EJB 3.1 @LocalBean vs no注释

I understand the difference between local view, remote view and no-interface view. I just don't understand what is the difference between "no view" (no annotation) and no-interface view. And also why should I annotate my interface with @Local? What if I don't annotate the interface in at all, is there a difference?

我理解本地视图、远程视图和无接口视图之间的区别。我只是不明白“无视图”(无注释)和“无接口视图”之间的区别。为什么我要用@Local注释我的接口呢?如果我不注释接口呢，有什么区别吗?

4 个解决方案

#1

119

The rules are (from memory):

规则是(根据记忆):

Bean has a @LocalBean annotation -> bean has a no-interface view
Bean有一个@LocalBean注释——> Bean有一个无接口视图
Bean has a @Local annotation -> bean has a local view
Bean有一个@Local注释—> Bean有一个本地视图。
Bean has a @Remote annotation -> bean has a remote view
Bean有一个@Remote注释——> Bean有一个远程视图
Bean has no view annotations, but directly implements an interface which has a @Local annotation -> bean has a local view
Bean没有视图注释，但是直接实现了一个接口，接口有一个@Local注释——> Bean有一个本地视图
Bean has no view annotations, but directly implements an interface which has a @Remote annotation -> bean has a remote view
Bean没有视图注释，但是直接实现了一个接口，接口有一个@Remote annotation——> Bean有一个远程视图
Bean has no view annotations, but directly implements an interface which has no view annotations -> bean has a local view
Bean没有视图注释，但是直接实现了一个没有视图注释的接口——> Bean有一个本地视图
Bean has no view annotations, and implements no interfaces -> bean has a no-interface view
Bean没有视图注解，没有接口——> Bean有一个无接口视图。

So, using @LocalBean and using no annotation at all are both ways of getting a no-interface view. If you just want a no-interface view, then the simplest thing is not to annotate. Provided you're not also implementing any interfaces.

因此，使用@LocalBean和完全不使用注释都是获得无接口视图的方法。如果您只想要一个无接口视图，那么最简单的事情就是不要注释。如果您没有实现任何接口。

Part of the reason @LocalBean exists to add a no-interface view to a bean which also has an interface view. I imagine the scenario uppermost in the spec authors' minds was one where you have a bean like:

@LocalBean存在的部分原因是向同样具有接口视图的bean添加无接口视图。我想规范作者们脑海中最重要的场景是这样的:

@Stateless
public class UserPreferences {
    public String getPreference(String preferenceName);
    public Map<String, String> getPreferences();
}

Where you would want to expose both methods locally, but only the coarser-grained getPreferences() remotely. You can do that by declaring a remote interface with just that method, then just slapping @LocalBean on the bean class. Without it, you'd have to write a pointless local interface just to expose both methods locally.

您希望在本地公开这两个方法，但只远程公开粗粒度的getPreferences()。您可以使用该方法声明远程接口，然后在bean类上使用@LocalBean。如果没有它，您将不得不编写一个毫无意义的本地接口来在本地公开这两个方法。

Or, to look at it another way, the @LocalBean exists because there is such a thing as a no-interface view, and the no-annotation option exists as a handy shortcut.

或者，换个角度来看，@LocalBean之所以存在，是因为存在一个无接口视图，而无注释选项作为一个方便的快捷方式存在。

4 个解决方案

#1

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