在使用springmvc上传图片时碰到的 The current request is not a multipart request问题

使用springmvc的commons-fileupload上传文件或者图片时遇到的问题以及解决方案。。。

后台报的错误是这样的：

org.springframework.web.multipart.MultipartException: The current request is not a multipart request
    at org.springframework.web.method.annotation.RequestParamMethodArgumentResolver.assertIsMultipartRequest(RequestParamMethodArgumentResolver.java:185)
    at org.springframework.web.method.annotation.RequestParamMethodArgumentResolver.resolveName(RequestParamMethodArgumentResolver.java:150)
    at org.springframework.web.method.annotation.AbstractNamedValueMethodArgumentResolver.resolveArgument(AbstractNamedValueMethodArgumentResolver.java:86)
    at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:77)省略...

我的Controller是这样的，

@ResponseBody
@RequestMapping("/updateuser")
	public Object update(@RequestParam(value="userId") int userId,@RequestParam(value="headPhoto",required=false)MultipartFile headPhoto）throws Exception{     

		User user = new User();
		user.setUserId(userId);

		if(headPhoto!=bull)String pic_path = "F:\\upload\\img\\head\\";
			String pic_zip_path = "F:\\upload\\img\\head\\zip\\";
			String orignName = file.getOriginalFilename();
			System.out.println(orignName);
			String newName = UUID.randomUUID() + orignName.substring(orignName.indexOf("."));
			File newFile = new File(pic_path+newName);
			File zipFile = new File(pic_zip_path+newName);
			headfile.transferTo(newFile);			
			ImageZipUtil.zipImageFile(newFile, zipFile, 256, 0, 1);
			user.setHeadPhoto(newName);}

}

那么问题来了，，你以为加一个required=false就不传file可以了吗？不是的。。。 

Spring在处理请求映射的时候，如果发现某个请求参数是MultipartFile类型的，会判断请求是否是MultipartHttpServletRequest，如果请求不是这个类型，即使参数不是必须的(required=false)，也会抛出异常。

改后：

@ResponseBody
	@RequestMapping("/updateuser")
	public Object update(
			HttpServletRequest request)throws Exception{
		User user = new User();
		user.setUserId(Integer.parseInt(request.getParameter("userId")));
		user.setTrueName(request.getParameter("realName"));
		user.setNeakName(request.getParameter("neckName"));
		user.setSex(request.getParameter("sex"));
		if (request instanceof MultipartHttpServletRequest) {
			MultipartFile file =  ((MultipartHttpServletRequest) request).getFile("headPhoto");
			if(file!=null){
			String pic_path = "F:\\upload\\img\\head\\";
			String pic_zip_path = "F:\\upload\\img\\head\\zip\\";
			String orignName = file.getOriginalFilename();
			System.out.println(orignName);
			String newName = UUID.randomUUID() + orignName.substring(orignName.indexOf("."));
			File newFile = new File(pic_path+newName);
			File zipFile = new File(pic_zip_path+newName);
			file.transferTo(newFile);
			ImageZipUtil.zipImageFile(newFile, zipFile, 256, 0, 1);
			user.setHeadPhoto(newName);
		}
	    }
		return userService.updateUse(user);
	}

OK了，解决。