springCloud學習筆記系列(3)-服務容錯保護：Spring Cloud Feign

Feign包含了Ribbon和Hystrix，這個在實戰中才慢慢體會到它的意義，所謂的包含並非Feign的jar包包含有Ribbon和Hystrix的jar包這種物理上的包含，而是Feign的功能包含了其餘二者的功能這種邏輯上的包含。簡言之：Feign能幹Ribbon和Hystrix的事情，可是要用Ribbon和Hystrix自帶的註解必需要引入相應的jar包才能夠。

1.引入依賴

<!-- https://mvnrepository.com/artifact/org.springframework.cloud/spring-cloud-starter-feign -->

<dependency>

<groupId>org.springframework.cloud</groupId>

<artifactId>spring-cloud-starter-feign</artifactId>

<version>1.4.6.RELEASE</version>

</dependency>

2.配置文件中開啓服務

feign.hystrix.enabled=true

3.啓動類註解開啓

@EnableFeignClients

public class DemoFeignApplication {

public static void main(String[] args) {

SpringApplication.run(DemoFeignApplication.class, args);

}

}

4.feign 是基於接口的註解方式實現的新建一個接口

@FeignClient(value = "two-client",fallback = SchedualServiceHiHystric.class)

public interface UserService {

@RequestMapping("/home/indexd")

String getIndex();

}

FeignClient("two-client"")註解裏eureka-client指的是提供服務的服務名

fallback 自定義異常類

5.異常類的實現

@Component

public class SchedualServiceHiHystric implements UserService {

@Override

public String getIndex() {

return "服務沒有開啓";

}

}

 6.請求controller

@Autowired

private UserService userService;

 

@RequestMapping("/index")

public String index(){

logger.info("index方法");

return userService.getIndex();

}

7.結果,當調用的服務端沒有開啓的時候

註釋:1.maven的依賴必定要匹配,否則版本不匹配就會報不少沒法預知的異常(本人遇到很坑)

2.配置貼出來供參考

<dependencies>

<!--EuekaClient客戶端依賴-->

<dependency>

<groupId>org.springframework.cloud</groupId>

<artifactId>spring-cloud-starter-eureka</artifactId>

<version>1.3.6.RELEASE</version>

</dependency>

<!--Web端依賴-->

<dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-web</artifactId>

</dependency>

<dependency>

<groupId>org.springframework.cloud</groupId>

<artifactId>spring-cloud-starter-feign</artifactId>

<version>1.3.6.RELEASE</version>

</dependency>

</dependencies>

#server.port=8013
#eureka.client.service-url.defaultZone=http://localhost:8000/eureka/
#spring.application.name=three-client
#feign.hystrix.enabled=true
server:
  port: 8013
eureka:
  client:
    service-url:
      defaultZone: http://localhost:8000/eureka/
spring:
  application:
    name: three-client
feign:
  hystrix:
    enabled: true

hystrix:
  threadpool:
    default:
      coreSize: 500 #缺省爲10
  stream:
    maxConcurrentConnections: 20
    bus:
      enabled: true
  command:
    default:
      execution:
        timeout:
          enabled: false
        isolation:
          thread:
            timeoutInMilliseconds: 60000
ribbon:
  eureka:
    enabled: true