异步 Servlet 异常

Question

我是JavaEE 6的新手，我了解到它支持称为AsyncServlets的异步servlet。所以我尝试使用 JavaEE6 创建一个小程序。

这是我的servlet代码

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

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        AsyncContext aCtx = request.startAsync(request, response);
        Executor executor = Executors.newSingleThreadExecutor();
        executor.execute(new MyClass(aCtx));
        System.out.println("Original thread is freed");
    }


} 

但是当我尝试运行servlet时，我得到一个异常java.lang.IllegalStateException：不支持。我正在使用tomcat 7.0.14作为服务器。我没有创建网络.xml。此代码中的问题在哪里？

编辑：

这是异常的完整堆栈跟踪

SEVERE: Servlet.service() for servlet [AsyncServlet] in context with path [/AsyncTest] threw exception
java.lang.IllegalStateException: Not supported.
at org.apache.catalina.connector.Request.startAsync(Request.java:1618)
at org.apache.catalina.connector.RequestFacade.startAsync(RequestFacade.java:1031)
at javax.servlet.ServletRequestWrapper.startAsync(ServletRequestWrapper.java:379)
at com.icbt.demo.servlet.AsyncServlet.doGet(AsyncServlet.java:30)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:462)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:563)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:399)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:317)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:204)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:311)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662) 

Answer 1

如果你使用tomcat作为你的Web服务器，那么你应该维护你将使用asyc请求来tomcat

。

在开始异步请求之前放置此行代码

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

我希望你能从中得到你想要的

Answer 2

如果应用程序尝试启动异步操作，并且请求处理链中存在不支持异步处理的 servlet 或 servlet 过滤器，则会抛出 IllegalStateException。所以可能会有一些错误.plz检查你的代码。