Question

我有以下课程：

@Transactional
public class MyClass{
    @Transactional(propagation=Propagation.REQUIRES_NEW)
    public void method1(){
         ....
         myDao.update(entity);
    }

    public void method2(){
         method1();             
         //I need to be sure that data was persisted to DB and find the entity by id    

         MyEntity ent=myDao.find(entityId);
         //entity is not updated here
    }

}

但实际上我无法在方法2中从DB中读取更新的实体。怎么做到这一点？我需要在method2中在method1（）调用之后更新值，因此应该提交method1中的事务并且结果是可见的。怎么做？

Answer 1

您必须在另一个类中执行此操作，因为在调用本地方法时不遵循@Transactional（这取决于Spring代理的工作方式，本地方法调用通过调用{来绕过事务代理{1}}）。

解决方案可能看起来像这样：

this

Answer 2

我重新创建了你的场景（嵌入式数据库）：首先，我向数据库添加任何内容，如：

 public void initialize() {
    Sample startEntity = new Sample();
    startEntity.setId(1);
    startEntity.setName("Start name");
    sampleRepository.saveSample(startEntity);
    sampleRepository.flush(); // <-- just to make sure scenario is recreated
    sampleRepository.clear(); // same as above
    LOGGER.info(sampleRepository.findSampleById(1));
    sampleRepository.clear(); // same as above above :D
}

之后，我们在数据库中获得了一个实体Sample（所有事务都结束了，缓存被清除）;

控制台：

Hibernate: insert into sample (name, id) values (?, ?)
Hibernate: select sample0_.id as id1_0_0_, sample0_.name as name2_0_0_ from sample sample0_ where sample0_.id=?
2016-04-20 15:58:21.762  INFO 5764 --- [           main] com.patrykwoj.service.BasicServiceTest   : Sample [id=1, name=Start name]

现在你的例子：

@Transactional
@Component
public class SampleService {

private static final Logger LOGGER = Logger.getLogger(SampleService.class);

@Autowired
SampleRepository sampleRepository;

@Transactional (propagation = Propagation.REQUIRES_NEW)
public void method1() {
    Sample someSample = new Sample();
    someSample.setId(1);
    someSample.setName("TestSample before update but after create");
    sampleRepository.updateSample(someSample);
}

public void method2() {
    method1();
    // I need to be sure that data was persisted to DB and find the entity by id

    Sample someSampleAfterUpdate = sampleRepository.findSampleById(1); //I believe that at that point sample is found in L-1 cache not in db directry.
    // entity is not updated here
    LOGGER.info(someSampleAfterUpdate); //in this point, transaction is not over yet, so you wont notice change in database..
}
}

然后从您的代码执行控制台：

Hibernate: select sample0_.id as id1_0_0_, sample0_.name as name2_0_0_ from sample sample0_ where sample0_.id=?
2016-04-20 16:02:17.903  INFO 5044 --- [           main] com.patrykwoj.service.SampleService      : Sample [id=1, name=TestSample before update but after create]
Hibernate: update sample set name=? where id=?
2016-04-20 16:02:17.903  INFO 5044 --- [           main] com.patrykwoj.StackOverfloApplication    : Method2 is over

主要课程：

@Override
public void run(String... strings) throws Exception {
  basicServiceTest.initialize();
  sampleService.method2();
  LOGGER.info("Method2 is over");
}

在我看来，一切看起来都不错。它按预期工作。我在您的代码中发表了一些评论，但无论如何都应该清楚控制台输出。

java spring 4 @Transactional嵌套事务问题

2 个答案: