spring-mvc 前端post表单数据到后台，后台没有接收到，并且用HttpServletRequest获取参数列表为空，下面为代码：

web.xml:

<servlet>         <servlet-name>embers</servlet-name>         <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>         <init-param>             <param-name>contextConfigLocation</param-name>             <param-value>classpath:conf/embers-mvc.xml</param-value>         </init-param>         <load-on-startup>1</load-on-startup>         <async-supported>true</async-supported>     </servlet>      <servlet-mapping>         <servlet-name>embers</servlet-name>         <url-pattern>/rest/*</url-pattern>     </servlet-mapping> 

mvc配置文件：

<context:component-scan base-package="embers.blog.controller" />

controller：

@Controller public class BugTestController {               @RequestMapping(value="/demo",method=RequestMethod.POST)     public String demo(HttpServletRequest request,HttpServletResponse response) throws IOException{         System.out.println(request.getParameterMap());         System.out.println(request.getParameter("username"));         System.out.println(request.getParameter("password"));         System.out.println(request.getContentType());         System.out.println("//");         response.setContentType("text/html");         response.getWriter().println("keke");         response.getWriter().flush();         response.getWriter().close();         return null;     } }

我已经调试过无数次了，如果设定为GET方法，然后把参数放在URL上是完全没有问题的，用json提交，配置json转换也是没有问题的，就是默认的POST表单数据有问题，下面是调试工具生成的表单完整报文：

POST /BugTest/rest/demo HTTP/1.1 Host: 127.0.0.1:8080 Content-Type: application/x-www-form-urlencoded Cache-Control: no-cache  username=111wqfewrf&password=321&=

一直都是好好的，这么简单的demo，现在突然不行了，好久没写springmvc了，我漏了什么吗？