0042-Feign使用Hystrix

1. pom依賴

依賴同feign一樣，不用修改，feign中默認包含了hystrix，側面說明hystrix是一個默認的組件，應該被開啓

<dependencies>
    <dependency>
        <groupId>com.honor</groupId>
        <artifactId>interface</artifactId>
        <version>1.0-SNAPSHOT</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-openfeign</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-actuator</artifactId>
    </dependency>
</dependencies>

2. yml配置

啓用hystrix,設置feign.hystrix.enabled=true

server:
  port: 9002

eureka:
  client:
    serviceUrl:
      defaultZone: http://eureka-server-7001:7001/eureka/,http://eureka-server-7002:7002/eureka/,http://eureka-server-7003:7003/eureka/
#      defaultZone: http://eureka-server-8001:8001/eureka/
  instance:
    instance-id: eureka-provider-9002 # 服務名稱
    prefer-ip-address: true # 顯示ip地址

# 啓用斷路器
feign:
  hystrix:
    enabled: true

info: # 點擊註冊列表未服務出現的信息
  app.name: springcloud
  company.name: www.honor.com
  build.artifactId: @project.artifactId@
  build.version: @project.version@

spring:
  application:
    name: eureka-consumer-feign

3. 修改feign客戶端

feign的客戶端在interface公共模塊中

3.1 方式一：創建fallback類

這種方式相當於實現一個service接口類，會和服務提供者衝突，因爲服務提供者也會實現service接口，不建議使用

// fallback類
@Component
public class HelloServiceFallBack implements IHelloService {
    public String sayHello(String name) {
        return "hello " + name + ", current service is disable, place try it later.";
    }
}

// 客戶端配置
@FeignClient(value = "eureka-provider", fallback = HelloServiceFallBack.class)
public interface IHelloService {
    /**
     * 打招呼
     *
     * @param name bb俠
     * @return
     */
    @GetMapping("/hello/{name}")
    // @PathVariable必須包含名稱，不然無法啓動
    String sayHello(@PathVariable("name") String name);
}

3.2 方式二：創建fallback工廠類

// fallback工廠
@Component
public class HelloServiceFallBackFactory implements FallbackFactory<IHelloService> {
    public IHelloService create(Throwable throwable) {
        return new IHelloService() {
            public String sayHello(String name) {
                return "hello " + name + ", current service is disable, place try it later.";
            }
        };
    }
}
// 配置
@FeignClient(value = "eureka-provider", fallbackFactory = HelloServiceFallBackFactory.class)
public interface IHelloService {
    /**
     * 打招呼
     *
     * @param name bb俠
     * @return
     */
    @GetMapping("/hello/{name}")
    // @PathVariable必須包含名稱，不然無法啓動
    String sayHello(@PathVariable("name") String name);
}

4. 主啓動類

和feign一樣沒有變更

@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients
public class EurekaConsumerFeignHystrix9002Application {
    public static void main(String[] args) {
        SpringApplication.run(EurekaConsumerFeignHystrix9002Application.class, args);
    }
}

5. 測試

當服務提供者8001、8002、8003都正常時跟平時調用一樣沒有區別，關閉8003模擬服務故障，你會發現當輪詢到8003時，會返回fallbackMethod指定方法中的內容，當重試多次以後沒有用，服務調用者就不會訪問8003了，等一段時間後，又會嘗試訪問8003，如果還是不行就又熔斷，如果訪問成功了，那就恢復正常。