Spring MVC 和 WebFlux 上传文件

WebFlux 上传文件

- 1. 表单上传方式
- - 1.1 Spring MVC
  - 1.2 Spring WebFlux
- 2. 二进制流
- - 2.1 Spring MVC
  - 2.2 Spring WebFlux

开发环境：jdk 11
WebFlux：jdk 8+

1. 表单上传方式

1.1 Spring MVC

multipart大小限制

spring:
  servlet:
    multipart:
      max-file-size: 512MB
      max-request-size: 1024MB

controller

	private static final Path BASE_PATH = Paths.get("./uploads");

	@PostMapping("/uploadForm")
    public String uploadForm(@RequestPart("files") MultipartFile[] files) throws IOException {
        for (MultipartFile file : files) {
            String fileName = UUID.randomUUID() + "-" + file.getOriginalFilename();
            final Path path = BASE_PATH.resolve(fileName);
            try (InputStream inputStream = file.getInputStream()) {
                Files.write(path, inputStream.readAllBytes());
            }
        }
        // 处理上传的二进制数据
        return "success";
    }

客户端

    String url = "http://localhost:8080/upload";
    final File file = new File("D:\\test\\2023032201-205680e2622740b5bb888b7e4801ebf0.mp4");
    RestTemplate restTemplate = new RestTemplate();
    // 设置请求头和请求体
    HttpHeaders headers = new HttpHeaders();
    headers.setContentType(MediaType.MULTIPART_FORM_DATA);
    final Resource resource = new FileSystemResource(file);
    final MultiValueMap<String, Object> valueMap = new LinkedMultiValueMap<>();
    valueMap.add("files", resource);
    HttpEntity<MultiValueMap<String, Object>> requestEntity = new HttpEntity<>(valueMap, headers);
    ResponseEntity<String> responseEntity = restTemplate.postForEntity(url, requestEntity, String.class);
    System.out.println(responseEntity.getStatusCode());

1.2 Spring WebFlux

multipart大小限制

spring:
  codec:
    # DataBuffer方式
    max-in-memory-size: 512MB
  webflux:
    multipart:
      max-in-memory-size: 512MB
      # 默认非流式
      streaming: false

controller

    private static final Path BASE_PATH = Paths.get("./uploads");

    @PostMapping("/upload")
    public Mono<List<String>> upload(@RequestPart("files") Flux<FilePart> files) {
        return files.flatMap(filePart -> {
            String fileName = UUID.randomUUID() + "-" + filePart.filename();
            final Path path = BASE_PATH.resolve(fileName);
            final File dest = path.toFile();
            return filePart.transferTo(dest).thenReturn(dest.getName());
        }).collectList();
    }

或者

    private static final Path BASE_PATH = Paths.get("./uploads");

	// 不推荐此种方式（文件名丢失）
    @PostMapping("/upload")
    public Mono<List<String>> upload(@RequestPart("files") Flux<DataBuffer> files) {
        return files.flatMap(dataBuffer -> {
            String fileName = UUID.randomUUID() + ".dat";
            final Path path = BASE_PATH.resolve(fileName);
            return DataBufferUtils.write(Mono.just(dataBuffer), path, StandardOpenOption.CREATE)
                    .then(Mono.just(fileName))
                    .onErrorResume(ex -> {
                        log.error("上传失败", ex);
                        return Mono.just("fail: " + ex.getMessage());
                    });
        }).collectList();
    }

客户端

    String url = "http://localhost:8080/upload";
    final File file = new File("D:\\test\\2023032201-205680e2622740b5bb888b7e4801ebf0.mp4");
    final MediaType contentType = MediaType.MULTIPART_FORM_DATA;
    WebClient webClient = WebClient.builder().build();       
    webClient.post()
        .uri(url)
        .contentType(contentType)
        .body(BodyInserters.fromMultipartData("files", new FileSystemResource(file)))
        .exchangeToMono(response -> response.bodyToMono(String.class))
        .subscribe(System.out::println);

 	// 无限期等待结果（线上不允许使用）
    Thread.currentThread().join();

值得一说的是FilePart和FormFieldPart均继承自Part,两者是平级关系。需要说明的是，客户端传输的org.springframework.core.io.Resource file part 对应的并不一定是 FilePart类型，也有可能是FormFieldPart，两者最主要的区别是，FilePart可以取到原始的文件名，FormFieldPart无法取得原始的文件名，这也是合理的，因为Resource有个派生类ByteArrayResource是基于内存的不存在文件名。

@see org.springframework.http.client.MultipartBodyBuilder

请添加图片描述
[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-sgI2MMRo-1683793805127)(WebFlux 上传文件.assets/image-20230510172435334.png)]

2. 二进制流

文件名参数的上传可以以post请求的url参数（注意）的形式进行上传，也可以在请求头header上传输。

URL参数编解码：

js： encodeURI(str)

java： URLEncoder.encode(str, "UTF-8")和URLDecoder.decode(encodedStr, "UTF-8")

2.1 Spring MVC

服务端

	private static final Path BASE_PATH = Paths.get("./uploads");

	@PostMapping("/upload")
    public String upload(@RequestBody Resource resource) throws IOException {
        // 此处Resource类型一定是ByteArrayResource，哪怕客户端传输的是FileSystemResource
        String fileName = UUID.randomUUID() + ".dat";
        final Path path = BASE_PATH.resolve(fileName);
        try (InputStream inputStream = resource.getInputStream()) {
            Files.write(path, inputStream.readAllBytes());
        }
        // 处理上传的二进制数据
        return "success";
    }

或者

	private static final Path BASE_PATH = Paths.get("./uploads");

	@PostMapping("/upload")
    public String upload(@RequestBody byte[] bytes) throws IOException {
        String fileName = UUID.randomUUID() + ".dat";
        final Path path = BASE_PATH.resolve(fileName);
        Files.write(path, bytes);
        // 处理上传的二进制数据
        return "success";
    }

使用HttpHeaders.CONTENT_DISPOSITION请求头传输文件名

@PostMapping("/upload")
    public String upload(HttpServletRequest request, @RequestBody Resource resource) throws IOException {
        String originalFilename = extractFileName(request);
        String fileName;
        if (Objects.isNull(originalFilename)) {
            fileName =  UUID.randomUUID() + ".dat";
        } else {
            fileName =  UUID.randomUUID() + "-" + originalFilename;
        }
        final Path path = BASE_PATH.resolve(fileName);
        try (InputStream inputStream = resource.getInputStream()) {
            Files.write(path, inputStream.readAllBytes());
        }
        // 处理上传的二进制数据
        return "success";
    }

    /**
     * 从请求头提取文件名
     *
     * @param request 请求对象
     * @return 文件名
     */
    private String extractFileName(HttpServletRequest request) {
        final String disposition = request.getHeader(HttpHeaders.CONTENT_DISPOSITION);
        if (Objects.nonNull(disposition)) {
            Pattern pattern = Pattern.compile("filename=\"(.+)\"");
            Matcher matcher = pattern.matcher(disposition);
            if(matcher.find()) {
                return matcher.group(1);
            }
        }
        return null;
    }

客户端

    public static void main(String[] args) throws IOException {
        String url = "http://localhost:8080/upload";
        final File file = new File("D:\\test\\2023032201-205680e2622740b5bb888b7e4801ebf0.mp4");
        RestTemplate restTemplate = new RestTemplate();
        // 设置请求头和请求体
        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
        headers.set(HttpHeaders.CONTENT_DISPOSITION, String.format("attachment; filename=\"%s\"", file.getName()));
        try (FileInputStream inputStream = new FileInputStream(file)) {
            HttpEntity<ByteArrayResource> requestEntity = new HttpEntity<>(new ByteArrayResource(inputStream.readAllBytes()), headers);
            ResponseEntity<String> responseEntity = restTemplate.postForEntity(url, requestEntity, String.class);
            System.out.println(responseEntity.getStatusCode());
        }
    }

值得一说的是MultipartFile和Resource均继承自InputStreamSource,两者是平级关系，MultipartFile用于接受表单文件参数，而Resource可用于接受二进制文件流。

[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-YZSdIaoo-1683793805129)(WebFlux 上传文件.assets/image-20230511095308032.png)]

2.2 Spring WebFlux

    @PostMapping("/upload")
    public Mono<String> upload(@RequestBody Mono<Resource> resourceMono) {
        return resourceMono.flatMap(resource -> {
            String fileName = UUID.randomUUID() + ".dat";
            final Path path = BASE_PATH.resolve(fileName);
            try (InputStream inputStream = resource.getInputStream()) {
                Files.write(path, inputStream.readAllBytes());
            } catch (IOException e) {
                log.error("上传失败", e);
                return Mono.error(e);
            }
            return Mono.just(fileName);
        });
    }

或者

    @PostMapping("/upload")
    public Mono<String> upload(@RequestBody Mono<byte[]> bytesMono) {
        return bytesMono.flatMap(bytes -> {
            String fileName = UUID.randomUUID() + ".dat";
            final Path path = BASE_PATH.resolve(fileName);
            try {
                Files.write(path, bytes);
            } catch (IOException e) {
                log.error("上传失败", e);
                return Mono.error(e);
            }
            return Mono.just(fileName);
        });
    }

客户端

    String url = "http://localhost:8080/upload";
    final File file = new File("D:\\test\\2023032201-205680e2622740b5bb888b7e4801ebf0.mp4");
    final MediaType contentType = MediaType.APPLICATION_OCTET_STREAM;
    WebClient webClient = WebClient.builder().build();
    try (final FileInputStream inputStream = new FileInputStream(file)) {
        final InputStreamResource resource = new InputStreamResource(inputStream);
        final String encode = URLEncoder.encode(file.getName(), Charset.defaultCharset());
        webClient.post()
            .uri(url)
            .contentType(contentType)
            .header(HttpHeaders.CONTENT_DISPOSITION, String.format("attachment; filename=\"%s\"", encode))
            .body(BodyInserters.fromResource(resource))
            .exchangeToMono(response -> response.bodyToMono(String.class))
            .subscribe(System.out::println);
        // 无限期等待结果（线上不允许使用）
        Thread.currentThread().join();
    }

使用HttpHeaders.CONTENT_DISPOSITION请求头传输文件名

    @PostMapping("/upload")
    public Mono<String> upload(@RequestBody Mono<byte[]> bytesMono, ServerHttpRequest request) {
        return bytesMono.flatMap(bytes -> {
            String originalFilename = extractFileName(request);
            String fileName;
            if (Objects.isNull(originalFilename)) {
                fileName =  UUID.randomUUID() + ".dat";
            } else {
                final String decode = URLDecoder.decode(originalFilename, Charset.defaultCharset());
                fileName =  UUID.randomUUID() + "-" + decode;
            }
            final Path path = BASE_PATH.resolve(fileName);
            try {
                Files.write(path, bytes);
            } catch (IOException e) {
                log.error("上传失败", e);
                return Mono.error(e);
            }
            return Mono.just(fileName);
        });
    }

    /**
     * 从请求头提取文件名
     *
     * @param request 请求对象
     * @return 文件名
     */
    private String extractFileName(ServerHttpRequest request) {
        final String disposition = request.getHeaders().getFirst(HttpHeaders.CONTENT_DISPOSITION);
        if (Objects.nonNull(disposition)) {
            Pattern pattern = Pattern.compile("filename=\"(.+)\"");
            Matcher matcher = pattern.matcher(disposition);
            if(matcher.find()) {
                return matcher.group(1);
            }
        }
        return null;
    }