在Spring Cloud封装的Feign中并不直接支持传文件，但可以通过引入Feign的扩展包来实现，本文就来具体说说如何实现。
服务提供方（接收文件）
服务提供方的实现比较简单，就按Spring MVC的正常实现方式即可，比如：
@EnableFeignClients@EnableDiscoveryClient@SpringBootApplicationpublic class Application { @RestController public class UploadController { @PostMapping(value = "/uploadFile", consumes = MediaType.MULTIPART_FORM_DATA_VALUE) public String handleFileUpload(@RequestPart(value = "file") MultipartFile file) { return file.getName(); } } public static void main(String[] args) { new SpringApplicationBuilder(Application.class).web(true).run(args); }}
服务消费方（发送文件）
在服务消费方由于会使用Feign客户端，所以在这里需要在引入feign对表单提交的依赖，具体如下：
<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>
定义文件上传方的应用主类和FeignClient，假设服务提供方的服务名为 eureka-feign-upload-server
@EnableFeignClients@EnableDiscoveryClient@SpringBootApplicationpublic 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 class MultipartSupportConfig { @Bean public Encoder feignFormEncoder() { return new SpringFormEncoder(); } }}
在启动了服务提供方之后，尝试在服务消费方编写测试用例来通过上面定义的Feign客户端来传文件，比如：
@Slf4j@RunWith(SpringJUnit4Cla***unner.class)@SpringBootTestpublic 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); } catch (Exception e) { throw new IllegalArgumentException("Invalid file: " + e, e); } MultipartFile multi = new CommonsMultipartFile(fileItem); log.info(uploadService.handleFileUpload(multi)); }}
完整示例：
读者可以根据喜好选择下面的两个仓库中查看 eureka-feign-upload-server和 eureka-feign-upload-client两个项目：
Github：https://github.com/dyc87112/SpringCloud-Learning/
Gitee：https://gitee.com/didispace/SpringCloud-Learning/