java后台简单从阿里云下载文件通知前端以附件的形式保存

@Override
    public MessageVo getDownLoadFile(String fileName, String ossKey, HttpServletResponse response) {
// fileName :前台传入的文件名（主要是标识文件是什么格式.png或.zip）
// ossKey:上传文件时阿里云返回的标识
// 配置阿里云基本信息
 String aliyunId = ApplicationPropertyUtils.getContextProperty("ALIYUN_ACCESS_KEY_ID");  
            String aliyunSecret = ApplicationPropertyUtils.getContextProperty("ALIYUN_ACCESS_KEY_SECRET");  
            String ossEndpoint =  ApplicationPropertyUtils.getContextProperty("ALIYUN_OSS_ENDPOINT");  
            OSSClient ossClient  = new OSSClient(ossEndpoint, aliyunId, aliyunSecret);  

// 获取fileid对应的阿里云上的文件对象  
            OSSObject ossObject = ossClient.getObject(bucketName, ossKey);//bucketName需要自己设置  
           // 已缓冲的方式从字符输入流中读取文本，缓冲各个字符，从而提供字符、数组和行的高效读取
           BufferedReader reader = new BufferedReader(new    InputStreamReader(ossObject .getObjectContent()));
                  // 缓冲文件输出流
            BufferedOutputStream outputStream=new BufferedOutputStream(response.getOutputStream());
            // 通知浏览器以附件形式下载
            response.setHeader("Content-Disposition","attachment;filename="+ URLEncoder.encode(fileName,"UTF-8"));
            // 进行解码 为防止文件出现乱码 文件上传时进行编码处理
            BASE64Decoder base64Decoder = new BASE64Decoder();
          byte[] car;
           while (true) {
              String line = reader.readLine();
             if (line == null) break;
               car =  base64Decoder.decodeBuffer(line);
                outputStream.write(car);
            }

          reader.close();

            if(outputStream!=null){
                outputStream.flush();
                outputStream.close();
            }

        } catch (IOException e) {
            e.printStackTrace();
            message(" Backend file write error ！！！");
            return messageVo;

        } catch (OssException e){
          e.printStackTrace();
            message(" The file name or ossKey value is error ！！！");
            return messageVo;
        }
    }