CDI范围在非http应用程序中

Question

我正在开发一个没有http接口的Java EE应用程序:它只使用MQTT来发送/接收数据.

我想知道是否CDI @SessionScoped和@RequestScoped适用于这种情况,或者有定义自定义范围来处理客户端的请求.

编辑

我尝试了一个简单的应用程序,在mqtt接收回调中注入一个@SessionScoped或@RequestScopedbean,我得到一个异常,说我没有活动的上下文.

是否可以以编程方式激活上下文,以便bean的生命周期遵循所选范围？

PS:当我发布问题时,我并不是太懒于进行那么简单的测试,但我很想在CDI范围理论中更深入......而且我仍然是......

Answer 1

您可能需要创建自己的请求或会话上下文.

这当然是CDI实施和特定应用.

例如,如果您使用Weld并需要Request Scope,则可以创建并激活org.jboss.weld.context.bound.BoundRequestContext.

      /* Inject the BoundRequestContext. */

   /* Alternatively, you could look this up from the BeanManager */

   @Inject BoundRequestContext requestContext;


   ...


   /* Start the request, providing a data store which will last the lifetime of the request */

   public void startRequest(Map<String, Object> requestDataStore) {

      // Associate the store with the context and activate the context

      requestContext.associate(requestDataStore);

      requestContext.activate();

   }


   /* End the request, providing the same data store as was used to start the request */

   public void endRequest(Map<String, Object> requestDataStore) {

      try {

         /* Invalidate the request (all bean instances will be scheduled for destruction) */

         requestContext.invalidate();

         /* Deactivate the request, causing all bean instances to be destroyed (as the context is invalid) */

         requestContext.deactivate();

      } finally {

         /* Ensure that whatever happens we dissociate to prevent any memory leaks */

         requestContext.dissociate(requestDataStore);

      }

   }

你可以在这里找到信息和这个例子https://docs.jboss.org/weld/reference/latest/en-US/html/contexts.html

也适用于BoundConversationContext.会话范围稍微困难一点,您需要在应用程序中提供真正的会话支持才能实现它.