spring webflux文件上傳下載

序

本文主要講述一下spring webflux的文件上傳和下載。

maven

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

文件上傳

@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());
    }

使用RequestPart來接收，獲得的是FilePart
FilePart的content是Flux<DataBuffer>，可使用DataBufferUtils寫到文件
或者直接使用transferTo寫入到文件

文件下載

@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());
    }

這裏將數據寫入ServerHttpResponse

小結

使用webflux就沒有以前基於servlet容器的HttpServletRequest及HttpServletReponse了，取而代之的是org.springframework.http.server.reactive.ServerHttpRequest以及org.springframework.http.server.reactive.ServerHttpResponse。

doc

• MultipartIntegrationTests