spring mvc --上传文件，文件和其他数据一起提交

jsp: 
      var formdata = new FormData();
      formdata.append('file', $('#file')[0].files[0]); //上传文件
      formdata.append('id', $('#id').val()); //id
      formdata.append('temp_id', temp_id);
      formdata.append('deadline', deadline);
      $.ajax({
          type: "POST",
          url: 'file/save.do',
          data: formdata,
          dataType:'json',
          processData:false,
          contentType:false,
          cache: false,
          success: function(data){
          }
      });

Controller:
   @RequestMapping(value="/save")
	@ResponseBody
	public Json save(@RequestParam(value="file", required = false) MultipartFile file,
					 @RequestParam(value="id",required = false) String id,
					 @RequestParam(value="temp_id",required = false) String temp_id,
		@RequestParam(value="deadline",required = false) String deadline) throws Exception{
		
}

jsp页面图片预览及简单的格式验证：

 <img id="imgShow" src="" height="100" width="100">
<in