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ribbon是什么？

ribbon可以帮助我们实现负载均衡的效果。只需使用@LoadBalanced注解即可实现。使用方便快捷。

直接上手：

这次我们使用上一博文的工程，启动服务注册 工程，以及启动两个服务并注册到注册中心。

新建一个ribbon工程：

pom文件如下：

<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.1.5.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.springcloud</groupId> <artifactId>wujie_study_day02_eureka_ribbon</artifactId> <version>0.0.1-SNAPSHOT</version> <name>wujie_study_day02_eureka_ribbon</name> <description>Demo project for Spring Boot</description> <properties> <java.version>1.8</java.version> <spring-cloud.version>Greenwich.SR1</spring-cloud.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</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-netflix-ribbon</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <dependencyManagement> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-dependencies</artifactId> <version>${spring-cloud.version}</version> <type>pom</type> <scope>import</scope> </dependency> </dependencies> </dependencyManagement> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>

修改配置文件如下：

server: port: 8891 spring: application: name: eureka_ribbon eureka: client: service-url: defaultZone: http://localhost:8888/eureka

在启动类上加注解@EnableDiscoveryClient向服务中心注册，并且注入一个restTemplate的bean。通过@LoadBalanced注解开启负载均衡。

package com.springcloud.wujie_study_day02_eureka_ribbon; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; 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; @SpringBootApplication @EnableDiscoveryClient public class WujieStudyDay02EurekaRibbonApplication { public static void main(String[] args) { SpringApplication.run(WujieStudyDay02EurekaRibbonApplication.class, args); } @Bean @LoadBalanced public RestTemplate restTemplate(){ return new RestTemplate(); } }

service层代码如下：

package com.springcloud.wujie_study_day02_eureka_ribbon.service; /** * @Classname ServerService * @Description TODO * @Date 2019/5/23 17:08 * @Created by wujie */ public interface ServerService { public String getInfo(String name); }

实现service层：

package com.springcloud.wujie_study_day02_eureka_ribbon.service.impl; import com.springcloud.wujie_study_day02_eureka_ribbon.service.ServerService; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import org.springframework.web.client.RestTemplate; /** * @Classname ServerServiceImpl * @Description TODO * @Date 2019/5/23 17:09 * @Created by wujie */ @Service public class ServerServiceImpl implements ServerService { @Autowired private RestTemplate restTemplate; @Override public String getInfo(String name) { return restTemplate.getForObject("http://wujie-study-day01-eureka-client/test?name="+name,String.class); } }

controller层实现如下：

package com.springcloud.wujie_study_day02_eureka_ribbon.controller; import com.springcloud.wujie_study_day02_eureka_ribbon.service.ServerService; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestParam; import org.springframework.web.bind.annotation.RestController; /** * @Classname RibbonController * @Description TODO * @Date 2019/5/23 17:05 * @Created by wujie */ @RestController public class RibbonController { @Autowired private ServerService serverService; @RequestMapping(value = "testRibbon") public String testRibbon(@RequestParam String name){ return serverService.getInfo(name); } }

最后启动这个项目并访问localhost:8891/testRibbon?name=XXX并多次请求出现如下图所示：

我们可以发现端口不一致，证明我们实现成功。