1:创建Feign接口定义

@FeignClient(name = "user-service",configuration = UserServiceFeignClientConfiguration.class)
public interface UserRegistrationService {

    @PostMapping(value = "/user/register", produces = "application/json;v=3") // V3
    Boolean registerUser(@RequestBody @Validated @Valid User user);

}

2:创建项目bootstrap启动类

@EnableAutoConfiguration
@EnableFeignClients(clients = UserRegistrationService.class )
@LoadBalancerClient(name = "user-service",configuration = UserServiceLoadBalanceConfiguration.class)
public class FeignClientSpringBootstrap {

    public static void main(String[] args) {
        ConfigurableApplicationContext context
                = new SpringApplicationBuilder(FeignClientSpringBootstrap.class).web(WebApplicationType.NONE)
                .build().
                run(args);


        UserRegistrationService userRegistrationService = context.getBean(UserRegistrationService.class);

        User user = new User();
        user.setId(2L);
        user.setName("test");
        Boolean res = userRegistrationService.registerUser(user);

        System.out.println("res==="+res);
        context.close();
    }
}

3:创建loadbalance配置类UserServiceLoadBalanceConfiguration

@Configuration
public class UserServiceLoadBalanceConfiguration {


    @Bean
    public ReactorLoadBalancer<ServiceInstance> randomLoadBalancer(Environment environment, LoadBalancerClientFactory loadBalancerClientFactory){
        String name = environment.getProperty(LoadBalancerClientFactory.PROPERTY_NAME);
        return new RandomLoadBalancer(loadBalancerClientFactory.getLazyProvider(name, ServiceInstanceListSupplier.class),name);
    }


    @Bean
    public ServiceInstanceListSupplier serviceInstanceListSupplier(){
        return new UserServiceServiceInstanceListSupplier();
    }

}

参考官方文档链接

image.png

4:创建UserServiceServiceInstanceListSupplier类返回loadbalance调用那个服务实列

public class UserServiceServiceInstanceListSupplier implements ServiceInstanceListSupplier {
    @Override
    public String getServiceId() {
        return "user-service";
    }

    @Override
    public Flux<List<ServiceInstance>> get() {
        return Flux.just(Arrays.asList(getLocalServiceInstance()));
    }

    private ServiceInstance getLocalServiceInstance(){
        DefaultServiceInstance instance = new DefaultServiceInstance();

        instance.setInstanceId("user-service");
        instance.setHost("127.0.0.1");
        instance.setPort(8091);
        return instance;
    }
}

5:创建Feign处理Response类ApiResponseDecoder

public class ApiResponseDecoder implements Decoder {

    private final  Decoder decoder;

    public ApiResponseDecoder(Decoder decoder) {
        this.decoder = decoder;
    }

    @Override
    public Object decode(Response response, Type type) throws IOException, DecodeException, FeignException {
       String contentType = getContentType(response);

       MediaType mediaType = MediaType.parseMediaType(contentType);

       String version = mediaType.getParameter("v");

       if(version == null){

           Object object = decoder.decode(response, ApiResponse.class);

           if(object instanceof ApiResponse){
               return ApiResponse.class.cast(object).getBody();
           }

       }
        return decoder.decode(response,type);
    }

    private String getContentType(Response response){
        Collection<String> types=response.headers().getOrDefault("Content-Type", Arrays.asList(""));
        return types.iterator().next();
    }
}

6:配置ApiResponseDecoder

@Configuration
public class UserServiceFeignClientConfiguration {


    @Autowired
    private  ObjectFactory<HttpMessageConverters> messageConverters;


    @Bean
    public Decoder feignDecoder(){
        return new ApiResponseDecoder(new ResponseEntityDecoder(new SpringDecoder(messageConverters)));
    }

}

7:运行结果

image.png

8:代码执行逻辑

EnableFeignClients:启动Feign配置，生成代理对象UserRegistrationService
LoadBalancerClient(name = "user-service",configuration = UserServiceLoadBalanceConfiguration.class):
配置Feign远程调用时候loadbalance配置，如果没有配置，走默认配置

@FeignClient(name = "user-service",configuration = UserServiceFeignClientConfiguration.class):
配置Feign返回处理Response信息

github代码