How to return File downloaded as DataBuffer - spring

Question

I am downloading a file like below:
private File downloadAndReturnFile(String fileId, String destination) {
log.info("Downloading file.. " + fileId);
Path path = Paths.get(destination);
Flux<DataBuffer> dataBuffer = webClient.get().uri("/the/download/uri/" + fileId + "").retrieve()
.bodyToFlux(DataBuffer.class)
.doOnComplete(() -> log.info("{}", fileId + " - File downloaded successfully"));
//DataBufferUtils.write(dataBuffer, path, StandardOpenOption.CREATE).share().block();
return ???? // What should I do here to return above DataBuffer as file?
}
How can I return the dataBuffer as a File? Or, how can I convert this dataBuffer to a File object?

Answer 1

You could use DataBufferUtils.write method. To do that, you should
instantiate a File object (maybe using fileId and destination) which is also the return value you want
create OutputStream or Path or Channels object from the File object
call DataBufferUtils.write(dataBuffer, ....).share().block() to write the DataBuffer into the file
viz. (all thrown exceptions are omitted),
...
File file = new File(destination, fileId);
Path path = file.toPath();
DataBufferUtils.write(dataBuffer, path, StandardOpenOption.CREATE).share().block();
return file;
Or,
...
Path path = Paths.get(destination);
DataBufferUtils.write(dataBuffer, path, StandardOpenOption.CREATE).share().block();
return path.toFile();

Answer 2

In case someone looking for a full code. Just sharing Tonny's solution to the fullest.
private File downloadAndReturnFile(String fileId, String destination) throws FileNotFoundException {
log.info("Downloading file.. " + fileId);
Flux<DataBuffer> dataBuffer = webClient.get().uri("/the/download/uri/" + fileId + "").retrieve()
.bodyToFlux(DataBuffer.class)
.doOnComplete(() -> log.info("{}", fileId + " - File downloaded successfully"));
Path path = Paths.get(destination);
DataBufferUtils.write(dataBuffer, path, StandardOpenOption.CREATE).share().block();
return path.toFile();
}