WebFlux：上传文件时出现问题

Question

我正在开发一个客户端来使用 webflux 反应客户端上传文件：这是我的客户端代码：private Mono<String> postDocument(String authorization, InputStream content) {    try {        ByteArrayResource resource = new ByteArrayResource(IOUtils.toByteArray(content));        return client.post().uri(DOCS_URI)                .contentType(MediaType.MULTIPART_FORM_DATA)                .header(HttpHeaders.AUTHORIZATION, authorization)                .body(BodyInserters.fromMultipartData("file", resource))                .exchange()                .flatMap(res -> readResponse(res, String.class));    } catch (IOException e) {        throw new RuntimeException(e);    }}服务器端代码：    public Mono<ServerResponse> createDocument(ServerRequest request) {    return request.body(toMultipartData())            .flatMap(parts -> Mono.just((FilePart) parts.toSingleValueMap().get("file")))            .flatMap(part -> {                try {                    String fileId = IdentifierFactory.getInstance().generateIdentifier();                    File tmp = File.createTempFile(fileId, part.filename());                    part.transferTo(tmp);                    String documentId = IdentifierFactory.getInstance().generateIdentifier();                    String env = request.queryParam("env")                            .orElse("prod");                    CreateDocumentCommand cmd = new CreateDocumentCommand(documentId, tmp, part.filename(), env);                    return Mono.fromFuture(cmdGateway.send(cmd));                } catch (IOException e) {                    throw new RuntimeException(e);                }            })            .flatMap(res -> ok().body(fromObject(res)));}我得到这个错误：java.lang.ClassCastException: org.springframework.http.codec.multipart.SynchronossPartHttpMessageReader$SynchronossPart cannot be cast to org.springframework.http.codec.multipart.FilePart

Answer 1

我有示例代码，但在 Kotlin 中。

我希望它能帮助你。

第一种方式（节省内存）

upload(stream: InputStream, filename: string): HashMap<String, Any> {

        val request: MultiValueMap<String, Any> = LinkedMultiValueMap();

        request.set("file", MultipartInputStreamFileResource(stream, filename))

        return client.post().uri("http://localhost:8080/files")

            .contentType(MediaType.MULTIPART_FORM_DATA)

            .body(BodyInserters.fromMultipartData(request))

            .awaitExchange().awaitBody()

}

class MultipartInputStreamFileResource(inputStream: InputStream?, private val filename: String) : InputStreamResource(inputStream!!) {

        override fun getFilename(): String? {

            return filename

        }

        @Throws(IOException::class)

        override fun contentLength(): Long {

            return -1 // we do not want to generally read the whole stream into memory ...

        }

}

第二种方式

//You wrote a file to somewhere in the controller then send the file through webclient

upload(stream: InputStream, filename: string): HashMap<String, Any> {

        val request: MultiValueMap<String, Any> = LinkedMultiValueMap();

        request.set("file", FileSystemResource(File("/tmp/file.jpg")))

        return client.post().uri("http://localhost:8080/files")

            .contentType(MediaType.MULTIPART_FORM_DATA)

            .body(BodyInserters.fromMultipartData(request))

            .awaitExchange().awaitBody()

}

第三种方式

upload(file: Part): HashMap<String, Any> {

        val request: MultiValueMap<String, Any> = LinkedMultiValueMap();

        request.set("file", file)

        return client.post().uri("http://localhost:8080/files")

            .contentType(MediaType.MULTIPART_FORM_DATA)

            .body(BodyInserters.fromMultipartData(request))

            .awaitExchange().awaitBody()

}

Answer 2

这对我有用

MultipartBodyBuilder bodyBuilder = new MultipartBodyBuilder();

bodyBuilder.part("file", new ClassPathResource("/bulk_upload/test.xlsx"));

List<DataFileAdjustment> list = webClient.post().uri("/bulk").accept(MediaType.APPLICATION_JSON)

        .body(BodyInserters.fromMultipartData(bodyBuilder.build()))

        .exchange()

        .expectStatus().isOk()