關於springcloud中使用feign出現LinkedHashMap can not be cast to xxx 的解決方案

• 個人公眾號
• 扯淡
• 解決方案 自定義FeignClient,覆蓋提供的FeignClient
• 最後

個人公眾號

扯淡

• 博主遇到這個問題也很久了,在網上也看了沒找到解決方案,一直沒時間去解決,最近稍微抽了一點時間研究了一下,分享出來造福眾多的碼農朋友,feign預設是根據返回的資料解析為LinkedHashMap這種key value的格式,但是我們專案中一般會有自定義的Result<T,E>這樣的複雜型別的物件,這樣的話,feign就不能像dubbo這樣的rpc那樣得到我們自己想要的Result<T,E>物件,下面是解決方案:

解決方案 自定義FeignClient,覆蓋提供的FeignClient

@Configuration
public class FeignConfig {

   @Bean
   public Decoder feignDecoder() {
       HttpMessageConverter jacksonConverter = new MappingJackson2HttpMessageConverter(objectMapper());
       ObjectFactory<HttpMessageConverters> objectFactory =
 
 () -> new HttpMessageConverters(jacksonConverter);
       return new ResponseEntityDecoder(new SpringDecoder(objectFactory));
   }
   @Bean
   public Encoder feignEncoder(){
       HttpMessageConverter jacksonConverter = new MappingJackson2HttpMessageConverter(objectMapper());
       ObjectFactory<
 
HttpMessageConverters> objectFactory = () -> new HttpMessageConverters(jacksonConverter);
       return new SpringEncoder(objectFactory);
   }
   public ObjectMapper objectMapper(){
       ObjectMapper objectMapper = new ObjectMapper();
       objectMapper.configure(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT, true);
       return objectMapper;
   }
}

• 再附上一段呼叫的程式碼 ,需要注意的是在介面上必須加上你需要轉化的結果,不然還是 LinkedHashMap

@FeignClient(value = "xxx-service",fallback = UserFacadeFallback.class)
@Component
public interface UserFacade {
    @RequestMapping(value = "/user", method = {RequestMethod.POST})
    UserResponse<EnumGeneralResultCode,UserDto> getUserDto(@RequestBody UserDto user);
}

最後

開始愉快的擼碼吧 !