spring springboot webflux 文件上传下载

webflux 的文件上传下载功能

文件上传

RestController架构

webflux直接提供了RequestPart注解,让我们拿到上传的文件数据

@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());
    return Mono.just(filePart.filename());
}

说明:使用RequestPart来接收,得到的是FilePart
FilePart的content是Flux,可以使用DataBufferUtils写到文件或者直接使用transferTo写入到文件

Route Handler架构

很多时候,我们使用 router 如下指定接口访问入口

@Bean
    RouterFunction<ServerResponse> myRouter(IndustryChainHandler icHandler) {
        return nest(
                path("/v2.0/mynetwork"),
                route(POST("/upload"), myHandler::upload));
}

此时不方便直接拿到RequestPart 数据,但是其实数据都还是在ServerRequest里面,变换一下就可以了。

public Mono<ServerResponse> upload(ServerRequest request) {
        return ok().contentType(APPLICATION_JSON_UTF8).body(
                request.body(BodyExtractors.toMultipartData()).map(parts -> {
                    Map<String, Part> map = parts.toSingleValueMap();
                    // ‘files’ 为客户端上传文件key
                    FilePart filePart = (FilePart) map.get("files");
                    try {
                        // 第一个参数是上传文件的前缀,可以随便起名字
                        Path tempFile = Files.createTempFile("upload_file", filePart.filename());
                        File dest = tempFile.toFile();
                        filePart.transferTo(dest);
                        return filePart.filename();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                    return "";
                }).map(filename -> {
                    if (!StringUtils.isEmpty(filename)) {
                        return "OK";
                    } else {
                        return "error";
                    }
                }), String.class
        );

文件下载

方法1:

@GetMapping("/download")
public Mono<Void> downloadByWriteWith(ServerHttpResponse response) throws IOException {
	ZeroCopyHttpOutputMessage zeroCopyResponse = (ZeroCopyHttpOutputMessage) response;
	response.getHeaders().set(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=myimage.png");
	response.getHeaders().setContentType(MediaType.IMAGE_PNG);
	Resource resource = new ClassPathResource("parallel.png");
	File file = resource.getFile();
	return zeroCopyResponse.writeWith(file, 0, file.length());
}

方法2:

@GetMapping("/download")
public Mono<ServerResponse> downloadByWriteWith(ServerRequest request) throws IOException {
	Resource resource = new ClassPathResource("myimage.png");
	return ok().header("Content-Disposition", "attachment; filename=myimage.png")
	.body(BodyInserters.fromResource(resource)).switchIfEmpty(Mono.empty());
}

说明:两种方法都是将数据写入ServerHttpResponse,方法2可以在配合path.route使用

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