环境:

spring boot: 2.3.4.RELEASE
java: 1.8

消费者

maven依赖

<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>

参数配置

spring.application.name=consumer-application
server.port=8082

eureka.client.register-with-eureka=true
eureka.client.serviceUrl.defaultZone=http://localhost:8080/eureka

启动类

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
public class ConsumerApplication {

    public static void main(String[] args){
        SpringApplication.run(ConsumerApplication.class, args);
    }
}

Feign 接口 (以下参考网络资料)

@FeignClient(value = "hello-service", configuration = HelloWorld.MultipartSupportConfig.class)
public interface HelloWorld {

    @PostMapping(value = "/upload/file", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    String upload(MultiValueMap<String, Object> multiValueMap);

    class MultipartSupportConfig{

        @Bean
        @Primary
        @Scope("prototype")
        public Encoder feignFormEncoder(ObjectFactory<HttpMessageConverters> converters) {
            return new SpringFormEncoder(new SpringEncoder(converters));
        }
    }
}

Controller

@Controller
@Slf4j
public class UploadController {

    @Autowired
    private HelloWorld helloWorld;

    @PostMapping("/upload/file")
    public String upload(UploadBO uploadBO) {

        File tempFile = null;
        try{
          tempFile = Files.createTempFile("galaxy_file_temp",uploadBO.getFile().getOriginalFilename()).toFile();
            uploadBO.getFile().transferTo(tempFile);
        } catch (IOException ex) {
            ex.printStackTrace();
        }
        FileSystemResource fileSystemResource = new FileSystemResource(tempFile);
        log.info("file name is : {}", uploadBO.getFileName());
        MultiValueMap<String, Object> multiValueMap = new LinkedMultiValueMap<>();
        multiValueMap.add("file", fileSystemResource);
        multiValueMap.add("fileName", uploadBO.getFileName());
        multiValueMap.add("fileSize", uploadBO.getFileSize());
        return helloWorld.upload(multiValueMap);

提供者

Controller

@Controller
@Slf4j
public class UploadController {

    @PostMapping("/upload/file")
    public String upload(UploadBO uploadBO) {
      log.info("file name is : {}", uploadBO.getFileName());
        File tempFile = null;
        try{
            tempFile = Files.createTempFile("galaxy_file_temp",uploadBO.getFile().getOriginalFilename()).toFile();
            log.info("{}", tempFile.getAbsolutePath());
            uploadBO.getFile().transferTo(tempFile);
        } catch (IOException ex) {
            ex.printStackTrace();
        }
      return "success";
    }
}

@Data
public class UploadBO {

    private String fileName;

    private Integer fileSize;

    private MultipartFile file;
}

---

以上测试通过，但移到公司项目上时却无法成功，经反复测试是由于公司项目上一个服务有多个client，当针对同一个服务的某个feign client配置configuration时，configuration未能生效，由于公司项目不便升级故使用restTemplate发送请求。

https://www.jianshu.com/p/e94fc3ca3295

HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.MULTIPART_FOMR_DATA);
HttpEntity requestEntity = new HttpEntity(multiValueMap, headers);
restTemplate.postForEntity(url, requestEntity, JSONObject.class, new Object[0]);