Feign实现微服务间文件上传

在Spring Cloud 的Feign组件中并不支持文件的传输，会出现这样的错误提示：

feign.codec.EncodeException: class [Lorg.springframework.web.multipart.MultipartFile; is not a type supported by this encoder.
    at feign.codec.Encoder$Default.encode(Encoder.java:90) ~[feign-core-9.5.1.jar:na]
    at feign.form.FormEncoder.encode(FormEncoder.java:87) ~[feign-form-3.3.0.jar:3.3.0]
    at feign.form.spring.SpringFormEncoder.encode(SpringFormEncoder.java:64) ~[feign-form-spring-3.3.0.jar:3.3.0]

但是我们可以通过使用Feign的扩展包实现这个功能。

一. 示例介绍

服务名	端口号	角色
feign_upload_first	8100	feign服务提供者
feign_upload_second	8101	feign服务消费者

我们调用feign_upload_second的上传文件接口上传文件，feign_upload_second内部使用feign调用feign_upload_first实现文件上传。

二 、单文件上传

2.1 feign_upload_first服务提供者

文件上传的服务提供者接口比较简单，如下所示：

@SpringBootApplication
public class FeignUploadFirstApplication {
  @RestController
  public class UploadController {
    
    @RequestMapping(value = "/uploadFile",method = RequestMethod.POST, consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    public String handleFileUpload(@RequestPart(value = "file") MultipartFile file) {
      return file.getOriginalFilename();
    }
  }
  public static void main(String[] args) {
    SpringApplication.run(FeignUploadFirstApplication.class, args);
  }
}

2.2 feign_upload_second服务消费者

1. 增加扩展包依赖，依赖包不能太高级，会报错

       <dependency>
         <groupId>io.github.openfeign.form</groupId>
         <artifactId>feign-form</artifactId>
         <version>3.3.0</version>
       </dependency>
       <dependency>
         <groupId>io.github.openfeign.form</groupId>
         <artifactId>feign-form-spring</artifactId>
         <version>3.3.0</version>
       </dependency>
       <dependency>
         <groupId>commons-fileupload</groupId>
         <artifactId>commons-fileupload</artifactId>
         <version>1.3.3</version>
       </dependency>

2. 新增feign实现文件上传的配置类

   import feign.codec.Encoder;
   import feign.form.spring.SpringFormEncoder;
   import org.springframework.context.annotation.Bean;
   import org.springframework.context.annotation.Configuration;
   
   @Configuration
   public class FeignSupportConfig {
     @Bean
     public Encoder feignFormEncoder() {
       return new SpringFormEncoder();
     }
   }

3. feign远程调用接口

   @FeignClient(name = "file",url = "http://localhost:8100",configuration = FeignSupportConfig.class)
   public interface UploadService {
     @RequestMapping(value = "/uploadFile", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
     String handleFileUpload(@RequestPart(value = "file") MultipartFile file);
   }

4. 上传文件接口

   @RestController
   public class UploadController {
     @Autowired
     UploadService uploadService;
     
     @RequestMapping(value = "/uploadFile",method = RequestMethod.POST, consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
     public String handleFileUpload(@RequestPart(value = "file") MultipartFile file) {
       return uploadService.handleFileUpload(file);
     }
   }

   2.3 测试

   使用postman进行测试，可以正常上传文件