JSF2.0 Tomcat7中的@Named和@ManagedBean注释之间的区别 [英] Difference between @Named and @ManagedBean annotations in JSF2.0 Tomcat7

问题描述

这可能是一个noob问题，但是在很多教程和示例中，我看到这些注释的使用就好像他们做了同样的事情。

然而，我遇到了一些限制使用 @Named 一（特别是依赖注入等）我找不到一个来源的差异被解释，我会非常感谢，如果有人可以粗略概述何时使用一个或另一个。

解决方案

@Named 给予CDI托管bean一个EL名称用于查看技术，如JSF或JSP。请注意，在CDI应用程序中，您不要需要 @Named 注释来创建由CDI管理的bean（感谢@Karl的评论）

@ManagedBean 使由JSF管理的bean可以：

• 将其注入其他@ManagedBean注释的bean（但不是@Named beans！）


• 通过表达式语言从您的视图中访问它

看到这个相关的问题，以获取有关注射在两种类型的bean之间如何工作的更多信息。

请注意，与bean的范围不同。它们来自不同的包，但命名相同（JSF： javax.faces.bean ，CDI： javax.enterprise.context ，所以如果你包含错误的类，它通常是一个错误和混乱的根源。

从我的经验来看：尽可能使用CDI bean，因为它们更灵活比JSF管理的bean只有缺点是CDI不知道一个视图范围，所以你需要回到@ManagedBean或使用像Seam这样的第三方扩展。

This might be a noob question, however in a lot of tutorials and examples I saw these annotations used as if they did the same thing.

However I ran into some limitations using the @Named one (especially with dependency injection etc.) I couldn't find a source where the difference is explained and I'd be very thankful if someone can give a rough overview on when to use one or the other.

解决方案

@Named gives a CDI managed bean an EL name to be used in view technologies like JSF or JSP. Note that in a CDI application you don't need the @Named annotation to make a bean managed by CDI (thanks to @Karl for his comment).

@ManagedBean makes the bean managed by JSF and you can:

• inject it into other @ManagedBean annotated beans (but not into @Named beans!)
• access it from your views via expression language

See this related question for further information how injection works among both kind of beans.

Note that there is also a difference with the scope of the beans. They come from different packages but are named identically (JSF: javax.faces.bean, CDI: javax.enterprise.context , so it is often a source of error and confusion if you include the wrong class.

From my experience: You should use CDI beans whenever possible since they are more flexible than JSF managed beans. Only drawback is that CDI doesn't know a view scope, so you either need to fall back to @ManagedBean or use some third party extension like Seam.

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