springmvc上传文件报错org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [org.springframework.web.multipart.MultipartFile]

在用springmvc+mybatis进行项目开发时，上传文件抛异常...

org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [org.springframework.web.multipart.MultipartFile]: Specified class is an interface
    org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:101)
    org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveModelAttribute(HandlerMethodInvoker.java:762)
    org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveHandlerArguments(HandlerMethodInvoker.java:356)
    org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:171)
    org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:426)
    org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:414)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:790)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644)
    org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:560)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:646)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
    org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:198)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)

解决方法：在Controller的MultipartFile参数前面加上@RequestParam就行了！

如：

@RequestMapping("/save")
    public String save(User user,
            HttpServletResponse response,
            @RequestParam MultipartFile file_pic//接收图片
            )throws Exception{
        
        //原始名称
        String originalFilename = file_pic.getOriginalFilename();
        //上传图片
        if(file_pic!=null && originalFilename!=null && originalFilename.length()>0){
            //存储图片的物理路径
            String pic_path = "G:\nfsysuems\temp\";
            //新的图片名称
            String newFileName = UUID.randomUUID() + originalFilename.substring(originalFilename.lastIndexOf("."));
            //新图片
            File newFile = new File(pic_path+newFileName);
            //将内存中的数据写入磁盘
            file_pic.transferTo(newFile);
            //新图片写入user
            user.setPic(newFileName);
        }
      .......