mysql文件上传下载 vue下载

JAVA文件以流的形式存在Mysql(blob)数据库,mysql最大支持4G文件(longblb)

直接将流转换为byte存入数据库

public Response uploadBlob(MultipartFile file) {
    //数据库实体类 改成自己的
    FileUpload fileUpload = new FileUpload();
    fileUpload.setFileName(file.getOriginalFilename());
    try {
        fileUpload.setContent(FileTypeUtils.input2byte(file.getInputStream()));
    } catch (IOException e) {
        e.printStackTrace();
    }
    save(fileUpload);
    return Response.ok("成功", fileUpload.getId());
}


/**
 * 将 流 转换为byte
 *
 * @param inStream
 * @return
 * @throws IOException
 */
public static byte[] input2byte(InputStream inStream) throws IOException {
    try (ByteArrayOutputStream swapStream = new ByteArrayOutputStream()) {
        byte[] buff = new byte[inStream.available()];
        while (inStream.read(buff) != -1) {
            swapStream.write(buff);
        }
        return swapStream.toByteArray();
    } catch (Exception e) {
        e.printStackTrace();
    }
    return null;
}

下载文件输出文件流到前端

public void getFile(String id, HttpServletRequest request, HttpServletResponse response) throws UnsupportedEncodingException {
       // 获取数据库文件信息
       FileUpload fileUpload = getById(id);
       if (fileUpload.getContent() != null) {
           //获取存储的文件名称
           String filename = fileUpload.getFileName();
           //获取浏览器版本
           String userAgent = request.getHeader("USER-AGENT");
           //IE浏览器
           if (StringUtils.contains(userAgent, "MSIE")) {
               filename = URLEncoder.encode(filename, "UTF8");
           }
           //google,火狐浏览器
           else if (StringUtils.contains(userAgent, "Mozilla")) {
               filename = new String(filename.getBytes(), "ISO8859-1");
           }
           //其他浏览器
           else {
               filename = URLEncoder.encode(filename, "UTF8");
           }
           try {
               byte[] fileStream = fileUpload.getContent();
               response.setHeader("content-type", "application/octet-stream");
               //这边可以设置文件下载时的名字，我这边用的是文件原本的名字，可以根据实际场景设置
               response.setContentType("application/octet-stream");
               response.setHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(filename, "UTF-8"));
               OutputStream toClient = new BufferedOutputStream(response.getOutputStream());
               toClient.write(fileStream);
               toClient.flush();
               toClient.close();
           } catch (Exception e) {
               e.printStackTrace();
           }
       }
   }

流的方式前端要指定 responseType: ‘blob’

methods: {
   downLoad() {
     if (this.fileId) {
       request({
         url: "localhost:8080/file/getFile",
         method: "get",
         params: { id: this.fileId },
         //指定 responseType
         responseType: 'blob'
       }).then((resp) => {
         let blob = new Blob([resp],{
           type:'application/vnd.ms-excel'
         });
         let objectUrl = URL.createObjectURL(blob);  //生成一个url
         this.downloadFile(objectUrl,this.form.fileName)
       });
     }
   }
}

转成文件

public File getFile(String id, HttpServletRequest request, HttpServletResponse response) {
      // 获取数据库文件信息
      FileUpload fileUpload = getById(id);
      if (fileUpload.getContent() != null) {
          File file = null;
          try {
              file = new File(fileUpload.getFileName());
              if (!file.exists()) {
                  file.createNewFile();
              }
              OutputStream os = new FileOutputStream(file);
              os.write(fileUpload.getContent());
              os.close();
          } catch (Exception e) {
              e.printStackTrace();
          }
          return file;
      }
  }