IllegalStateException异常：不支持AsyncContext.startAsync（REQ，RES） [英] IllegalStateException: Not supported on AsyncContext.startAsync(req, res)

问题描述

我已经创建了一个servlet 3.0探索异步请求处理：

I have created a servlet 3.0 to explore asynchronous request processing:

@WebServlet(name="MyTest", urlPatterns={"/MyTest"}, asyncSupported=true)
public class MyTest extends HttpServlet {

    @Override
    public void doGet(HttpServletRequest req, HttpServletResponse res)
            throws ServletException, IOException {

        AsyncContext tmp = req.startAsync(req, res);
        ...

    }    

}

但我得到一个 IllegalStateException异常在 .startAsync（...）被调用。我知道的Javadoc提到的例外，但我没有明确地启用异步（参考 WebServlet 注释）。我使用Tomcat 7.0.11.0与NetBeans交付。

but I get an IllegalStateException when .startAsync(...) is called. I know the Javadoc mentions that exception, but I did explicitly enable async (c.f. WebServlet annotation). I am using Tomcat 7.0.11.0 delivered with NetBeans.

我可以证实， req.isAsyncSupported（）终止返回false。我究竟做错了什么？更重要的是，我需要做的，使异步处理？

I could confirm that req.isAsyncSupported() is returning false. What am I doing wrong? What more do I need to do to enable async processing?

编辑：

我试图实施以下例如并得到了相同的问题。

I tried to implement the following example and got the same issue.

推荐答案

我检查了Tomcat的code，只见那asyncSupported变量必须显式地设置为true。这就是为什么你得到 req.isAsyncSupported（）==假。

I checked out Tomcat's code and saw that the asyncSupported variable has to be explicitly set to true. That's why you are getting req.isAsyncSupported() == false.

您可以尝试通过以下方法之一设置在HttpServletRequest对象为true异步属性。

You could try to set the async attribute in the HttpServletRequest object to true by one of the following methods.

req.setAttribute("org.apache.catalina.ASYNC_SUPPORTED", true);

或

((org.apache.catalina.connector.Request)req).setAsyncSupported(true);

希望它帮助。

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