为什么Spring Propagation=REQUIRED跨越嵌套逻辑事务

Question

似乎当具有嵌套传播的事务性spring方法调用另一个需要传播的事务性方法时，内部事务可以强制回滚外部逻辑事务。

例如，如果事务性方法Classa.MethodA（具有propagation=REQUIRED）调用事务性方法ClassB.MethodB（具有propagation=NESTED)，MethodB（具有propagation=REQUIRED）又调用事务性方法ClassC.MethodC（具有propagation=REQUIRED），那么如果ClassC.MethodC发起回滚，则由Classa.MethodA开始的外部逻辑事务将在尝试提交时得到一个UnexpectedDrollBackException。

下面是上面讨论的代码示例：

public class ClassA {
  private ClassB classB;
  @Transactional(propagation = Propagation.REQUIRED)
  public void methodA() {
    try {
      classB.methodB();
     } catch (RuntimeException re) {
       // do nothing we don't want to fail, but alas we will get an UnexpectedRollbackException
     }
  }
}

public class ClassB {
  private ClassC classC;
  @Transactional(propagation = Propagation.NESTED)
  public void methodB() {
      classC.methodC();
  }
}

public class ClassC {
  @Transactional(propagation = Propagation.REQUIRED)
  public void methodC() {
      // If this method weren't transactional this would just return to the save point created by method B
      // I Want to just fail the NESTED transaction, but alas I'm going to fail everything
      throw new RuntimeException("Oh, woe is me!");
  }
}

Answer 1

我不知道为什么会这样，但我找到了一个解决办法：

    public class ClassA {
        private ClassB classB;

        public void methodA() {
            try {
                classB.methodB();
            } catch (RuntimeException re) {
                // do nothing we don't want to fail, but alas we will get an UnexpectedRollbackException
            }
        }
    }

    public class ClassB {
        private ClassC classC;

        @Transactional(propagation = Propagation.NESTED)
        public void methodB() {
            classC.methodC();
        }
    }

    public class ClassC {
        private TransactionTemplate requiredTransaction = createRequiredTransactionTemplate();

        public void methodC() {
            if (TransactionSynchronizationManager.isActualTransactionActive()) {
                // We are already in transaction, do not wrap in transaction
                _methodC();
            } else {
                requiredTransaction.execute(cb -> {
                    _methodC();
                    return null;
                });
            }
        }

        private void _methodC() {
            throw new RuntimeException("Oh, woe is me!");
        }
    }