Spring Boot Callback after client receives resource? - spring-boot

Question

I'm creating an endpoint using Spring Boot which executes a combination of system commands (java.lang.Runtime API) to generate a zip file to return to the client upon request, here's the code.
#GetMapping(value = "generateZipFile")
public ResponseEntity<Resource> generateZipFile(#RequestParam("id") Integer id) throws IOException {
org.springframework.core.io.Resource resource = null;
//generate zip file using commandline
resource = service.generateTmpResource(id);
return ResponseEntity.ok()
.header(HttpHeaders.CONTENT_TYPE, "application/zip")
.header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"randomFile.zip\"")
.body(resource);
//somehow delete generated file here after client receives it
}
I cannot keep stacking up the files on the server for obvious disk limit reasons, so I'm looking for a way to delete the files as soon as the client downloads them. Is there a solution in Spring Boot for this? I basically need to hook a callback that would do the cleanup after the user receives the resource.
I'm using Spring Boot 2.0.6

Answer 1

You can create a new thread but a best solution would be create a ThreadPoolExecutor in order to manage threads or also Scheduled annotation helps us.
new Thread() {
#Override
public void run() {
service.cleanup(id);
}
}.start();
UPDATED
A best answer, it would be using a Stack combine with Thread.
Here is the solution that I've done.
https://github.com/jjohxx/example-thread

Answer 2

I ended up using a HandlerInterceptorAdapter, afterCompletion was the callback I needed. The only challenge I had to deal with was passing through the id of the resource to cleanup, which I handled by adding a header in my controller method:
#GetMapping(value = "generateZipFile")
public ResponseEntity<Resource> genereateZipFile(#RequestParam("id") Integer id,
RedirectAttributes redirectAttributes) throws IOException {
org.springframework.core.io.Resource resource = myService.generateTmpResource(id);;
return ResponseEntity.ok()
.header(HttpHeaders.CONTENT_TYPE, "application/zip")
.header(MyInterceptor.TMP_RESOURCE_ID_HEADER, id.toString())
.header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"someFile.zip\"")
.body(resource);
}
The interceptor code:
#Component
public class MyInterceptor extends HandlerInterceptorAdapter {
public static final String TMP_RESOURCE_ID_HEADER = "Tmp-ID";
#Autowired
private MyService myService;
#Override
public void afterCompletion(HttpServletRequest request,
HttpServletResponse response,
Object handler,
Exception ex) {
if(response == null || !response.containsHeader(TMP_RESOURCE_ID_HEADER)) return;
String tmpFileId = response.getHeader(TMP_RESOURCE_ID_HEADER);
myService.cleanup(tmpFileId);
}
}
For more information about interceptors see here.