Springboot2.7 文件上传和下载

最新推荐文章于 2024-07-15 11:11:58 发布

工作这么多年，学会了内卷

最新推荐文章于 2024-07-15 11:11:58 发布

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文章标签： java 服务器后端

本文链接：https://blog.youkuaiyun.com/goPlayJava/article/details/136619443

版权

本文介绍了在Java中处理文件上传和下载的方法，包括如何使用`MultipartFile`处理上传文件，以及通过`@GetMapping(/download)`处理文件下载请求，对比了`outputStream.write()`和`outputStream.print()`的区别。

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1、文件上传

public R<String> uploadFile(MultipartFile files){
        LocalDate now = LocalDate.now();
        int month = now.getMonthValue();
        int year = now.getYear();
        int day = now.getDayOfMonth();
        String s = UUID.randomUUID().toString().replace("-","");
        String filename = s+files.getOriginalFilename().substring(files.getOriginalFilename().lastIndexOf("."));
        String returnFilename = year+"-"+month+"-"+day+"-"+filename;
        String filePath = uploadDir+"\\"+year+"\\"+month+"\\"+"\\"+day+"\\"+filename;
        File file = new File(filePath);
        if (!file.exists()){
            file.mkdirs();
        }

        try {
            files.transferTo(file);
        } catch (IOException e) {
            e.printStackTrace();
        }

        return R.success(returnFilename);

    }

2、文件下载

outputStream.write()

outputStream.print()

都可以将后端的数据响应的前端，但是仔细对比是有区别的，需要根据实际使用进行区分。

@GetMapping("/download")
    public void downloadFile(String name, HttpServletResponse response) throws IOException {

        String[] filename = name.split("-");
        String filePath = uploadDir+"/"+filename[0]+"/"+filename[1]+"/"+filename[2]+"/"+filename[3];

        File file = new File(filePath);
        if (file.exists()){
            byte[] bytes = new byte[1024];
            int read = 0;
            ServletOutputStream outputStream = response.getOutputStream();
            FileInputStream fis = new FileInputStream(file);
            response.setContentType("image/jpg");
            try {
                while ((read = fis.read(bytes)) != -1){
                    outputStream.write(bytes,0,read);
                    outputStream.flush();
                }
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }finally {
                outputStream.close();
                fis.close();
            }

        }else{
           
            response.setContentType("text/html;charset=utf-8");
      
            response.getWriter().write("<h1>文件不存在</h1>");
      
            response.setStatus(203);
        }


    }