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));
   }

}