java - Spring Async DeferredResult 在 Tomcat 8 中不起作用

Question

我使用 Spring 4.0.5 和 Servlet API 3.1.0 创建了一个异步 MVC 应用程序。异步行为在使用 Firefox 24 的 Jetty 8.0 中运行良好，但我无法使其在 Tomcat 8.0 和 Firefox 24 中运行。我正在使用 DeferredResult 来管理异步请求。知道我错过了什么吗？它必须是某些 Tomcat 设置或 web.xml 中的某些内容，因为完全相同的 Java 代码在 Jetty 中运行良好。

当异步请求最终有结果并且应该写入响应时，我看到记录了以下消息:

WebAsyncManager - Dispatching request to resume processing
RequestResponseBodyMethodProcessor - Written [true] as "application/json" using MappingJacksonHttpMessageConvertor
DispatcherServlet - Null ModelAndView returned to DispatcherServlet with name 'app': assuming HandlerAdapter completed request handling
DispatcherServlet - Successfully completed request

长时间运行的请求永远不会返回到我的浏览器，最终我在 Tomcat 日志中看到这个超时错误:

CoyoteAdapter.asyncDispatch Exception while processing an asynchronous request
java.lang.IllegalStateException: Calling [asyncTimeout()] is not valid for a request with Async state [Dispatching]

--服务器.xml--

    <Connector port="8080" protocol="org.apache.coyote.http11.Http11NioProtocol" 
        maxConnections="100"
               maxThreads="100"
               connectionTimeout="150000" 
               asyncTimeout="150000" />

--Tomcat web.xml--

<?xml version="1.0" encoding="ISO-8859-1"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
                      http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
  version="3.1">

    <servlet>
        <servlet-name>default</servlet-name>
        <servlet-class>org.apache.catalina.servlets.DefaultServlet</servlet-class>
        <init-param>
            <param-name>debug</param-name>
            <param-value>0</param-value>
        </init-param>
        <init-param>
            <param-name>listings</param-name>
            <param-value>false</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
        <async-supported>true</async-supported>
    </servlet>

    <servlet>
        <servlet-name>jsp</servlet-name>
        <servlet-class>org.apache.jasper.servlet.JspServlet</servlet-class>
        <init-param>
            <param-name>fork</param-name>
            <param-value>false</param-value>
        </init-param>
        <init-param>
            <param-name>xpoweredBy</param-name>
            <param-value>false</param-value>
        </init-param>
        <load-on-startup>3</load-on-startup>
        <async-supported>true</async-supported>
    </servlet>  


    <!-- The mapping for the default servlet -->
    <servlet-mapping>
        <servlet-name>default</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

    <!-- The mappings for the JSP servlet -->
    <servlet-mapping>
        <servlet-name>jsp</servlet-name>
        <url-pattern>*.jsp</url-pattern>
        <url-pattern>*.jspx</url-pattern>
    </servlet-mapping>    
</web-app>

--Spring web-app web.xml--

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
                      http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
  version="3.1">    

    <!-- Creates the Spring Container shared by all Servlets and Filters -->
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    <context-param>
        <param-name>webAppRootKey</param-name>
        <param-value>my-async-app</param-value>
    </context-param>

    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:spring/app-config.xml</param-value>
    </context-param>

    <!-- Handles all requests into the application -->
    <servlet>
        <servlet-name>app</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:spring/controllers-config.xml</param-value> 
        </init-param>
        <load-on-startup>1</load-on-startup>
        <async-supported>true</async-supported>
    </servlet>

    <!-- Maps all /app requests to the DispatcherServlet for handling -->
    <servlet-mapping>
        <servlet-name>app</servlet-name>
        <url-pattern>/app/*</url-pattern>
    </servlet-mapping>
</web-app>

Answer 1

此问题与 Tomcat 中描述的错误有关 here , here和 here .

可能的解决方案:

1. 使用更稳定的 Tomcat 版本，例如已修复此错误的 Tomcat 7.0.47。
2. 使用更高级的调度程序，例如 org.springframework.web.servlet.DispatcherServlet

3. 按照建议覆盖 HttpServlet here :

   public class AsyncServlet extends HttpServlet {
   
       protected void doGet(final HttpServletRequest request, HttpServletResponse response)
               throws ServletException, IOException {
   
           if (request.isAsyncStarted()) {
               response.getWriter().write("asyncResult=" + request.getAttribute("asyncResult"));
           } else {
               final AsyncContext asyncContext = request.startAsync(request, response);
   
               asyncContext.addListener(new AsyncListener() {
                   public void onTimeout(AsyncEvent event) throws IOException {
                       request.setAttribute("asyncResult", "timeout\n");
                       asyncContext.dispatch();
                   }
   
                   public void onStartAsync(AsyncEvent event) throws IOException {
                   }
   
                   public void onError(AsyncEvent event) throws IOException {
                   }
   
                   public void onComplete(AsyncEvent event) throws IOException {
                   }
               });
   
               asyncContext.setTimeout(5000L);
           }
       }
   }