利用httpservletrequest文件上传

将httpservletrequest转换为MultipartHttpServletRequest，利用后者getFile方法获取MulitipartFile对象，从而进行文件的各种操作

MultipartResolver resolver = new CommonsMultipartResolver(request.getSession().getServletContext());
                MultipartHttpServletRequest req = resolver.resolveMultipart(request);
                MultipartFile file = req.getFile("myfile");
                String s =file.getOriginalFilename();
                System.out.println(s);