英文:
Rest template read response as stream and pass to spring controller(Get InputStream with rest Template)
问题
我有一个下载大型zip文件的URL。它以流的形式返回响应。尽管文件大小很大,但首先会返回200(HTTP状态码为OK),然后继续下载。
我必须实现一个新的Spring控制器,通过RestTemplate调用上述URL。我必须读取RestTemplate返回的响应,并传递给控制器。最初我是这样实现的:
@GetMapping("/export/downloadFile")
public ResponseEntity<byte[]> downloadData(Model model,
@ModelAttribute(EXCEPTION_COLLECTOR) ExceptionCollector exceptionCollector,
@RequestParam("userName") String userName,
@RequestParam("startDate") Date startDate,
@RequestParam("endDate") Date endDate,
@RequestParam("reason") String reason) {
URI uri = // 构建URL;
return restTemplate.exchange(uri, HttpMethod.GET, new HttpEntity<>(httpHeaders), byte[].class);
}
因为我使用了ResponseEntity<byte[]>,RestTemplate会等待整个文件加载到内存中。因此,我经常遇到套接字超时问题。
我们是否有方法以流的形式读取响应并返回给控制器?
我找到了一些关于restTemplate.execute的内容。
restTemplate.execute(uri, HttpMethod.GET, requestCallBack, clientHttpResponse -> {
File ret = File.createTempFile("download", ".zip", new File("/Users/bokkavijay/Desktop"));
StreamUtils.copy(clientHttpResponse.getBody(), new FileOutputStream(ret));
return ret;
});
上面的代码片段可以将文件复制到本地而不会超时,但这不是我想要的。
我们如何将clientHttpResponse中的流导入到控制器中?
英文:
I have a url which download the large size zip file.It returns the response as stream.though file size is large first it returns 200(HTTPSTATUK.OK) and continues download.
I have to implement a new spring controller which call the above url through rest template.I have to read the response returned by rest template and pass to controller.initially I have implemented in below way
@GetMapping("/export/downloadFile")
public ResponseEntity<byte[]> downloadData(Model model,
@ModelAttribute(EXCEPTION_COLLECTOR) ExceptionCollector exceptionCollector,
@RequestParam("userName") String userName,
@RequestParam("startDate") Date startDate,
@RequestParam("endDate") Date endDate,
@RequestParam("reason") String reason) {
URI uri = /building url here/;
return restTemplate.exchange(uri, HttpMethod.GET, new HttpEntity<>(httpHeaders), byte[].class);
}
since I am using ResponseEntity<byte[]> , rest template waits till entire file loaded into memory.so very frequently I am getting socket timeout issue.
Do we have way to read the response as stream and return to controller.
I found few things about restTemplate.execute .
restTemplate.execute(uri,HttpMethod.GET,requestCallBack,clientHttpResponse -> {
File ret = File.createTempFile("download", ".zip",new File("/Users/bokkavijay/Desktop"));
StreamUtils.copy(clientHttpResponse.getBody(), new FileOutputStream(ret));
return ret;
});
above snippet can copy the file to our local with out time out but this is not what I need.
how can we pipe the stream in clientHttpResponse to controller ?
答案1
得分: 0
我找到了可工作的实现方式。
控制器:
@GetMapping("/readResponseAsStream")
public ResponseEntity<StreamingResponseBody> downloadAsStream(Model model, HttpServletResponse response) {
HttpHeaders httpHeaders = new HttpHeaders();
httpHeaders.add("Transfer-Encoding", "chunked");
httpHeaders.add("Content-Type", "x-zip-compressed");
httpHeaders.add("Content-Disposition", "attachment;filename=sample.zip");
ServletOutputStream servletOutputStream = response.getOutputStream();
StreamingResponseBody downloadFile = out -> {
RequestCallback requestCallBack = request -> {
// 在这里添加请求头
request.getHeaders().add(/*添加请求头内容*/);
};
ResponseExtractor<ServletOutputStream> responseExtractor = clientHttpResponse -> {
// 如果你想将响应流写入 HttpServletResponse,可以在这里添加代码片段
byte[] buff = new byte[800000];
int bytesRead = 0;
while ((bytesRead = clientHttpResponse.getBody().read(buff)) != -1) {
servletOutputStream.write(buff, 0, bytesRead);
}
return servletOutputStream;
// 如果你想要将文件复制到本地
File ret = File.createTempFile("download", ".zip", new File("在这里添加本地系统目录地址"));
StreamUtils.copy(clientHttpResponse.getBody(), new FileOutputStream(ret));
// 你可以将 clientHttpResponse.getBody() 复制到 ByteArrayInputStream 并返回
// 不要直接返回 clientHttpResponse.getBody(),因为 RestTemplate 在 .execute 完成后会关闭 inputStream(clientHttpResponse.getBody())
// 如果你想要在 DAO 层中编写 restTemplate.execute,将 servletOutputStream 作为参数传递给方法
};
restTemplate.execute(URL_ADDRESS, HttpMethod.GET, requestCallBack, responseExtractor);
};
return new ResponseEntity(downloadFile, httpHeaders, HttpStatus.OK);
}
如果你将响应直接写入 HttpServletResponse,当我们在浏览器中访问时,控制器会下载该文件。
英文:
I found the working implementation
Controller
@GetMapping("/readResponseAsStream")
public ResponseEntity<StreamingResponseBody> downloadAsStream(Model model,HttpServletResponse response) {
HttpHeaders httpHeaders=new HttpHeaders();
httpHeaders.add("Transfer-Encoding","chunked");
httpHeaders.add("Content-Type","x-zip-compressed");
httpHeaders.add("Content-Disposition", "attachment;filename=sample.zip");
ServletOutputStream servletOutputStream=response.getOutputStream();
StreamingResponseBody downloadFile = out -> {
RequestCallback requestCallBack=request->{
request.getHeaders().add(//Add headers here);
};
ResponseExtractor<ServletOutputStream> responseExtractor = clientHttpResponse -> {
//code snippet if you want to write response stream to HttpServletResponse
byte[] buff = new byte[800000];
int bytesRead = 0;
while ((bytesRead = clientHttpResponse.getBody().read(buff)) != -1) {
servletOutputStream.write(buff, 0, bytesRead);
}
return servletOutputStream;
//Incase if you want to copy file to you local
File ret = File.createTempFile("download", ".zip",new File("Add Local system directory address here"));
StreamUtils.copy(clientHttpResponse.getBody(), new FileOutputStream(ret));
//You can copy the the clientHttpResponse.getBody() to ByteArrayInputStream and return
// Don't return clientHttpResponse.getBody() directly because rest template will close the inputStream(clientHttpResponse.getBody()) after .execute completed
//if you want to write restTemplate.execute in dao layer , pass servletOutputStream as a argument to method
};
restTemplate.execute(URL_ADDRESS,HttpMethod.GET,requestCallBack,responseExtractor);
};
return new ResponseEntity(downloadFile,httpHeaders,HttpStatus.OK);
}
If you write the response directly to HttpServletResponse , controller download the file when we access in browser
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