【代码笔记】一种http方式下载文件且支持重试的方法

一种http方式下载文件且支持重试的方法

   /**
     * http下载 ossFileUrl
     *
     * @param ossFileUrl 文件url
     * @param path       下载到哪个目录 dir
     * @param f          文件名称 如aaa.txt
     * @return boolean true 成功 ; false 失败
     */
    private boolean httpDownloadOssFileUrl(String ossFileUrl, String path, String f) {
        log.info("http下载文件-ossUrl:{}", ossFileUrl);
        log.info("http下载文件-目标path:{}", path);
        log.info("http下载文件-目标file:{}", f);

        int maxRetries = 3;
        int retries = 0;
        boolean success = false;
        while (retries < maxRetries && !success) {
            log.info("第{}次下载!", retries + 1);
            try {
                //新建URL对象
                URL url = new URL(ossFileUrl);
                //文件对象，注意，并不是在本地创建一个文件，仅仅是一个文件对象
                File file = new File(path, f);
                //开启连接
                HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
                //UA是帮助网站识别当前访问的浏览器
                httpURLConnection.setRequestProperty("User-Agent", "NetFox");
                int responseCode = httpURLConnection.getResponseCode();
                log.info("responseCode:{}", responseCode);
                if (responseCode == HttpURLConnection.HTTP_OK) {
                    success = true;
                    //获得输入流
                    InputStream inputStream = httpURLConnection.getInputStream();
                    //文件输出流
                    try(FileOutputStream outputStream = new FileOutputStream(file)){
                        byte[] b = new byte[1024];
                        int nRead;
                        while ((nRead = inputStream.read(b, 0, 1024)) > 0) {
                            outputStream.write(b, 0, nRead);
                        }
                        log.info("OSS文件:{}下完了！", ossFileUrl);
                        inputStream.close();
                    }catch (Exception e){
                        log.error("下载oss文件失败", e);
                    }
                }
            } catch (Exception e) {
                log.error("下载oss文件失败-ossUrl:{}", ossFileUrl);
                log.error("下载oss文件失败", e);
            }
            retries++;
        }
        return success;
    }