SprngMVC的文件上传

//前端传递的数据名称和实体类的属性名称相同时，可以自动注入到对象中
    //如果名称不一样，不能自动注入，只能通过@RequestParm注解，进行手动的映射

    //文件上传，第一件事文字存到数据库里(MyBatis),文件本身存储在磁盘里(IO)
   @RequestMapping("addBook")
   @ResponseBody
   
    public Map addBook(@RequestParam("title") String title, @RequestParam("desc") String desc, @RequestParam("price")Double price, @RequestParam("profile")CommonsMultipartFile file, HttpServletRequest request) {

       System.out.println("title="+title);
       System.out.println("Desc="+desc);
       System.out.println("price="+price);
       System.out.println("file="+file.getOriginalFilename());
       Mapmap=new HashMap<>();

       String filePath=request.getServletContext().getRealPath("uploads");
       System.out.println(filePath);
       File path=new File(filePath);
       if(!path.exists()){
           path.mkdirs();
       }
       //构造文件名，用户名+时间戳
       User user=((User)request.getSession().getAttribute("user"));
       String username;
       if(user!=null){
           username=user.getUserName();
       }else {
           username="";
       }
       long time = System.currentTimeMillis();
       String filename=username+'_'+time+'_'+file.getOriginalFilename();
       File fileUpload =new File(filePath,filename);

       //创建输入流和输出流

       try {
           InputStream is= file.getInputStream();
           OutputStream os= new FileOutputStream(fileUpload);
           byte[]buffer = new byte[1024];
           int len;
           System.out.println("size="+file.getSize());
           while ((len = is.read(buffer))!=-1){
               System.out.println("len="+len);
                   os.write(buffer,0,len);
           }
           is.close();
           os.close();
           map.put("error",0);
           map.put("status","success");
           map.put("message","上传文件成功");
       } catch (IOException e) {
           e.printStackTrace();
           map.put("error",-1);
           map.put("status","error");
           map.put("message","上传文件失败");
       }

       return map;
   }