Feign文件上传

1. 在自己的文件上传服务中引入feign 提供的依赖

        <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>

2.编写文件上传controller

@RestController
@RequestMapping
@Slf4j
public class StorageController {

    @PostMapping(value = "/upload", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    @ResponseBody
    public String upload(@RequestParam("file") MultipartFile file) {

        return "";
    }
}

3.编写供其他服务调用的feignClient

需要自定义配置feign 的encoder来解码multipartFile提交

在FeignClientsConfiguration第74行可知feign默认的encoder配置是 SpringEncoder

   @Bean
	@ConditionalOnMissingBean
	public Encoder feignEncoder() {
		return new SpringEncoder(this.messageConverters);
	}

(1).第一种配置方式

@FeignClient(value = "ResourceService",
        path = "/resource/",
        configuration = ResourceClient.MultipartConfig.class)
public interface ResourceClient {
    @PostMapping(value = "/upload", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    Resource upload(@RequestPart("file") MultipartFile file);

    class MultipartConfig {
        @Bean
        public Encoder feignFormEncoder() {
            return new SpringFormEncoder();
        }
    }
}

使用@FeignClient的configuration来配置当前client的encoder
注意不要在此配置类上添加@configruation,否则会影响全局的encoder配置

这样的话只会修改当前Client的默认的encoder

(2).第二种配置方式

直接修改全局的Encoder

@FeignClient(value = "ResourceService",
        path = "/resource/")
public interface ResourceClient {
    @PostMapping(value = "/upload", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    Resource upload(@RequestPart("file") MultipartFile file);
}

@Configruation
public  class MultipartConfig {
        @Bean
        public Encoder feignFormEncoder(ObjectFactory<HttpMessageConverters> messageConverters) {
            return new SpringFormEncoder(new SpringEncoder(messageConverters));
        }
}

如果直接将默认的全局SpringEncoder替换为SpringFormEncoder的话，普通的请求可能会报xxx is not a type supported by this encoder 的异常。

查看SpringFormEncoder的源码可知SpringFormEncoder.encode()方法判断bodyType是不是multipartFile，不是的话就直接调用默认的Encode处理

默认的Encoder.Default.encode()只会判断bodyType是否是 String还是byte[] 否则就会报xxx is not a type supported by this encoder 的异常。

所以在将全局的Encoder替换为SpringFormEncoder时将SpringFormEncoder的默认的encoder设置为SpringEncoder