spring webflux file upload and download

sequence

This article mainly describes the file upload and download of spring webflux.

maven

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-webflux</artifactId>
		</dependency>

File Upload

@PostMapping(value = "/upload", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    public Mono<String> requestBodyFlux(@RequestPart("file") FilePart filePart) throws IOException {
        System.out.println(filePart.filename());
        Path tempFile = Files.createTempFile("test", filePart.filename());

        //NOTE 方法一
        AsynchronousFileChannel channel =
                AsynchronousFileChannel.open(tempFile, StandardOpenOption.WRITE);
        DataBufferUtils.write(filePart.content(), channel, 0)
                .doOnComplete(() -> {
                    System.out.println("finish");
                })
            .subscribe();

        //NOTE 方法二
//        filePart.transferTo(tempFile.toFile());

        System.out.println(tempFile.toString());
        return Mono.just(filePart.filename());
    }

Use RequestPart to receive, the content of FilePart FilePart is Flux<DataBuffer>, you can use DataBufferUtils to write to the file or directly use transferTo to write to the file

document dowload

    @GetMapping("/download")
    public Mono<Void> downloadByWriteWith(ServerHttpResponse response) throws IOException {
        ZeroCopyHttpOutputMessage zeroCopyResponse = (ZeroCopyHttpOutputMessage) response;
        response.getHeaders().set(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=parallel.png");
        response.getHeaders().setContentType(MediaType.IMAGE_PNG);

        Resource resource = new ClassPathResource("parallel.png");
        File file = resource.getFile();
        return zeroCopyResponse.writeWith(file, 0, file.length());
    }

Here data is written to ServerHttpResponse

summary

Using webflux, there is no HttpServletRequest and HttpServletReponse based on the servlet container before, instead org.springframework.http.server.reactive.ServerHttpRequest and org.springframework.http.server.reactive.ServerHttpResponse.

doc

MultipartIntegrationTests