springmvc上传文件异常

症状：

error:
org.springframework.web.multipart.MultipartException: Current request is not a multipart request
at org.springframework.web.method.annotation.RequestParamMethodArgumentResolver.handleMissingValue(RequestParamMethodArgumentResolver.java:188)
at org.springframework.web.method.annotation.AbstractNamedValueMethodArgumentResolver.resolveArgument(AbstractNamedValueMethodArgumentResolver.java:104)
at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:121)
at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:161)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:128)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:114)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)

原因：

jsp中form表单 ajax提交 不能用序列化，序列化方法只能序列化非文件格式的数据 文件格式则不被序列化，后台接收不到文件数据

用 FormData来封装数据

解决方法：

jquery尽量用新版

js:

     var formData = new FormData($( "#addMemberForm" )[0]);  

         $.ajax({
             type : "POST",
             url : "<%=basePath%>manage/memberActive/add",
             data : formData,
             async: false,
             cache: false,
             dataType : "json",
             contentType: false,
              processData: false,
             success: function(result){
                      console.log(result);
                      if(result){
                              window.location.href = "<%=basePath%>manage/memberActive/list";

                      }else{
                         alert(result.msg);
                      }
                    }
         });

jsp:

 <form id="addMemberForm" >
 <div class="loadingActive-left">
 <input type="text" name="titel" id="titel" placeholder="请输入标题" ></input>
 <div class="uploadBox">
 <div class="big-photo">
 <div id="preview">
 <img id="imghead" border="0" src="<%=basePath%>resources/images/upload.jpg" width="270"
 height="100" onclick="$('#previewImg').click();"></img>
 </div>
 <input type="file" onchange="previewImage(this)"
 style="display: none;" id="previewImg" name="file"></input>
 </div>
 </div>
 <textarea style="width:100%; height:41%;resize:none" rows="9" cols="75" name="content" id="content" placeholder="请输入内容..." ></textarea>
 </div>
 </form>

action:

 　　 @RequestMapping(value = "add", method = RequestMethod.POST)
     @ResponseBody
     public BaseResponse<Boolean> addMemberActivity(HttpServletRequest request,
             @RequestParam(value = "file", required = false) MultipartFile file) throws IOException {
         MemberActivity mActivitie = new MemberActivity();
         UploadUtils up = new UploadUtils();
         String Imgname = file.getOriginalFilename().substring(0, file.getOriginalFilename().length() - 4);
         String url = up.uploadFile(1, 1, Imgname, file);
         mActivitie.setStatusId((short) 1);
         mActivitie.setTitel(request.getParameter("titel"));
         mActivitie.setCoverUrl(url);
         mActivitie.setShortDesc("无简介");
         mActivitie.setContent(request.getParameter("content"));
         mActivitie.setTotalPrice(0.01);
         mActivitie.setDiscountPrice(0.01);
         mActivitie.setCreateTime(new Timestamp(System.currentTimeMillis()));
         memberActivityService.addMemberActivity(mActivitie);
         return new BaseResponse<Boolean>(true);
     }