springcloud微服务hystrix熔断器之feign方式-08

╰+攻爆jí腚メ 2022-03-27 04:12 207阅读 0赞

[springcloud入门详细搭建微服务环境-01  注册中心搭建][springcloud_-01_]

[springcloud服务提供端-02][springcloud_-02]  服务提供端的搭建

此demo依赖于以上：

Hystrix “豪猪”，具有自我保护的能力。hystrix 通过如下机制来解决雪崩效应问题。

资源隔离（限流）：包括线程池隔离和信号量隔离，限制调用分布式服务的资源使用，某一个调用的服务出现问题不会影响其他服务调用。

融断：当失败率达到阀值自动触发降级(如因网络故障/超时造成的失败率高)，熔断器触发的快速失败会进行快速恢复。

降级机制：超时降级、资源不足时(线程或信号量)降级，降级后可以配合降级接口返回托底数据。

缓存：提供了请求缓存、请求合并实现。

feign方式：不用导入hystrix包，因为feign自带hystrix熔断器

### 1.导入服务消费端的依赖包 ###

<dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-openfeign</artifactId>
            </dependency>
    
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-config</artifactId>
            </dependency>

### 2.配置服务消费端 ###

server:
      port: 9003
    eureka:
      client:
        service-url:
         defaultZone: http://localhost:7001/eureka #告诉服务提供者要把服务注册到哪里
      instance:
        prefer-ip-address: true #显示客户端ip
    spring:
      application:
        name: USER-CONSUMER #不要使用下划线
    feign:
       hystrix:
           enabled: true #开启熔断支持
       client:
        config:
          remote-service:           #服务名，填写default为所有服务
            connectTimeout: 3000
            readTimeout: 3000
    hystrix:
      command:
          default:
            execution:
              isolation:
                thread:
                  timeoutInMilliseconds: 3000

###  3.写一个类去实现FallbackFactory，自定义托底 ###

package cn.mesmile.client;
    
    import cn.mesmile.domain.User;
    import feign.hystrix.FallbackFactory;
    import org.springframework.stereotype.Component;
    
    /**
     * @Created with IDEA
     * @author: Super Zheng
     * @Description: java类作用描述
     * @Date:2019/1/7
     * @Time:11:19
     *
     *  UserClient表示对哪个接口进行托底，一旦发生异常，就会调用此方法
     */
    @Component
    public class UserClientHystrixFallbackFactory implements FallbackFactory<UserClient> {
        @Override
        public UserClient create(Throwable throwable) {
            return new UserClient() {
                @Override
                public User getUser(Long id) {
                    return new User(id,"网络异常，feign");
                }
            };
        }
    }

### 4.写一个接口UserClient去调用服务，feign是面向接口的 ###

package cn.mesmile.client;
    
    import cn.mesmile.domain.User;
    import org.springframework.cloud.openfeign.FeignClient;
    import org.springframework.web.bind.annotation.PathVariable;
    import org.springframework.web.bind.annotation.RequestMapping;
    
    /**
     * @Created with IDEA
     * @author: Super Zheng
     * @Description: java类作用描述
     * @Date:2019/1/7
     * @Time:9:55
     *
     *  UserClientHystrixFallbackFactory为我们自定的托底函数
     */
    @FeignClient(value = "USER-PROVIDER",fallbackFactory = UserClientHystrixFallbackFactory.class)
    @RequestMapping("/provider")
    public interface UserClient {
        /**
         * 根据id获得user信息的方法
         * @param id
         * @return
         */
        @RequestMapping("/user/{id}")
        User getUser(@PathVariable(name = "id") Long id);
    }

### 5.写一个服务消费端的controller类 ###

package cn.mesmile.controller;
    
    import cn.mesmile.client.UserClient;
    import cn.mesmile.domain.User;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.PathVariable;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    /**
     * @Created with IDEA
     * @author: Super Zheng
     * @Description: java类作用描述
     * @Date:2019/1/7
     * @Time:11:11
     */
    @RestController
    @RequestMapping("/consumer")
    public class UserController {
    
        @Autowired
        private UserClient userClient;
    
        /**
         * feign方式通过调用接口的方法来从注册中心获取服务端数据
         * @param id
         * @return
         */
        @RequestMapping("/user/{id}")
        public User getUser(@PathVariable(name = "id") Long id){
            return userClient.getUser(id);
        }
    }

### 6.写一个服务消费端的入口类 ###

package cn.mesmile;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
    import org.springframework.cloud.openfeign.EnableFeignClients;
    
    /**
     * @Created with IDEA
     * @author: Super Zheng
     * @Description: java类作用描述
     * @Date:2019/1/7
     * @Time:11:09
     *
     *  这是扫描包，因为需要用到接口 UserClient  这个接口类不在当前包中
     *  @EnableFeignClients(basePackages = "cn.mesmile")
     */
    @SpringBootApplication
    @EnableEurekaClient
    @EnableFeignClients(basePackages = "cn.mesmile")
    public class ConsumerApplication9003 {
        public static void main(String[] args) {
            SpringApplication.run(ConsumerApplication9003.class);
        }
    }

### 7.启动注册中心入口类，启动服务提供端入口类，启动服务消费端的入口类 ###

查看结果：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N1cHJlemhlbmc_size_16_color_FFFFFF_t_70][]

我们将服务提供端关闭，查看异常时的结果：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N1cHJlemhlbmc_size_16_color_FFFFFF_t_70 1][]

[springcloud_-01_]: https://blog.csdn.net/suprezheng/article/details/86107570
[springcloud_-02]: https://blog.csdn.net/suprezheng/article/details/86180847
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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N1cHJlemhlbmc_size_16_color_FFFFFF_t_70 1]: /images/20220327/c2b40afdc6404ad6bf13803352796572.png