java下载网络文件

/*** 下载文件** @param fileId* @param response* @throws Exception*/
@GetMapping("/downLoadFile")
public void downLoadFile(Long fileId, HttpServletResponse response) throws Exception{// 根据文件ID查询文件路径FileDO fileDO = fileService.get(fileId);// 定义一个URL对象，就是你想下载的图片的URL地址URL url = new URL(fileDO.getUrl());// 打开连接HttpURLConnection conn = (HttpURLConnection) url.openConnection();// 设置请求方式为"GET"conn.setRequestMethod("GET");// 超时响应时间为10秒conn.setConnectTimeout(10 * 1000);// 通过输入流获取图片数据InputStream is = conn.getInputStream();// 得到图片的二进制数据，以二进制封装得到数据，具有通用性byte[] data = readInputStream(is);// 创建一个文件对象用来保存图片String[] filePathArr = fileDO.getPath().split("\\/");String fileUrl = rootUrl+"/"+filePathArr[filePathArr.length-1];File imageFile = new File(fileUrl);// 创建输出流FileOutputStream outStream = new FileOutputStream(imageFile);// 写入数据outStream.write(data);// 关闭输出流，释放资源outStream.close();BufferedInputStream bins = new BufferedInputStream(new FileInputStream(imageFile));response.setCharacterEncoding("UTF-8");response.setHeader("content-Type", "application/x-download");response.setHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(imageFile.getName(), "UTF-8"));ServletOutputStream out = null;try {// 这边直接在浏览器下载out = response.getOutputStream();int bytesRead = 0;byte[] buffer = new byte[8192];while ((bytesRead = bins.read(buffer, 0, 8192)) != -1) {out.write(buffer, 0, bytesRead);}out.flush();bins.close();out.close();FileUtil.deleteFile(fileUrl);// 删除文件} catch (IOException e) {e.printStackTrace();}
}

public static byte[] readInputStream(InputStream inStream) throws Exception {ByteArrayOutputStream outStream = new ByteArrayOutputStream();// 创建一个Buffer字符串byte[] buffer = new byte[6024];// 每次读取的字符串长度，如果为-1，代表全部读取完毕int len;// 使用一个输入流从buffer里把数据读取出来while ((len = inStream.read(buffer)) != -1) {// 用输出流往buffer里写入数据，中间参数代表从哪个位置开始读，len代表读取的长度outStream.write(buffer, 0, len);}// 关闭输入流inStream.close();// 把outStream里的数据写入内存return outStream.toByteArray();
}