springmvc模式下的上传和下载

接触了springmvc模式后，对上一次的上传与下载进行优化，

上次请看这里。

此处上传的功能依旧是采用表格上传。文件格式依旧是

    <form action="${pageContext.request.contextPath}/upload" method="post" enctype="multipart/form-data">

后台则是

 @RequestMapping("/upload")
    public String upload(MultipartFile file,String userName,HttpServletRequest request) throws IOException {
        String filename = file.getOriginalFilename();

        String suffix = filename.substring(filename.lastIndexOf("."));

        if(suffix.equalsIgnoreCase(".jpg")){
            String uuid = UUID.randomUUID().toString();
            //FileUtils.copyInputStreamToFile(file.getInputStream(),new File("E://"+uuid+suffix));

            file.transferTo(new File("D://"+System.currentTimeMillis()+suffix));//位置存储在硬盘上
//            file.transferTo(new File(request.getServletContext().getRealPath("/")+"static/userImages/"+file));
//            存储在项目里的目录下
            request.setAttribute("result","上传成功");
            return "/result.jsp";
        }else{
            request.setAttribute("result","上传失败");
            return "/result.jsp";
        }
    }

相比之前的传统式上传，springmvc模式下封装了许多繁琐的过程，通过transferTo即可实现一些相应的操作

而下载也是相应的简化了许多

@RequestMapping("/download")
    public void download(String filename, HttpServletResponse response, HttpServletRequest request) throws IOException {
        response.setHeader("content-disposition","attachment;filename="+filename);

        ServletOutputStream outputStream = response.getOutputStream();

        String path = request.getServletContext().getRealPath("images");

        File file = new File(path,filename);

        byte[] bytes = FileUtils.readFileToByteArray(file);

        outputStream.write(bytes);

        outputStream.close();
    }

一般框架会省去许多重复性的工作，但底层的基本原理还是要清楚过程