How to Enable File Upload with Spring Cloud Feign: A Step‑by‑Step Guide

Service Provider (File Receiver)

Implementation uses standard Spring MVC annotations to accept multipart/form‑data requests.

@EnableFeignClients
@EnableDiscoveryClient
@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        new SpringApplicationBuilder(Application.class).web(true).run(args);
    }
}

@RestController
public class UploadController {
    @PostMapping(value = "/uploadFile", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    public String handleFileUpload(@RequestPart(value = "file") MultipartFile file) {
        return file.getName();
    }
}

Service Consumer (File Sender)

Add the following Maven dependencies to enable Feign multipart support.

<dependency>
    <groupId>io.github.openfeign.form</groupId>
    <artifactId>feign-form</artifactId>
    <version>3.0.3</version>
</dependency>
<dependency>
    <groupId>io.github.openfeign.form</groupId>
    <artifactId>feign-form-spring</artifactId>
    <version>3.0.3</version>
</dependency>
<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.3.3</version>
</dependency>

Define the Feign client and a configuration class that supplies a multipart‑capable encoder.

@EnableFeignClients
@EnableDiscoveryClient
@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        new SpringApplicationBuilder(Application.class).web(true).run(args);
    }
}

@FeignClient(value = "upload-server", configuration = UploadService.MultipartSupportConfig.class)
public interface UploadService {
    @PostMapping(value = "/uploadFile", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    String handleFileUpload(@RequestPart(value = "file") MultipartFile file);
}

@Configuration
public class MultipartSupportConfig {
    @Bean
    public Encoder feignFormEncoder() {
        return new SpringFormEncoder();
    }
}

Test Case

A JUnit test creates a MultipartFile from a local file and invokes the Feign client.

@Slf4j
@RunWith(SpringJUnit4ClassRunner.class)
@SpringBootTest
public class UploadTester {
    @Autowired
    private UploadService uploadService;

    @Test
    @SneakyThrows
    public void testHandleFileUpload() {
        File file = new File("upload.txt");
        DiskFileItem fileItem = (DiskFileItem) new DiskFileItemFactory()
                .createItem("file", MediaType.TEXT_PLAIN_VALUE, true, file.getName());

        try (InputStream input = new FileInputStream(file);
             OutputStream os = fileItem.getOutputStream()) {
            IOUtils.copy(input, os);
        }

        MultipartFile multipart = new CommonsMultipartFile(fileItem);
        log.info(uploadService.handleFileUpload(multipart));
    }
}

Full Example

The complete source code can be cloned from the following repositories:

GitHub: https://github.com/dyc87112/SpringCloud-Learning/

Gitee: https://gitee.com/didispace/SpringCloud-Learning/