Java后台上传下载文件的几种方式

/*** 通过 HTTP PUT 请求将 JPG 照片上传至指定的腾讯云地址* 协议要求:* <p>* PUT /<ObjectKey> HTTP/1.1* Host: xxx.myqcloud.com //腾讯提供的Host地址* Authorization: Auth String //每个图片的上传token，有效期为订单下发开始24h* [Object Content] //二进制照片内容*/
public void uploadImage(String localImagePath) throws Exception {// 1.将照片上传至腾讯地图众包侧提供的云服务上try {File imageFile = new File(localImagePath);if (imageFile.exists()) {String url = "http://" + mapVendor.getHost() + mapVendorImageDetail.getBackUrl();HttpHeaders headers = new HttpHeaders();headers.set("Content-Type", "image/jpeg");headers.add("Host", mapVendor.getHost());headers.add("Authorization", mapVendorImageDetail.getBackAuth());restTemplate.put(url, new HttpEntity<Resource>(new FileSystemResource(imageFile), headers));}} catch (RestClientException e) {// 2.使用捕获异常来处理返回的非200的状态响应,如果非200则认定上传失败logger.error("send local image [" + localImagePath + "] to tencent error", e);}
}/*** 以流的方式下载* @param path 欲下载的文件的路径* @param response 响应内容**/
public void download(String path, HttpServletResponse response) {try {// path是指欲下载的文件的路径File file = new File(path);// 取得文件名String filename = file.getName();// 取得文件的后缀名String ext = filename.substring(filename.lastIndexOf(".") + 1).toUpperCase();// 获取下载文件的输入流InputStream inputStream = new BufferedInputStream(new FileInputStream(file));byte[] buffer = new byte[inputStream.available()];inputStream.read(buffer);inputStream.close();// 清空responseresponse.reset();// 重新设置responseresponse.setContentType("application/octet-stream");response.addHeader("Content-Disposition", "attachment;filename=" + new String(filename.getBytes()));response.addHeader("Content-Length", "" + file.length());// 写入下载文件的输出流OutputStream outputStream = new BufferedOutputStream(response.getOutputStream());outputStream.write(buffer);outputStream.flush();outputStream.close();} catch (IOException ex) {//TODO 记录日志并做相关业务}/*** 把网络上的图片保存到本地*/
public void downloadNet() throws Exception {// 下载网络文件int byteSum = 0;int byteRead;URL url = new URL("https://www.baidu.com/img/PCtm_d9c8750bed0b3c7d089fa7d55720d6cf.png");URLConnection conn = url.openConnection();InputStream inputStream = conn.getInputStream();FileOutputStream fileOutputStream = new FileOutputStream("c:/logo.gif");// 存放读取的字节byte[] buffer = new byte[1204];while ((byteRead = inputStream.read(buffer)) != -1) {byteSum += byteRead;System.out.println(byteSum);fileOutputStream.write(buffer, 0, byteRead);}
}/*** 把网络上的图片保存到本地并支持在线打开*/
public void downLoad(String filePath, HttpServletResponse response, boolean isOnLine) throws Exception {File f = new File(filePath);if (!f.exists()) {response.sendError(404, "File not found!");return;}BufferedInputStream br = new BufferedInputStream(new FileInputStream(f));byte[] buf = new byte[1024];int len = 0;response.reset(); // 非常重要if (isOnLine) { // 在线打开方式URL u = new URL("file:///" + filePath);response.setContentType(u.openConnection().getContentType());response.setHeader("Content-Disposition", "inline; filename=" + f.getName());// 文件名应该编码成UTF-8} else { // 纯下载方式response.setContentType("application/x-msdownload");response.setHeader("Content-Disposition", "attachment; filename=" + f.getName());}OutputStream out = response.getOutputStream();while ((len = br.read(buf)) > 0)out.write(buf, 0, len);br.close();out.close();}