@Configuration
@EnableScheduling
@EnableDiscoveryClient
@EnableFeignClients(value = {"com.ts"})
@MapperScan(value = {"com.ts.xx.xx"}, nameGenerator = FullBeanNameGenerator.class)
public class xxxxAutoConfig {
}

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
@Import(FeignClientsRegistrar.class)
public @interface EnableFeignClients {}

class FeignClientsRegistrar
    implements ImportBeanDefinitionRegistrar, ResourceLoaderAware, EnvironmentAware {}
  @Override
  public void registerBeanDefinitions(AnnotationMetadata metadata,
      BeanDefinitionRegistry registry) {
    registerDefaultConfiguration(metadata, registry);
    registerFeignClients(metadata, registry);
  }  

public void registerFeignClients(AnnotationMetadata metadata,
            BeanDefinitionRegistry registry) {
        //創(chuàng)建一個(gè)類掃描器
        ClassPathScanningCandidateComponentProvider scanner = getScanner();
        scanner.setResourceLoader(this.resourceLoader);
        Set<String> basePackages;
        //獲取EnableFeignClients注解包含的屬性
        Map<String, Object> attrs = metadata
                .getAnnotationAttributes(EnableFeignClients.class.getName());
        //這是一個(gè)FeignClient注解過(guò)濾器
        AnnotationTypeFilter annotationTypeFilter = new AnnotationTypeFilter(
                FeignClient.class);
        final Class<?>[] clients = attrs == null ? null
                : (Class<?>[]) attrs.get("clients");
        //準(zhǔn)備出待掃描的路徑
        if (clients == null || clients.length == 0) {
            scanner.addIncludeFilter(annotationTypeFilter);
            basePackages = getBasePackages(metadata);
        }
        else {
            final Set<String> clientClasses = new HashSet<>();
            basePackages = new HashSet<>();
            for (Class<?> clazz : clients) {
                basePackages.add(ClassUtils.getPackageName(clazz));
                clientClasses.add(clazz.getCanonicalName());
            }
            AbstractClassTestingTypeFilter filter = new AbstractClassTestingTypeFilter() {
                @Override
                protected boolean match(ClassMetadata metadata) {
                    String cleaned = metadata.getClassName().replaceAll("\\$", ".");
                    return clientClasses.contains(cleaned);
                }
            };
            scanner.addIncludeFilter(
                    new AllTypeFilter(Arrays.asList(filter, annotationTypeFilter)));
        }
        for (String basePackage : basePackages) {
        //先掃描出含有@FeignClient注解的類
            Set<BeanDefinition> candidateComponents = scanner
                    .findCandidateComponents(basePackage);
            for (BeanDefinition candidateComponent : candidateComponents) {
                if (candidateComponent instanceof AnnotatedBeanDefinition) {
                    // verify annotated class is an interface
                    AnnotatedBeanDefinition beanDefinition = (AnnotatedBeanDefinition) candidateComponent;
                    AnnotationMetadata annotationMetadata = beanDefinition.getMetadata();
                    //該類必須是接口，做強(qiáng)制校驗(yàn)
                    Assert.isTrue(annotationMetadata.isInterface(),
                            "@FeignClient can only be specified on an interface");
                    //獲取該類的所有屬性
                    Map<String, Object> attributes = annotationMetadata
                            .getAnnotationAttributes(
                                    FeignClient.class.getCanonicalName());
                    //獲取服務(wù)名稱
                    String name = getClientName(attributes);
                    registerClientConfiguration(registry, name,
                            attributes.get("configuration"));
                    //循環(huán)對(duì)使用@FeignClient注解的不同的類，做工廠bean注冊(cè)
                    registerFeignClient(registry, annotationMetadata, attributes);
                }
            }
        }
    }
    private void registerFeignClient(BeanDefinitionRegistry registry,
            AnnotationMetadata annotationMetadata, Map<String, Object> attributes) {
        //含有@FeignClient該類的名稱
        String className = annotationMetadata.getClassName();
        //創(chuàng)建一個(gè)BeanDefinitionBuilder，內(nèi)含AbstractBeanDefinition，指定待創(chuàng)建的Bean的名字是FeignClientFactoryBean
        BeanDefinitionBuilder definition = BeanDefinitionBuilder
                .genericBeanDefinition(FeignClientFactoryBean.class);
        validate(attributes);
        definition.addPropertyValue("url", getUrl(attributes));
        definition.addPropertyValue("path", getPath(attributes));
        String name = getName(attributes);
        definition.addPropertyValue("name", name);
        definition.addPropertyValue("type", className);
        definition.addPropertyValue("decode404", attributes.get("decode404"));
        definition.addPropertyValue("fallback", attributes.get("fallback"));
        definition.addPropertyValue("fallbackFactory", attributes.get("fallbackFactory"));
        definition.setAutowireMode(AbstractBeanDefinition.AUTOWIRE_BY_TYPE);
        String alias = name + "FeignClient";
        AbstractBeanDefinition beanDefinition = definition.getBeanDefinition();
        boolean primary = (Boolean)attributes.get("primary"); // has a default, won't be null
        beanDefinition.setPrimary(primary);
        String qualifier = getQualifier(attributes);
        if (StringUtils.hasText(qualifier)) {
            alias = qualifier;
        }
        BeanDefinitionHolder holder = new BeanDefinitionHolder(beanDefinition, className,
                new String[] { alias });
        //動(dòng)態(tài)注冊(cè)
        BeanDefinitionReaderUtils.registerBeanDefinition(holder, registry);
    }
    //BeanDefinitionReaderUtils.registerBeanDefinition
    public static void registerBeanDefinition(
            BeanDefinitionHolder definitionHolder, BeanDefinitionRegistry registry)
            throws BeanDefinitionStoreException {
        // Register bean definition under primary name.
        String beanName = definitionHolder.getBeanName();
        //BeanDefinitionRegistry.registerBeanDefinition實(shí)現(xiàn)具體的注冊(cè),會(huì)告知他需要注冊(cè)的類名、以及AbstractBeanDefinition
        registry.registerBeanDefinition(beanName, definitionHolder.getBeanDefinition());
        // Register aliases for bean name, if any.
        String[] aliases = definitionHolder.getAliases();
        if (aliases != null) {
            for (String alias : aliases) {
                registry.registerAlias(beanName, alias);
            }
        }
    }

@Override
  public Object getObject() throws Exception {
    return getTarget();
  }
  <T> T getTarget() {
    FeignContext context = applicationContext.getBean(FeignContext.class);
    Feign.Builder builder = feign(context);
    //先校驗(yàn)基礎(chǔ)屬性，基礎(chǔ)屬性是在FeignClientsRegistrar中給動(dòng)態(tài)Bean，添加屬性addPropertyValue時(shí)候賦值的
    //URL為空，則使用http://serviceName的方式拼接
    if (!StringUtils.hasText(this.url)) {
      String url;
      if (!this.name.startsWith("http")) {
        url = "http://" + this.name;
      }
      else {
        url = this.name;
      }
      url += cleanPath();
      //創(chuàng)建動(dòng)態(tài)的代理對(duì)象，采用JDK動(dòng)態(tài)代理
      return (T) loadBalance(builder, context, new HardCodedTarget<>(this.type,
          this.name, url));
    }
    //含有url，也就是FeignClient的注解接口里是一個(gè)絕對(duì)地址
    if (StringUtils.hasText(this.url) && !this.url.startsWith("http")) {
      this.url = "http://" + this.url;
    }
    String url = this.url + cleanPath();
    Client client = getOptional(context, Client.class);
    if (client != null) {
      if (client instanceof LoadBalancerFeignClient) {
        // not load balancing because we have a url,
        // but ribbon is on the classpath, so unwrap
        client = ((LoadBalancerFeignClient)client).getDelegate();
      }
      builder.client(client);
    }
    Targeter targeter = get(context, Targeter.class);
    return (T) targeter.target(this, builder, context, new HardCodedTarget<>(
        this.type, this.name, url));
  }

@Override
    public Response execute(Request request, Options options) throws IOException {
      HttpURLConnection connection = convertAndSend(request, options);
      return convertResponse(connection).toBuilder().request(request).build();
    }

public Response execute(Request request, Request.Options options) throws IOException {
    try {
      URI asUri = URI.create(request.url());
      String clientName = asUri.getHost();
      URI uriWithoutHost = cleanUrl(request.url(), clientName);
      FeignLoadBalancer.RibbonRequest ribbonRequest = new FeignLoadBalancer.RibbonRequest(
          this.delegate, request, uriWithoutHost);
      IClientConfig requestConfig = getClientConfig(options, clientName);
      return lbClient(clientName).executeWithLoadBalancer(ribbonRequest,
          requestConfig).toResponse();
    }
    catch (ClientException e) {
      IOException io = findIOException(e);
      if (io != null) {
        throw io;
      }
      throw new RuntimeException(e);
    }
  }

cloud-provider.ribbon.ConnectTimeout = 500 //請(qǐng)求連接的超時(shí)時(shí)間。
cloud-provider.ribbon.ReadTimeout = 2000  //請(qǐng)求處理的超時(shí)時(shí)間。
cloud-provider.ribbon.OkToRetryOnAllOperations = true //對(duì)所有操作請(qǐng)求都進(jìn)行重試。
cloud-provider.ribbon.MaxAutoRetriesNextServer = 2 //切換實(shí)例的重試次數(shù)。
cloud-provider.ribbon.MaxAutoRetries = 1 //對(duì)當(dāng)前實(shí)例的重試次數(shù)。

logging.level.com.wuzz.demo.HelloService = DEBUG

@Bean
Logger.Level feignLoggerLevel() {
    return Logger.Level.FULL;
}

@Configuration
public class FullLogConfiguration {
@Bean
Logger.Level feignLoggerLevel() {
    return Logger.Level.FULL;
}
@FeignClient(name = "cloud-provider", configuration = FullLogConfiguration.class)
public interface TestService {
}

@Component
public class HystrixClientService implements FallbackFactory<ClientService> {
    @Override
    public ClientService create(Throwable throwable) {
        return new ClientService() {
            @Override
            public String test() {
                return "test sdfsdfsf";
            }
        };
    }
}

@FeignClient(value ="cloud-provider", fallbackFactory = HystrixClientService.class)
public interface ClientService {
    @RequestMapping(value ="/test",method= RequestMethod.GET)
    String test() ;
}

feign:
   hystrix:
    enabled: true