【SpringCloud NetFlix】 SpringCloud整合Hystrix（三）整合Feign

SpringCloud整合Hystrix（三）整合Feign

Feign整合Hystrix

回退机制配置

引入依赖

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-hystrix</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-feign</artifactId>
        </dependency>

主启动类

@SpringBootApplication
@EnableEurekaClient
@EnableCircuitBreaker
@ServletComponentScan
//打开Feign的开关
@EnableFeignClients
public class SaleApp {

    @Bean
    @LoadBalanced
    public RestTemplate getRestTemplate() {
        return new RestTemplate();
    }

    public static void main(String[] args) {
        new SpringApplicationBuilder(SaleApp.class).web(true).run(args);
    }
}

在application.yml里面打开feign整合Hystrix的开关

feign:
  hystrix:
    enabled: true

断路器配置

application.yml

针对某个方法配置

hystrix:
  command:
    HelloClient#toHello():   #该方法超过0.5秒，断路器熔断触发回退的方法
      execution:
        isolation:
          thread: 
            timeoutInMilliseconds: 500
      circuitBreaker: #10秒内请求数量超过3次满足熔断第一个条件，如果请求中50%的请求是失败的满足第二个条件
        requestVolumeThreshold: 3

针对全局配置

hystrix:
  command:
    default:
      execution:
        isolation:
          thread: 
            timeoutInMilliseconds: 500
      circuitBreaker:
        requestVolumeThreshold: 3

服务方提供的接口

    @RequestMapping(value = "/hello", method = RequestMethod.GET)
    public String hello() {
        return "hello";
    }

    @RequestMapping(value = "/toHello", method = RequestMethod.GET)
    public String toHello() throws Exception {
        Thread.sleep(1000);
        return "timeout hello";
    }

调用方接口

@FeignClient(name = "spring-hy-member", fallback = HelloClientFallback.class)
public interface HelloClient {

    //Feign翻译器翻译了四个注解：
    //@RequestMapping;@RequestParm;@RequestHeader;@PathVariable
    @RequestMapping(method = RequestMethod.GET, value = "/hello")
    public String hello();

    @RequestMapping(method = RequestMethod.GET, value = "/toHello")
    public String toHello();
}

回退方法

@Component
public class HelloClientFallback implements HelloClient {

    public String hello() {
        return "fallback hello";
    }

    public String toHello() {
        return "fallback timeout hello";
    }

}

测试调用

@RestController
public class FeignController {

    @Autowired
    private HelloClient helloClient;

    @RequestMapping(method = RequestMethod.GET, value = "/hello")
    public String hello() {
        return helloClient.hello();
    }
    //测试断路器
    @RequestMapping(method = RequestMethod.GET, value = "/toHello")
    public String toHello() {
        String result = helloClient.toHello();
        HystrixCircuitBreaker breaker = HystrixCircuitBreaker.Factory
                .getInstance(HystrixCommandKey.Factory
                        .asKey("HelloClient#toHello()"));   
        System.out.println("断路器状态：" + breaker.isOpen());
        return result;
    }
}

注意：

断路器开启后，短路默认5s 开始尝试是否恢复

参考：https://blog.csdn.net/tongtong_use/article/details/78611225
以上为疯狂SpringCloud微服务架构实战学习笔记
感谢杨恩雄老师：https://my.oschina.net/JavaLaw