在哪里应该放置@Transactional注释：在接口定义或实现类？ [英] Where should I put @Transactional annotation: at an interface definition or at an implementing class?

问题描述

标题中的问题：

@Transactional (readonly = true)
public interface FooService {
   void doSmth ();
}


public class FooServiceImpl implements FooService {
   ...
}

vs

public interface FooService {
   void doSmth ();
}

@Transactional (readonly = true)
public class FooServiceImpl implements FooService {
   ...
}

推荐答案

从 http://static.springsource.org/spring/docs/2.0.x/reference/transaction.html

Spring团队的建议是，您只需使用 @Transactional 注释注释具体类， 您当然可以在接口（或接口方法）上放置 @Transactional 注释，但这只会按您期望的方式工作它到如果你使用基于接口的代理。注释不是继承的事实意味着如果您使用基于类的代理，那么基于类的代理基础结构将不会识别事务设置，并且对象不会被包装在事务代理中（这将是决定性的坏）。所以，请采取Spring团队的建议，并且只用 @Transactional 注释来注释具体类（以及具体类的方法）。

The Spring team's recommendation is that you only annotate concrete classes with the @Transactional annotation, as opposed to annotating interfaces. You certainly can place the @Transactional annotation on an interface (or an interface method), but this will only work as you would expect it to if you are using interface-based proxies. The fact that annotations are not inherited means that if you are using class-based proxies then the transaction settings will not be recognised by the class-based proxying infrastructure and the object will not be wrapped in a transactional proxy (which would be decidedly bad). So please do take the Spring team's advice and only annotate concrete classes (and the methods of concrete classes) with the @Transactional annotation.

注意：由于这个机制是基于代理，只有通过代理进入的外部方法调用将被拦截。这意味着自我调用目标对象调用目标对象的一些其他方法，即使调用的方法标记有 @Transactional ！

Note: Since this mechanism is based on proxies, only 'external' method calls coming in through the proxy will be intercepted. This means that 'self-invocation', i.e. a method within the target object calling some other method of the target object, won't lead to an actual transaction at runtime even if the invoked method is marked with @Transactional!

（强调添加到第一句，其他强调从原始。）

(Emphasis added to the first sentence, other emphasis from the original.)

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