通用方式整合Hystrix

一新建项目microservice-consumer-movie-ribbon-hystrix

二为项目添加以下依赖

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

三在启动类上添加注解@EnableCircuitBreaker或@Enablehystrix,从而为项目添加断路器功能

package com.itmuch.cloud.study;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@EnableDiscoveryClient
@SpringBootApplication
@EnableCircuitBreaker
public class ConsumerMovieApplication {
  @Bean
  @LoadBalanced
  public RestTemplate restTemplate() {
    return new RestTemplate();
  }

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

四修改MovieController，让其中的findByid方法具有容错能力

package com.itmuch.cloud.study.user.controller;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import com.itmuch.cloud.study.user.entity.User;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;

@RestController
public class MovieController {
  private static final Logger LOGGER = LoggerFactory.getLogger(MovieController.class);
  @Autowired
  private RestTemplate restTemplate;
  @Autowired
  private LoadBalancerClient loadBalancerClient;

  @HystrixCommand(fallbackMethod = "findByIdFallback")
  @GetMapping("/user/{id}")
  public User findById(@PathVariable Long id) {
    return this.restTemplate.getForObject("http://microservice-provider-user/" + id, User.class);
  }

  public User findByIdFallback(Long id) {
    User user = new User();
    user.setId(-1L);
    user.setName("默认用户");
    return user;
  }

  @GetMapping("/log-user-instance")
  public void logUserInstance() {
    ServiceInstance serviceInstance = this.loadBalancerClient.choose("microservice-provider-user");
    // 打印当前选择的是哪个节点
    MovieController.LOGGER.info("{}:{}:{}", serviceInstance.getServiceId(), serviceInstance.getHost(), serviceInstance.getPort());
  }
}

五测试

1 启动eureka

2 启动user微服务

3 启动movie微服务

4 访问http://localhost:8010/user/1，结果如下

{"id":1,"username":"account1","name":"张三","age":20,"balance":100.00}

5 停止user微服务

6 再次访问http://localhost:8010/user/1，结果如下

{"id":-1,"username":null,"name":"默认用户","age":null,"balance":null}

说明当前微服务不可用，进入回退方法。

通用方式整合Hystrix

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