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="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);
    }