Servlets java.lang.IllegalStateException:调用[asyncDispatch（）]对于异步状态为[COMPLETING]的请求无效

我有以下异步Servlet、相应的侦听器和异步处理器类

AsyncProcessor.java：

public class AsyncProcessor implements Runnable {

    private AsyncContext asyncContext;

    public AsyncProcessor(AsyncContext asyncContext, String view) {
        this.asyncContext = asyncContext;
        this.asyncContext.getRequest().setAttribute("dispatch", view);
    }

    public void run() {
        try {
            Thread.sleep(10*1000);
            asyncContext.complete();
        } catch(Exception e) {
        }
    }

}

MyServlet13.java：

@WebServlet(name="myServlet13", urlPatterns="/servlet13", asyncSupported=true)
public class MyServlet13 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        AsyncContext asyncContext = request.startAsync();
        System.out.println("Before starting Async processing");
        asyncContext.addListener(new MyAsyncListener());
        Executor executor = (Executor)getServletContext().getAttribute("executor");
        asyncContext.start(new AsyncProcessor(asyncContext, "/jsp13.jsp"));
        System.out.println("After starting Async processing");
    }

}

MyAsyncListener.java：

public class MyAsyncListener implements AsyncListener {

    public void onStartAsync(AsyncEvent asyncEvent) throws IOException {
        System.out.println("This is from onStartAsync");
    }

    public void onComplete(AsyncEvent asyncEvent) throws IOException {
        System.out.println("This is from onComplete, before dispatch");
        AsyncContext asyncContext = asyncEvent.getAsyncContext();
        asyncContext.dispatch("/jsp13.jsp");
        asyncContext.getResponse().getWriter().println("Async tasks completed...<br>");
        System.out.println("This is from onComplete, after dispatch");
    }

    public void onTimeout(AsyncEvent asyncEvent) throws IOException {
        System.out.println("This is from onTimeout");
    }

    public void onError(AsyncEvent asyncEvent) throws IOException {
        System.out.println("This is from onError");
    }

}

公共类MyAsyncListener实现AsyncListener{
公共void onStartAsync（AsyncEvent AsyncEvent）引发IOException{
System.out.println（“这是来自onStartAsync”）；
}
public void onComplete（AsyncEvent AsyncEvent）引发IOException{
System.out.println（“这是从onComplete发送的，在发送之前”）；
AsyncContext=asyncEvent.getAsyncContext（）；
asyncContext.dispatch（“/jsp13.jsp”）；
asyncContext.getResponse（）.getWriter（）.println（“异步任务已完成…
”；
System.out.println（“这是从onComplete发送的，发送后”）；
}
public void onTimeout（AsyncEvent AsyncEvent）引发IOException{
System.out.println（“这是来自onTimeout”）；
}
public void onError（AsyncEvent AsyncEvent）引发IOException{
System.out.println（“这是来自onError”）；
}
}

当我尝试用/servlet13 url模式调用

MyServlet13

时，我得到以下异常

java.lang.IllegalStateException:调用[asyncDispatch（）]对于异步状态为[COMPLETING]的请求无效

不确定这个代码有什么问题

根据servlet3.0规范，我们可以将AsyncListener添加到获得的

AsyncContext

它将能够听到各种事件。在我的例子中，应该监听

onComplete（）

，并将请求发送到

jsp13.jsp

视图（我的web应用程序上下文中确实有

jsp13.jsp

）

---

我使用的是最新版本的tomcat 7.0.x和servlet 3.0规范，这是行不通的。您已完成请求，无法再次发送。complete（）结束您的周期，响应已经发送。

有趣的是，有时我会看到上面的错误，有时会看到一个空白页
FYI，调用AsyncListener的onComplete（），我可以在服务器控制台上看到“这是从onComplete发送的，发送后”