springcloud系列(5) - 熔断

熔断是在服务端，抛出异常的时候，会调用fallback的方法，然后返回提示信息，不是太理解的是感觉这个跟异常处理很像，有什么不同吗？（抛出异常的时候，由handler捕获到，然后返回提示信息，感觉很像，就是不太清楚有什么区别，虽然一个是正常返回，一个是异常返回，不管了，以后要是遇到某种场景要是顿悟的话，再回来改）

首先在父工程中引入依赖

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-hystrix</artifactId>
            <version>1.3.2.RELEASE</version>
        </dependency>

然后copy一个用户模块，改名user-service-hystrix

启动类上加： @EnableHystrix

@SpringBootApplication
@EnableDiscoveryClient
@EnableHystrix
public class UserServiceApplication {

    public static void main(String[] args) {
        SpringApplication.run(UserServiceApplication.class,args);
    }
}

修改application.yml 的端口号和服务名称

spring:
  application:
    name: user-service-hystrix

server:
  port: 8804

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8888/eureka/

修改用户服务的controller:

@RequestMapping("/v1")
@Controller
public class UserController {

    @HystrixCommand(fallbackMethod = "fallback")
    @RequestMapping(value = "/user/{pk}")
    public ResponseEntity<?> getUserInfo(@PathVariable("pk") long pk){
        UserInfoResp userInfos= new UserInfoResp();
        userInfos.setNickName("cara liu1");
        userInfos.setPk(1L);
        userInfos.setPhoneNumber("18814098957");
        if(pk <= 0){
            throw new RuntimeException();
        }
        return new ResponseEntity<>(userInfos, HttpStatus.OK);
    }

    // 熔断后，调用的方法
    public ResponseEntity<?> fallback(@PathVariable("pk") long pk){
        UserInfoResp userInfos= new UserInfoResp();
        userInfos.setNickName("service error,please try again");
        return new ResponseEntity<>(userInfos,HttpStatus.OK);
    }
}

然后在订单服务中创建一个：RibbonUserServiceHystrix.java

@FeignClient(value = "USER-SERVICE-HYSTRIX")
public interface RibbonUserServiceHystrix {

    @RequestMapping(value = "/v1/user/{pk}",method = RequestMethod.GET)
    UserInfoResp getUserInfoFeign(@PathVariable("pk") long pk);
}

启动类上加上开启hystrix的注解

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
@EnableHystrix
public class OrderServiceApplication {

    public static void main(String[] args) {
        SpringApplication.run(OrderServiceApplication.class,args);
    }
}

添加一个调用的接口，修改后为：

@Controller
@RequestMapping("/v1")
public class OrderController {


    @Autowired
    private RibbonUserService ribbonUserService;
    @Autowired
    private RibbonUserServiceHystrix ribbonUserServiceHystrix;
    @RequestMapping(value = "/order/feign",method = RequestMethod.GET)
    public ResponseEntity<?> getOrder(){
        UserInfoResp userInfoResp = ribbonUserService.getUserInfoFeign();
        return new ResponseEntity<>(userInfoResp, HttpStatus.OK);
    }

    @RequestMapping(value = "/order/feign/{pk}",method = RequestMethod.GET)
    public ResponseEntity<?> getOrder(@PathVariable long pk){
        UserInfoResp userInfoResp = ribbonUserServiceHystrix.getUserInfoFeign(pk);
        return new ResponseEntity<>(userInfoResp, HttpStatus.OK);
    }
}

然后重新启动该订单服务和相应的用户服务，然后调用接口：

GET  http://localhost:8803/v1/order/feign/-1

返回结果：

{

"pk": 0,

"nickName": "service error,please try again",

"phoneNumber": null

}