Spring WebFlux文件上传：不支持分段上传的415类型媒体

Question

I'm running into some issues handling a file upload using spring's reactive framework. I think I'm following the docs, but can't get away from this 415 / Unsupported Media Type issue.

My controller looks like below (as per the example here: https://docs.spring.io/spring/docs/current/spring-framework-reference/web-reactive.html#webflux-multipart-forms )

package com.test.controllers;

import reactor.core.publisher.Flux;

import org.springframework.http.MediaType;
import org.springframework.http.codec.multipart.FilePart;
import org.springframework.http.codec.multipart.Part;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class TestController {

    @RequestMapping(value = "/upload", method = RequestMethod.POST, consumes = MediaType.MULTIPART_FORM_DATA_VALUE, produces = MediaType.APPLICATION_JSON_VALUE)
    public Flux<String> uploadHandler(@RequestBody Flux<Part> parts) {
        return parts
                .filter(part -> part instanceof FilePart)
                .ofType(FilePart.class)
                .log()
                .flatMap(p -> Flux.just(p.filename()));
    }

}

POSTing to this endpoint though, always gives me the same output:

curl -X POST -F "data=@basic.ppt" http://localhost:8080/upload
---
"Unsupported Media Type","message":"Content type 'multipart/form-data;boundary=------------------------537139718d79303c;charset=UTF-8' not supported"

I've attempted to use @RequestPart("data") too, but get a similar Unsupported Media Type error, albeit with the content type of the file.

It seems that Spring is having issues converting these to a Part ..? I'm stuck - any help is apprecitated!

Answer 1

Well, it's not a direct answer for your question, because I use functional endpoints, but I hope it will help you somehow.

import org.springframework.context.annotation.Bean;
import org.springframework.http.codec.multipart.FilePart;
import org.springframework.http.codec.multipart.Part;
import org.springframework.stereotype.Controller;
import org.springframework.web.reactive.function.BodyExtractors;
import org.springframework.web.reactive.function.server.HandlerFunction;
import org.springframework.web.reactive.function.server.RouterFunction;
import org.springframework.web.reactive.function.server.ServerResponse;

import java.io.File;
import java.util.Map;

import static org.springframework.web.reactive.function.BodyInserters.fromObject;
import static org.springframework.web.reactive.function.server.RequestPredicates.POST;
import static org.springframework.web.reactive.function.server.RequestPredicates.path;
import static org.springframework.web.reactive.function.server.RouterFunctions.nest;
import static org.springframework.web.reactive.function.server.RouterFunctions.route;

@Controller
public class FileUploadController {

    @Bean
    RouterFunction<ServerResponse> apiRoutes() {
        return nest(path("/api"),
                route(POST("/upload"), fileUpload()));
    }

    private HandlerFunction<ServerResponse> fileUpload() {
        return request -> {
            return request.body(BodyExtractors.toMultipartData()).flatMap(parts -> {
                        Map<String, Part> map = parts.toSingleValueMap();
                        final FilePart filePart = (FilePart) map.get("file");
                        final String dir = "C:\\JDeveloper\\mywork\\Spring\\SpringTest\\webflux-file-upload\\uploaded";
                        filePart.transferTo(new File(dir + "/" + filePart.filename()));

                        return ServerResponse.ok().body(fromObject("ok, file uploaded"));
                    }
            );
        };
    }

}

You can upload a file with curl like this:

curl -F "file=@C:\Users\Wojtek\Desktop\img-5081775796112008742.jpg" localhost:8080/api/fileupload

Answer 2

Thanks @kojot for your answer, but in this case I discovered the issue was my inclusion of spring-webmvc transiently in addition to spring-webflux . Your solution would likely have worked too, but I wanted to stick with the Controller style so ended up forcibly excluding spring-webmvc from my build.gradle :

configurations {
    implementation {
        exclude group: 'org.springframework', module: 'spring-webmvc'
    }
}

After that it worked as documented.