熔断器

曾经终败给现在 2021-12-22 12:49 301阅读 0赞

# 一、引入依赖 #

## 1.consumer\_service中加入依赖 ##

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

## 2.开启熔断的注解 ##

//注解简化写法：微服务中，注解往往引入多个，简化注解可以使用组合注解。@SpringCloudApplication =等同于@SpringBootApplication+@EnableDiscoveryClient+@EnableCircuitBreaker
    @SpringBootApplication
    @EnableDiscoveryClient//开启服务发现
    @EnableCircuitBreaker//开启熔断
    public class ConsumerApplication {
        @Bean
        @LoadBalanced//开启负载均衡
        public RestTemplate restTemplate(){
            return new RestTemplate();
        }
        public static void main(String[] args) {
            SpringApplication.run(ConsumerApplication.class,args);
        }
    }

## 3.编写服务降级处理方法：使用@HystrixCommand定义fallback方法。 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzM5MTc5OTkz_size_16_color_FFFFFF_t_70]

package com.william.controller;
    
    import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.cloud.client.ServiceInstance;
    import org.springframework.cloud.client.discovery.DiscoveryClient;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    import org.springframework.web.client.RestTemplate;
    
    import javax.annotation.Resource;
    import java.util.List;
    
    /**
     * @author ：lijunxuan
     * @date ：Created in 2019/6/29  9:54
     * @description ：
     * @version: 1.0
     */
    @RestController
    @RequestMapping("/consumer")
    public class ConsumerController {
         @Resource
        RestTemplate restTemplate;
         @Resource
         DiscoveryClient discoveryClient;  //发现客户端对象
         @RequestMapping("/findUser")
         @HystrixCommand(fallbackMethod ="findUserFallback")
        public String findUser(Integer id){
             //请求服务提供者的查询用户详情地址
             // String url="http://localhost:9091/user/findById?id="+id;alt+enter  找到format
             String url= String.format("http://user-service/user/findById?id=%d", id);
    //        String url= String.format("http://localhost:9091/user/findById?id=%d", id);
    //        /*
    //        * 动态获取服务注册中心的，服务提供者地址*/
    //         /**
    //          * 操作快捷键
    //          *   找到privider_service-> application.yml->   user-service   先复制  然后按住crtl +e  回到这个位置
    //          *   discoveryClient.getInstances("user-service")     ctrl +alt +v  和.var的效果相同
    //          *    List<ServiceInstance> instances = discoveryClient.getInstances("user-service");
    //          */
    //         //获取注册中心的所有user-service用户注册实例
    //         List<ServiceInstance> instances = discoveryClient.getInstances("user-service");
    //         //获取第一个实例
    //         ServiceInstance serviceInstance = instances.get(0);
    //         int port = serviceInstance.getPort();
    //         String host = serviceInstance.getHost();
    //         url= String.format("http://%s:%d/user/findById?id=%d", host, port, id);
             return restTemplate.getForObject(url,String.class);
         }
         public String findUserFallback(Integer id){
             return "对不起，网络太拥挤了！";
         }
    
    }

## 测试结果 ##

需要把这两个服务给关闭  
![在这里插入图片描述][20190629175051403.png]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzM5MTc5OTkz_size_16_color_FFFFFF_t_70 1]

## 全局的配置 ##

在 ConsumerController配置  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzM5MTc5OTkz_size_16_color_FFFFFF_t_70 2]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzM5MTc5OTkz_size_16_color_FFFFFF_t_70 3]

@DefaultProperties(defaultFallback = "defaultFallback")
      public String defaultFallback(){
            return "全局默认：对不起，网络太拥挤了！";
        }

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzM5MTc5OTkz_size_16_color_FFFFFF_t_70]: /images/20211220/b6248d1921db4b2a805a260f7099757c.png
[20190629175051403.png]: /images/20211220/200aabc3298f46a593a07dfb9fd69dd0.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzM5MTc5OTkz_size_16_color_FFFFFF_t_70 1]: /images/20211220/7d7169a7b2cd4d00b621beb0a478b140.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzM5MTc5OTkz_size_16_color_FFFFFF_t_70 2]: /images/20211220/ee51daec02c243b394aad58e382bfcac.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzM5MTc5OTkz_size_16_color_FFFFFF_t_70 3]: /images/20211220/fc14ef90191b4499ac94aa9e4be4c88d.png