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package com.example.microservice2;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;

@SpringBootApplication
@EnableDiscoveryClient //开启注册服务
@EnableFeignClients(defaultConfiguration = FeignClientConfiguration.class) //开启feign消费服务
public class DemoApplication {
	public static void main(String[] args) {
		SpringApplication.run(DemoApplication.class, args);
	}
}

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package com.example.microservice2;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;

@FeignClient(value = "microservice1", fallback = HelloServiceHystric.class, configuration = FeignClientConfiguration.class) // 访问微服务1，指定断路器类
public interface HelloService {
    @RequestMapping(value = "/hello", method = RequestMethod.GET)
    String hello(@RequestParam(value = "name") String name);
}

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@RefreshScope // 开启配置更新
@RestController
@Slf4j
public class HelloController {
    @Value("${serviceName}") // 读配置文件的这个属性
    private String serviceName;

    @RequestMapping("/hello")
    @HystrixCommand(fallbackMethod = "helloError", commandProperties = {
            @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "4000") }) // 指定断路器方法，断路器监控用
    public String hello(HttpServletRequest request, @RequestParam(value = "name", defaultValue = "Hugo") String name)
 throws InterruptedException {
        log.info("ServerName:{} time:{}", request.getServerName(),
                DateFormatUtils.format(new Date(), "yyyyMMdd HH:mm:ss"));
        TimeUnit.SECONDS.sleep(4);
        return "hello " + name + ", my name is " + serviceName;
    }

    public String helloError(HttpServletRequest request, String name) {
        return "microservice1 hystrix," + name + "!";
    }
}

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package com.example.microservice2;

@FeignClient(value = "microservice1", fallback = HelloServiceHystric.class, configuration = FeignClientConfiguration.class) // 访问微服务1，指定断路器类
public interface HelloService {
    @RequestMapping(value = "/hello", method = RequestMethod.GET)
    String hello(@RequestParam(value = "name") String name);
}

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public interface SetterFactory {

  /**
 * Returns a hystrix setter appropriate for the given target and method
 */
  HystrixCommand.Setter create(Target<?> target, Method method);

  /**
 * Default behavior is to derive the group key from {@link Target#name()} and the command key from
 * {@link Feign#configKey(Class, Method)}.
 */
  final class Default implements SetterFactory {

    @Override
    public HystrixCommand.Setter create(Target<?> target, Method method) {
      String groupKey = target.name();
      String commandKey = Feign.configKey(target.type(), method);
      return HystrixCommand.Setter
          .withGroupKey(HystrixCommandGroupKey.Factory.asKey(groupKey))
          .andCommandKey(HystrixCommandKey.Factory.asKey(commandKey));
    }
  }
}

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# 全局配置
ribbon:
 # 服务最大重试次数,不包含第一次请求，默认0
 MaxAutoRetries: 5
 # 负载均衡切换次数,如果服务注册列表小于 nextServer count 那么会循环请求 A > B >　A，默认1
 MaxAutoRetriesNextServer: 3
 #是否所有操作都进行重试
 OkToRetryOnAllOperations: false
 #连接超时时间，单位为毫秒，默认2秒
 ConnectTimeout: 3000
 #读取的超时时间，单位为毫秒，默认5秒
 ReadTimeout: 3000
# 实例配置
clientName:
  ribbon:
   MaxAutoRetries: 5
   MaxAutoRetriesNextServer: 3
   OkToRetryOnAllOperations: false
   ConnectTimeout: 3000
   ReadTimeout: 3000

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public class LoadBalancerFeignClient implements Client {

	static final Request.Options DEFAULT_OPTIONS = new Request.Options();

	IClientConfig getClientConfig(Request.Options options, String clientName) {
		IClientConfig requestConfig;
		if (options == DEFAULT_OPTIONS) {
			requestConfig = this.clientFactory.getClientConfig(clientName);
		}
		else {
			requestConfig = new FeignOptionsClientConfig(options);
		}
		return requestConfig;
	}
}

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public interface Retryer extends Cloneable {

  class Default implements Retryer {
      
	/**
 * Calculates the time interval to a retry attempt. <br>
 * The interval increases exponentially with each attempt, at a rate of nextInterval *= 1.5
 * (where 1.5 is the backoff factor), to the maximum interval.
 *
 * @return time in nanoseconds from now until the next attempt.
 */
    long nextMaxInterval() {
      long interval = (long) (period * Math.pow(1.5, attempt - 1));
      return interval > maxPeriod ? maxPeriod : interval;
    }
      
  }
}