Spring MVC 项目在使用 DeferredResult 实现异步接口时出现错误。

完整错误信息如下：

十一月 03, 2017 8:59:53 上午 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet [SpringMVC] in context with path [/smarthome] threw exception [Request processing failed; nested exception is java.lang.IllegalStateException: Async support must be enabled on a servlet and for all filters involved in async request processing. This is done in Java code using the Servlet API or by adding "<async-supported>true</async-supported>" to servlet and filter declarations in web.xml.] with root cause
java.lang.IllegalStateException: Async support must be enabled on a servlet and for all filters involved in async request processing. This is done in Java code using the Servlet API or by adding "<async-supported>true</async-supported>" to servlet and filter declarations in web.xml.at org.springframework.util.Assert.state(Assert.java:385)at org.springframework.web.context.request.async.StandardServletAsyncWebRequest.startAsync(StandardServletAsyncWebRequest.java:104)at org.springframework.web.context.request.async.WebAsyncManager.startAsyncProcessing(WebAsyncManager.java:431)at org.springframework.web.context.request.async.WebAsyncManager.startDeferredResultProcessing(WebAsyncManager.java:409)at org.springframework.web.servlet.mvc.method.annotation.DeferredResultMethodReturnValueHandler.handleReturnValue(DeferredResultMethodReturnValueHandler.java:51)at org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:71)at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:122)at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:749)at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:690)at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83)at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:945)at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:876)at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:852)at javax.servlet.http.HttpServlet.service(HttpServlet.java:622)at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)at com.wanyu.frame.base.AuthFilter.doFilter(AuthFilter.java:97)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:108)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:94)at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:504)at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:509)at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1104)at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:684)at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1524)at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1480)at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)at java.lang.Thread.run(Thread.java:745)

在错误信息中，唯一涉及到自己写的代码的信息只有一行：

com.wanyu.frame.base.AuthFilter.doFilter(AuthFilter.java:97)

相关代码如下：

  @Overridepublic void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)throws IOException, ServletException {HttpServletRequest req = (HttpServletRequest) request;HttpServletResponse res = (HttpServletResponse) response;String requestURI = req.getRequestURI().substring(req.getRequestURI().indexOf("/", 1),req.getRequestURI().length());System.out.println("requestURI=" + requestURI);// 如果没有登录if (p == null) { // &&// !requestURI.equals("/controller/personal/login.do")，不使用此验证，把不需要登录的都映射为:/publicResponseUtils.outFailureJson(res, BaseCodeMessage.personal_10000);} else {req.setAttribute(ConstantDict.SESSION_USER, p);// 继续访问其他资源chain.doFilter(req, res); //这里为发生错误的语句}}

解决方法

这个问题怎么解决呢？

其实错误提示中已经写的很清楚了：

java.lang.IllegalStateException: Async support must be enabled on a servlet and for all filters involved in async request processing. This is done in Java code using the Servlet API or by adding "<async-supported>true</async-supported>" to servlet and filter declarations in web.xml.

需要在 web.xml 文件中的 filter 和 servlet 定义中添加："<async-supported>true</async-supported>"

以下是完整的 web.xml，请参考"<async-supported>true</async-supported>"出现的位置：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns="http://java.sun.com/xml/ns/javaee"xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"version="3.0"><display-name>Archetype Created Web Application</display-name><context-param><param-name>contextConfigLocation</param-name><param-value>classpath:spring-mybatis.xml</param-value></context-param><context-param><param-name>spring.profiles.active</param-name><param-value>dev</param-value></context-param><context-param><param-name>spring.profiles.default</param-name><param-value>dev</param-value></context-param><context-param><param-name>spring.liveBeansView.mbeanDomain</param-name><param-value>dev</param-value></context-param><filter><filter-name>encodingFilter</filter-name><filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class><async-supported>true</async-supported><init-param><param-name>encoding</param-name><param-value>UTF-8</param-value></init-param><init-param><param-name>forceEncoding</param-name><param-value>true</param-value></init-param></filter><filter-mapping><filter-name>encodingFilter</filter-name><url-pattern>/*</url-pattern></filter-mapping><!-- 不管是在前面还是在最后，都无法使用@Autowired和@Resource --><filter><filter-name>AuthFilter</filter-name><filter-class>com.wanyu.frame.base.AuthFilter</filter-class><async-supported>true</async-supported></filter><filter-mapping><filter-name>AuthFilter</filter-name><url-pattern>/page/*</url-pattern></filter-mapping><filter-mapping><filter-name>AuthFilter</filter-name><url-pattern>/webapi/*</url-pattern></filter-mapping><filter-mapping><filter-name>AuthFilter</filter-name><url-pattern>/mobileapi/*</url-pattern></filter-mapping><listener><listener-class>org.springframework.web.context.ContextLoaderListener</listener-class></listener><listener><listener-class>org.springframework.web.util.IntrospectorCleanupListener</listener-class></listener><listener><listener-class>org.springframework.web.util.Log4jConfigListener</listener-class></listener><servlet><servlet-name>SpringMVC</servlet-name><servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class><init-param><param-name>contextConfigLocation</param-name><param-value>classpath:spring-mvc.xml</param-value></init-param><load-on-startup>1</load-on-startup><async-supported>true</async-supported></servlet><servlet-mapping><servlet-name>SpringMVC</servlet-name><url-pattern>/</url-pattern></servlet-mapping><welcome-file-list><welcome-file>/index.jsp</welcome-file></welcome-file-list><error-page><error-code>404</error-code><location>/static/error/404.html</location></error-page><error-page><error-code>500</error-code><location>/static/error/500.html</location></error-page>
</web-app>