是否可以将@RequestScoped bean @Inject 到@Stateless EJB 中? [英] Is it possible to @Inject a @RequestScoped bean into a @Stateless EJB?

问题描述

是否可以将请求范围的 CDI bean 注入无状态会话 bean 中?

Is it possible to inject a request-scoped CDI bean into a Stateless session bean?

我问了一个相关的问题，并认为具体的 CDI @RequestScoped 到 @Stateless 问题值得自己发表.

I had asked a related question and thought the specific CDI @RequestScoped into @Stateless question merited its own post.

在 EJB 方法/@RequestScoped 和 @Stateless 之间传递状态

我也问了一个关于 JMS @MessageDriven beans 的类似问题 - 基本上想知道关于 @Stateless 的相同问题.

I also asked a similar question about JMS @MessageDriven beans - basically want to know the same about @Stateless.

@RequestScoped CDI 注入@MessageDriven bean

推荐答案

你绝对可以做你提到的事情并在 @Stateless 会话 bean 中使用 @RequestScoped bean 和@MessageDriven bean.这是 CDI 规范和 TCK 的核心部分，保证可移植.

You can absolutely do what you mention and use @RequestScoped beans in an @Stateless session bean and an @MessageDriven bean. This is a core part of the CDI spec and TCK and guaranteed portable.

请注意，有一个使用 @RequestScoped bean 的 @Stateless bean 的测试，但没有保证 @MessageDriven 的测试 bean 可以引用 @RequestScoped bean.这只是一个疏忽，已经针对 Java EE 7 TCK 修复.所以请注意，如果它不适用于 MDB 案例，那可能不是你的错:)

Do be aware that there is a test for a @Stateless bean that uses a @RequestScoped bean, but there is no test that guarantees a @MessageDriven bean can reference @RequestScoped beans. This was just an oversight and is already fixed for the Java EE 7 TCK. So just be aware that if it doesn't work for the MDB case, it may not be your fault :)

解决方法是简单地将 MDB 委托给任何类型的 SessionBean，如 @Stateless、@Stateful 和 @Singleton都有 @RequestScoped 测试.

The workaround would be to simply have your MDB delegate to a SessionBean of any kind as @Stateless, @Stateful, and @Singleton all have @RequestScoped tests.

虽然 @Stateless、@Singleton 和 @MessageDriven 可以通过 @Inject 注入范围引用，但它们不能成为 @RequestScoped 或任何其他范围.只有 @Stateful 模型足够灵活以支持作用域.换句话说，您可以将 @Stateful bean 类本身注释为 @RequestScoped、@SessionScoped 等.

While @Stateless, @Singleton and @MessageDriven can have scoped references injected via @Inject, they cannot be @RequestScoped or any other scope. Only the @Stateful model is flexible enough to support scopes. In other words, you can annotate the @Stateful bean class itself as @RequestScoped, @SessionScoped, etc..

简单来说@Stateless，@Singleton 有固定的作用域"；已经.@Singleton 本质上是 @ApplicationScoped 并且 @Stateless 可能是一些像 @InvocationScoped 这样的虚构作用域，如果那个存在.@MessageDriven bean 的生命周期完全取决于驱动它的连接器，因此也不允许具有用户定义的范围.

In simple terms @Stateless, @Singleton have fixed "scopes" already. @Singleton is essentially @ApplicationScoped and @Stateless would perhaps be some made-up scope like @InvocationScoped, if that existed. The lifecycle of an @MessageDriven bean is entirely up to the Connector that drives it and is therefore also not allowed to have user-defined scope.

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