springcloud demo---ribbon

我就是我 2022-01-05 10:25 301阅读 0赞

# 1.概念 #

Spring Cloud Ribbon 是一个基于 Http 和 TCP 的客服端负载均衡工具，它是基于 Netflix Ribbon 实现的。客户端负载均衡即是当浏览器向后台发出请求的时候，客户端会向 Eureka Server读取注册到服务器的可用服务信息列表，然后根据设定的负载均衡策略（没有设置即用默认的，轮询 RoundRobinRule、随机 RandomRule策略），抉择出向哪台服务器发送请求。

# 2.ribbon案例 #

### 　　2.1 ribbon-client(和eureka-client类似) ###

server:
      port: 8764
    spring:
      application:
        name: ribbon-provider
    eureka:
      instance:
        lease-renewal-interval-in-seconds: 5
        lease-expiration-duration-in-seconds: 15
      client:
        healthcheck:
          enabled: true
        service-url:
          defaultZone: http://admin:123@localhost:8761/eureka/
    management:
      endpoints:
        web:
          exposure:
            include: '*'
      endpoint:
        health:
          show-details: ALWAYS

### 　　2.2 依赖 ###

<dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
                <version>2.0.0.RELEASE</version>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
                <version>2.0.0.RELEASE</version>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-hystrix-dashboard</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>
                <scope>test</scope>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-actuator</artifactId>
            </dependency>
    
            
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>springloaded</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-devtools</artifactId>
            </dependency>
        </dependencies>

### 　　3.启动类 ###

package com.transsion;
    
    import com.netflix.hystrix.contrib.metrics.eventstream.HystrixMetricsStreamServlet;
    import com.netflix.loadbalancer.IRule;
    import com.netflix.loadbalancer.RandomRule;
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.boot.web.servlet.ServletRegistrationBean;
    import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
    import org.springframework.cloud.client.loadbalancer.LoadBalanced;
    import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
    import org.springframework.cloud.netflix.hystrix.EnableHystrix;
    import org.springframework.cloud.netflix.hystrix.dashboard.EnableHystrixDashboard;
    import org.springframework.context.annotation.Bean;
    import org.springframework.web.client.RestTemplate;
    
    @SpringBootApplication
    @EnableEurekaClient
    @EnableCircuitBreaker//熔断的注解
    public class RibbonProviderApplication {
    
        //同时通过 @LoadBalanced 开启 restTemplate 负载均衡功能。
        @Bean
        @LoadBalanced
        public RestTemplate restTemplate(){
            return new RestTemplate();
        }
    
        public static void main(String[] args) {
            SpringApplication.run(RibbonProviderApplication.class, args);
        }
    
        /*@Bean
        public ServletRegistrationBean getServlet() {
            HystrixMetricsStreamServlet streamServlet = new HystrixMetricsStreamServlet();
            ServletRegistrationBean registrationBean = new ServletRegistrationBean(streamServlet);
            registrationBean.setLoadOnStartup(1);
            registrationBean.addUrlMappings("/hystrix.stream");
            registrationBean.setName("HystrixMetricsStreamServlet");
            return registrationBean;
        }*/
    }

### 　　4.CallService和CallController　　 ###

创建 Service，通过 restTemplate 消费 Client 服务的接口return restTemplate.getForObject("http://PROVIDER/test", String.class);  
　　　　其中：PROVIDER为已经注册的client的applicationName，test为该client的接口

package com.transsion;
    
    
    import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
    import com.netflix.ribbon.proxy.annotation.Hystrix;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.cloud.netflix.hystrix.EnableHystrix;
    import org.springframework.stereotype.Service;
    import org.springframework.web.client.RestTemplate;
    
    @Service
    public class CallService {
    
        @Autowired
        private RestTemplate restTemplate;
    
    
        @HystrixCommand(fallbackMethod = "helloFallback")
        public String port(){
            return restTemplate.getForObject("http://PROVIDER/test", String.class);
        }
    　　
    　　/*熔断相关，后续会进行讲解*/
        public String helloFallback() {
            return "error";
        }
    
    }

package com.transsion;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    
    @RestController
    //@RequestMapping("/call")
    public class CallController {
    
        @Autowired
        CallService callService;
    
        @RequestMapping("test")
        public String port() {
            return callService.port();
        }
    }

### 　　5.访问地址 ###

首先开启eureke-server,接着启动两个client,访问地址http://localhost:8764/test,页面内容会在根据两个client中的test方法切换。当其中一个client停止是，会发生熔断，显示error。而另一个client则显示正常的内容。

转载于:https://www.cnblogs.com/rainsakura/p/10407349.html