便每个"事务块"都有自己的方法,但鉴于它是一个测试,我会选择对您的事务进行编程控制.

另请注意,@Transactionalrunnable上的注释将不起作用(除非您使用的是aspectj),因为runnables不是由spring管理的!

@RunWith(SpringJUnit4ClassRunner.class)
//other spring-test annotations; as your database context is dirty due to the committed transaction you might want to consider using @DirtiesContext
public class TransactionTemplateTest {

@Autowired
PlatformTransactionManager platformTransactionManager;

TransactionTemplate transactionTemplate;

@Before
public void setUp() throws Exception {
    transactionTemplate = new TransactionTemplate(platformTransactionManager);
}

@Test //note that there is no @Transactional configured for the method
public void test() throws InterruptedException {

    final Contract c1 = transactionTemplate.execute(new TransactionCallback<Contract>() {
        @Override
        public Contract doInTransaction(TransactionStatus status) {
            Contract c = contractDOD.getNewTransientContract(15);
            contractRepository.save(c);
            return c;
        }
    });

    ExecutorService executorService = Executors.newFixedThreadPool(5);

    for (int i = 0; i < 5; ++i) {
        executorService.execute(new Runnable() {
            @Override  //note that there is no @Transactional configured for the method
            public void run() {
                transactionTemplate.execute(new TransactionCallback<Object>() {
                    @Override
                    public Object doInTransaction(TransactionStatus status) {
                        // do whatever you want to do with c1
                        return null;
                    }
                });
            }
        });
    }

    executorService.shutdown();
    executorService.awaitTermination(10, TimeUnit.SECONDS);

    transactionTemplate.execute(new TransactionCallback<Object>() {
        @Override
        public Object doInTransaction(TransactionStatus status) {
            // validate test results in transaction
            return null;
        }
    });
}

}

Answer 3

我知道由于这种丑陋的匿名内部类使用TransactionTemplate看起来不太好，但是当出于某种原因我们想要一个测试方法事务性恕我直言时，它是最灵活的选择。

在某些情况下（取决于应用程序类型），在 Spring 测试中使用事务的最佳方式是关闭@Transactional测试方法。为什么？因为@Transactional可能会导致许多假阳性测试。您可以查看此示例文章以了解详细信息。在这种情况下TransactionTemplate，当我们需要控制时，可以完美地控制事务边界。