背景：
原方案：关于文件上传下载接口，服务端生成对象存储的请求临时链返回给客户端，客户端使用临时链直接请求对象存储服务，进行上传、下载文件。
弊端：无法控制上传文件大小
同时客户场地的网络环境禁止办公网直接访问对象存储服务域名。
改造后：用户携带临时链参数请求服务端，服务端使用这些参数访问对象存储服务，将文件返回给用户。在服务端做代理请求。
问题：有一道代理，文件下载耗时问题
第一版下载接口代码
使用临时链下载文件，再返回响应。整个下载文件过程在服务内部静默，客户端无法感知。同时文件流处理耗时较长。
@GetMapping("/**")
public ResponseEntity<byte[]> downloadFile(HttpServletRequest request) {
log.info("url:{}, queryString:{}", request.getRequestURL(), request.getQueryString());
String url = request.getRequestURL().toString()+"?"+request.getQueryString();
log.info("url:{}",url);
String downloadUrl = url.replace(url.substring(0,url.indexOf(minioProperties.getBucketName())-1), minioProperties.getEndpoint());
log.info("downloadUrl:{}",downloadUrl);
Date startTime = new Date();
byte[] responseBytes = restTemplate.execute(
URI.create(downloadUrl),
HttpMethod.GET,
new RequestCallback() {
@Override
public void doWithRequest(ClientHttpRequest request) throws IOException {
// 清除默认的 Content-Type 请求头
request.getHeaders().remove("Content-Type");
}
},
new ResponseExtractor<byte[]>() {
@Override
public byte[] extractData(ClientHttpResponse response) throws IOException {
// 从响应中读取字节数组
InputStream inputStream = response.getBody();
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
byte[] buffer = new byte[10240];
int bytesRead;
while ((bytesRead = inputStream.read(buffer)) != -1) {
byteArrayOutputStream.write(buffer, 0, bytesRead);
}
return byteArrayOutputStream.toByteArray();
}
}
);
Date downTime = new Date();
log.info("downloadTime:{}",downTime.getTime()-startTime.getTime());
HttpHeaders responseHeaders = new HttpHeaders();
responseHeaders.setContentType(MediaType.APPLICATION_OCTET_STREAM);
responseHeaders.setContentDisposition(
ContentDisposition.builder("attachment")
.filename(UrlUtils.getFileNameFromUrl(request.getRequestURL().toString())) // 设置下载文件的名称
.build()
);
Date returnTime = new Date();
log.info("responseTime:{}",returnTime.getTime()-downTime.getTime());
return new ResponseEntity<>(responseBytes, responseHeaders, HttpStatus.OK);
}
第二版下载接口代码
直接将下载的响应返回给客户端，消除了文件流处理的耗时，但是等待服务端下载完成的耗时仍然没有解决，且下载过程客户端没有感知。
@GetMapping("/**")
public ResponseEntity<Resource> downloadFile(HttpServletRequest request) {
log.info("url:{}, queryString:{}", request.getRequestURL(), request.getQueryString());
String url = request.getRequestURL().toString() + "?" + request.getQueryString();
log.info("url:{}", url);
String downloadUrl = url.replace(url.substring(0, url.indexOf(minioProperties.getBucketName()) - 1), minioProperties.getEndpoint());
log.info("downloadUrl:{}", downloadUrl);
HttpHeaders responseHeaders = new HttpHeaders();
responseHeaders.setContentType(MediaType.APPLICATION_OCTET_STREAM);
responseHeaders.setContentDisposition(
ContentDisposition.builder("attachment")
.filename(UrlUtils.getFileNameFromUrl(request.getRequestURL().toString())) // 设置下载文件的名称
.build()
);
// 获取文件大小，如果不可用，则设置为未知长度
long contentLength = getContentLength(request.getRequestURL().toString());
log.info("contentLength:{}", contentLength);
responseHeaders.setContentLength(contentLength);
Date startTime = new Date();
ResponseEntity<Resource> responseEntity = storageRestTemplate.execute(
URI.create(downloadUrl),
HttpMethod.GET,
requestCallback -> requestCallback.getHeaders().remove("Content-Type"),
response -> {
InputStream inputStream = response.getBody();
byte[] bytes = IOUtils.toByteArray(inputStream);
return ResponseEntity.ok()
.headers(responseHeaders)
.body(new InputStreamResource(new ByteArrayInputStream(bytes)));
}
);
Date downTime = new Date();
log.info("downloadTime:{}", downTime.getTime() - startTime.getTime());
log.info("responseTime:{}", downTime.getTime() - startTime.getTime());
return responseEntity;
}
第三版下载接口代码
使用minioClient获取对象的GetObjectResponse,这是一个inputSream，使用这个inputStream返回ResponseEntity
@GetMapping("/**")
public ResponseEntity<InputStreamResource> downloadFile(HttpServletRequest request) throws MinioException {
try {
log.info("url:{}, queryString:{}", request.getRequestURL(), request.getQueryString());
String url = request.getRequestURL().toString() + "?" + request.getQueryString();
log.info("url:{}", url);
String downloadUrl = url.replace(url.substring(0, url.indexOf(minioProperties.getBucketName()) - 1), minioProperties.getEndpoint());
log.info("downloadUrl:{}", downloadUrl);
//尝试用下载链接下载文件
if (!checkUrlSafety(downloadUrl)) {
log.error("下载链接{}不合法", downloadUrl);
return ResponseEntity.status(403).build();
}
//从链接中获取对象存储信息
String[] urlArr = request.getRequestURL().toString().split("/");
if (urlArr.length < 3) {
//未知长度
return ResponseEntity.badRequest().build();
}
String bucketName = urlArr[urlArr.length - 3];
String objectId = urlArr[urlArr.length - 2] + "/" + urlArr[urlArr.length - 1];
//通过minioClient获取响应流
GetObjectResponse getObjectResponse = minioUtil.getObject(bucketName, objectId);
InputStream inputStream = (InputStream) getObjectResponse;
//设置下载文件名
HttpHeaders headers = new HttpHeaders();
headers.add(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=" + UrlUtils.getFileNameFromUrl(request.getRequestURL().toString()));
//获取文件大小
long contentLength = minioUtil.statObject(bucketName, objectId).size();
return ResponseEntity.ok()
.headers(headers)
.contentType(MediaType.APPLICATION_OCTET_STREAM)
.contentLength(contentLength)
.body(new InputStreamResource(inputStream));
} catch (Exception e) {
return ResponseEntity.status(500).body(null);
}
}
/**
* 校验链接安全
* @param urlToCheck
* @return
*/
private boolean checkUrlSafety(String urlToCheck) {
try {
URL url = new URL(urlToCheck);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
int responseCode = connection.getResponseCode();
if (responseCode == HttpURLConnection.HTTP_OK) {
//响应code为200
return true;
}
} catch (IOException e) {
System.out.println("Error checking URL: " + e.getMessage());
}
return false;
}
客户端感知：
当返回为文件流输出时播放器会直接有加载进度条，不会需要等较长时间一次性加载完成。可以直接进行播放，不需要等文件下载完成。
针对较大文件，点击下载时直接会有下载进度，不再等待很长时间。
这里需要注意content-length大小设置，否则进度条无法预测。