Hystrix断路器

1.消费者添加依赖

        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-netflix-hystrixartifactId>
        dependency>

2.消费者Application上添加注解，驱动Hystrix

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

3.在服务提供者添加接口

模拟服务提供者出现错误

 
@RestController
public class HystrixController {
    private static Long MaxSleepTime = 5000L;
 
    // 超时
    @RequestMapping("/timeout")
    public ResultMessage TestError() {
        try {
            Thread.sleep((long) (MaxSleepTime * Math.random()));
        } catch (InterruptedException e) {
            System.out.println("服务端在延时发生了异常");
            e.printStackTrace();
        }
        return new ResultMessage(true, "延时时间较短，没有触发超时异常，延时时间：" + MaxSleepTime);
    }
 
    //模拟发生了异常
    @GetMapping("/exp/{msg}")
    public ResultMessage exp(@PathVariable("msg") String msg) {
        if (msg.equals("hello")) {
            return new ResultMessage(true, msg);
        } else {
            throw new RuntimeException();
        }
    }
}

4.消费者增加 远程调用服务

@Service
public class UserService implements UserFacae {
    @Autowired
    RestTemplate restTemplate;
 
    @HystrixCommand(fallbackMethod = "fallbackTimeOut")
    @Override
    public ResultMessage timeout() {
        return restTemplate.getForObject("http://USER/timeout", ResultMessage.class);
    }
 
    @HystrixCommand(fallbackMethod = "fallbackError")
    @Override
    public ResultMessage accureError(String msg) {
        return restTemplate.getForObject("http://USER/exp/"+msg, ResultMessage.class);
    }
 
    public ResultMessage fallbackTimeOut() {
        return new ResultMessage(false, "该接口延时时间过长，引发了超时异常，启动消费者的异常处理方法");
    }
 
      public ResultMessage fallbackError(String msg) {
        return new ResultMessage(false, "发生异常,msg参数是："+msg);
    }
}

和controller和service

因为是通过resttemple远程调用的服务器的接口，所以这里不写interface，写 Facae

public interface UserFacae {
    public ResultMessage timeout();
 
    public ResultMessage accureError(String msg);
}

@RestController
public class UserController {
    @Autowired
    UserFacae userFacae;
 
    @RequestMapping("timeout")
    public ResultMessage timeout() {
        return userFacae.timeout();
    }
 
    @RequestMapping("/error/{msg}")
    public ResultMessage takeError(@PathVariable String msg) {
        return userFacae.accureError(msg);
    }
}

访问 localhost:7301/timeout

会有触发延时，因为时长随机的，所以会随机超时，引发超时异常，由消费端的fallbackTimeOut()方法捕获。

访问localhost:7301/error/hello123

如果参数是hello 不引发异常

如果参数是hello123 会引发异常，由消费端的fallbackError(String msg)方法捕获，注意，因为引发fallbackError(String msg)的accureError(String msg) 方法，有一个string类型的参数，所以异常处理参数也一定要有string类型的参数。