###spring mvc 文件上传下载

####上传

• 用MultipartFile来上传文件，上传到本地指定路径下

• controller:

  @RequestMapping(value = "/upload")  @ResponseBody  public String upload(@RequestParam("file") MultipartFile file,  	@RequestParam("type") Integer type, HttpServletRequest request,  	HttpServletResponse response) {  	Preconditions.checkNotNull(type);  	Preconditions.checkNotNull(file);  	Preconditions.checkArgument(file.getSize() < Constants.FILE_MAX_SIZE);  	Preconditions.checkArgument(Constants.FILE_TYPE_MAP.containsKey(type));  	if (!this.validate(file)) {  		return JsonReply.newItem().failed().toJson();  	}  	String path = request.getSession().getServletContext().getRealPath("/");  	Long fileId = fileService.saveFile(file, type, path);  	if (fileId.equals(Constants.ERROR_LONG)) {  		return JsonReply.newItem().failed().toJson();  	}  	JsonReply reply = JsonReply.newItem();  	reply.addObject("id", fileId);  	return reply.success().toJson();  }

type是对类型做一个分类，不同类别放到不同文件夹下

• service:

  @Override  public Long saveFile(@NonNull MultipartFile multipartFile, Integer type,  	String path) {  	// TODO Auto-generated method stub  	String originalName = multipartFile.getOriginalFilename();  	// String fileDir = path + originalName;  	String fileDir = Constants.FILE_DIR + Constants.FILE_TYPE_MAP.get(type)  			+ originalName;  	final File file = new File(fileDir);  	try {  		Files.write(multipartFile.getBytes(), file);  	} catch (IOException e) {  		// TODO: handle exception  		log.info("save file error,{}", e);  		return Constants.ERROR_LONG;  	}  	FileBo fileBo = new FileBo();  	fileBo.setUrl(originalName);  	fileBo.setType(type);  	fileDao.saveFileInfo(fileBo);  	return fileBo.getId();

  }

• 前端：

    
        
                              上传文件：        
                   	
         类别      
             
         
            
                 
        
      
          
              

#####下载

• 用HttpServletResponse来下载，但是不是最好的选择，今后改

• controller:

  @RequestMapping(value = "/download/{id}")  public void file(@PathVariable Long id, HttpServletResponse resp)  	throws IOException {  	OutputStream output = resp.getOutputStream();  	Preconditions.checkNotNull(id);  	FileBo file = fileService.getFileBo(id);  	if (file == null) {  		return;  	}  	String disposition = "attachment;filename=" + file.getUrl();  	resp.reset();  	resp.setHeader("Content-Disposition", disposition);  	resp.setContentType("application/octet-stream; charset=utf-8");  	try {  		fileService.download(file, output);  	} catch (IOException e) {  		// TODO: handle exception  		log.info("FileController.file failed.[{e}]", e);  	} finally {  		IOUtils.closeQuietly(output);  	}  }

• service

  @Override  public void download(FileBo file, OutputStream output) throws IOException {  	// TODO Auto-generated method stub  	String fileDir = Constants.FILE_DIR  			+ Constants.FILE_TYPE_MAP.get(file.getType()) + file.getUrl();  	final File downloadFile = new File(fileDir);  	output.write(FileUtils.readFileToByteArray(downloadFile));  }