Spring Cloud Feign的文件上传实现

      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，本来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
      @SpringBootApplication
      public 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
      @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
      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(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);
      } catch (Exception e) {
      throw new IllegalArgumentException("Invalid file: " + e, e);
      }
      MultipartFile multi = new CommonsMultipartFile(fileItem);
      log.info(uploadService.handleFileUpload(multi));
      }
      }