序

本文主要讲述一下spring webflux的文件上传和下载。

maven

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

文件上传

@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来接收，得到的是FilePart

FilePart的content是Flux<DataBuffer>，可以使用DataBufferUtils写到文件

或者直接使用transferTo写入到文件

文件下载

    @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());
    }

这里将数据写入ServerHttpResponse

小结

使用webflux就没有之前基于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