文件下载:
@RequestMapping("/download")
	public ResponseEntity<byte []> download(HttpSession session){
		//获得当前项目
		ServletContext application = session.getServletContext();
		InputStream in = application.getResourceAsStream("/static/video/文件名.mp4");
		byte[] body;
		try {
			body = new byte[in.available()];
			//读取文件数据
			in.read(body);
			//关流
			in.close();
			HttpHeaders headers = new HttpHeaders();
			//告诉浏览器下载内容的信息 下载内容的格式
			headers.add("Context-Type",application.getMimeType("/static/video/文件名.mp4"));
			headers.add("Content-Disposition","attachment; filename=11-书城第三阶段-注册.mp4");
			
			//创建ResponseEntity对象
			ResponseEntity<byte[]> responseEntity = new ResponseEntity<byte[]>(body,headers,HttpStatus.OK);
			
			//返回entity对象
			return responseEntity;
		} catch (IOException e) {
			e.printStackTrace();
		}
			//如果下载失败 返回一个null
			return null;
	}
文件上传:
@RequestMapping(value="/upload")
	public String upload(String username,MultipartFile photo) {
		System.out.println("username");
		try {
			photo.transferTo(new File("e:\\image\\"+photo.getOriginalFilename()));
		} catch (IllegalStateException | IOException e) {
			e.printStackTrace();
		}
		return "upload_success";
	}
原文:https://www.cnblogs.com/m-ming/p/11679972.html