前言：微服务架构，不可避免的存在单个微服务有多个实例，那么客户端如何将请求分摊到多个微服务的实例上呢？这里我们就需要使用负载均衡了

　　Ribbon是Netflix发布的负载均衡器，它有助于控制HTTP和TCP客户端的行为。为Ribbon配置服务提供者地址列表后，Ribbon就可基于某种负载均衡算法，自动地帮助服务消费者去请求。Ribbon默认为我们提供了很多的负载均衡算法，例如：轮询，随机等，也可自定义；

Ribbon的GitHub：https://github.com/Netflix/ribbon

　　而在SpringCloud中使用Ribbon和Eureka时，Ribbon会自动从EurekaServer中获取服务提供者地址列表，并基于负载均衡算法。

​1、创建EurekaServer，EurekaClient1，EurekaClient2，之前已经说过了Eureka的使用，这里直接上代码：

EurekaServer：

  1. @SpringBootApplication
  2. @EnableEurekaServer
  3. public class ServerApplication {
  5.     public static void main(String[] args) {
  6.         SpringApplication.run(ServerApplication.class,args);
  7.     }
  9. }

ServerApplication.java 

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <project xmlns="http://maven.apache.org/POM/4.0.0"
  3.   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  4.   xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  5.   <modelVersion>4.0.0</modelVersion>
  6.  
  7.   <groupId>com.cn</groupId>
  8.   <artifactId>eureka-ribbon-server</artifactId>
  9.   <version>1.0-SNAPSHOT</version>
  10.  
  11.   <properties>
  12.     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  13.     <java.version>1.8</java.version>
  14.   </properties>
  15.  
  16.   <parent>
  17.     <groupId>org.springframework.boot</groupId>
  18.     <artifactId>spring-boot-starter-parent</artifactId>
  19.     <version>1.5.13.RELEASE</version>
  20.   </parent>
  21.  
  22.   <dependencies>
  23.     <dependency>
  24.       <groupId>org.springframework.</groupId>
  25.       <artifactId></artifactId>
  26.     </dependency>
  27.     <dependency>
  28.       <groupId>org.springframework.cloud</groupId>
  29.       <artifactId>spring-cloud-starter-eureka-server</artifactId>
  30.     </dependency>
  31.   </dependencies>
  32.   <dependencyManagement>
  33.     <dependencies>
  34.       <dependency>
  35.         <groupId>org.springframework.cloud</groupId>
  36.         <artifactId>spring-cloud-dependencies</artifactId>
  37.         <version>Edgware.SR3</version>
  38.         <type>pom</type>
  39.         <scope>import</scope>
  40.       </dependency>
  41.     </dependencies>
  42.   </dependencyManagement>
  43.   <!-- 添加spring-boot的maven插件 -->
  44.   <build>
  45.     <plugins>
  46.       <plugin>
  47.         <groupId>org.springframework.boot</groupId>
  48.         <artifactId>spring-boot-maven-plugin</artifactId>
  49.       </plugin>
  50.     </plugins>
  51.   </build>
  52. </project>

pom.xml 

  1. server.port=8761
  2. #注意：这两个配置eureka默认为true，要改成false，否则会报错，connot connect server
  3. #表示是否将自己注册在EurekaServer上
  4. eureka.client.register-with-eureka=false
  5. #表示是否从EurekaServer获取注册信息
  6. eureka.client.fetch-registry=false
  8. eureka.client.service-url.defaultZone=http://localhost:8761/eureka/

application.properties

EurekaClient1:

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <project xmlns="http://maven.apache.org/POM/4.0.0"
  3.   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  4.   xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  5.   <modelVersion>4.0.0</modelVersion>
  6.  
  7.   <groupId>com.cn</groupId>
  8.   <artifactId>eureka-ribbon-client</artifactId>
  9.   <version>1.0-SNAPSHOT</version>
  10.  
  11.   <properties>
  12.     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  13.     <java.version>1.8</java.version>
  14.   </properties>
  15.  
  16.   <parent>
  17.     <groupId>org.springframework.boot</groupId>
  18.     <artifactId>spring-boot-starter-parent</artifactId>
  19.     <version>1.5.13.RELEASE</version>
  20.   </parent>
  21.  
  22.   <dependencies>
  23.     <dependency>
  24.       <groupId>org.springframework.cloud</groupId>
  25.       <artifactId>spring-cloud-starter-ribbon</artifactId>
  26.     </dependency>
  27.     <dependency>
  28.       <groupId>org.springframework.cloud</groupId>
  29.       <artifactId>spring-cloud-starter-eureka</artifactId>
  30.     </dependency>
  31.   </dependencies>
  32.   <dependencyManagement>
  33.     <dependencies>
  34.       <dependency>
  35.         <groupId>org.springframework.cloud</groupId>
  36.         <artifactId>spring-cloud-dependencies</artifactId>
  37.         <version>Edgware.SR3</version>
  38.         <type>pom</type>
  39.         <scope>import</scope>
  40.       </dependency>
  41.     </dependencies>
  42.   </dependencyManagement>
  43.   <!-- 添加spring-boot的maven插件 -->
  44.   <build>
  45.     <plugins>
  46.       <plugin>
  47.         <groupId>org.springframework.boot</groupId>
  48.         <artifactId>spring-boot-maven-plugin</artifactId>
  49.       </plugin>
  50.     </plugins>
  51.   </build>
  52. </project>

pom.xml 

  1. server.port=8762
  2. spring.application.name=client-8762
  3. eureka.client.service-url.defaultZone=http://localhost:8761/eureka/

application.properties

而在启动类中加入RestTemplate远程调用实例到容器中，并且添加LoadBalanced注解，使RestTemplate具备负载均衡的能力：

  1. @SpringBootApplication
  2. @EnableDiscoveryClient
  3. public class ClientApplication {
  5.     public static void main(String[] args) {
  6.         SpringApplication.run(ClientApplication.class, args);
  7.     }
  9.     /** 
  10.      * @Description: 加入@LoadBalanced注解，就可以为RestTemplate加入负载均衡的能力 
  11.      * @Param:
  12.      * @return:  
  13.      * @Author:  
  14.      * @Date: 2018/6/15 
  15.      */ 
  16.     @Bean
  17.     @LoadBalanced
  18.     public RestTemplate getRestTemplate() {
  19.         return new RestTemplate();
  20.     }
  22. }

创建Controller，注入RestTemplate、LoadBalancerClient实例：

  1. package com.cn.controller;
  3. import org.springframework.beans.factory.annotation.Autowired;
  4. import org.springframework.cloud.client.ServiceInstance;
  5. import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
  6. import org.springframework.stereotype.Controller;
  7. import org.springframework.web.bind.annotation.GetMapping;
  8. import org.springframework.web.bind.annotation.ResponseBody;
  9. import org.springframework.web.client.RestTemplate;
  11. /**
  12.  * @program: springcloud-example
  13.  * @description:
  14.  * @author: 
  15.  * @create: 2018-06-15 15:55
  16.  **/
  17. @Controller
  18. public class RibbonController {
  20.     @Autowired
  21.     private LoadBalancerClient loadBalancerClient;
  23.     @Autowired
  24.     private RestTemplate restTemplate;
  26.     @GetMapping("/loadInstance")
  27.     @ResponseBody
  28.     public String loadInstance() {
  29.         ServiceInstance choose = this.loadBalancerClient.choose("client-87");
  30.         System.out.println(choose.getServiceId()+":"+choose.getHost()+":"+choose.getPort());
  31.         return choose.getServiceId() + ":" + choose.getHost() + ":" + choose.getPort();
  32.     }
  34. }

EurekaClient2：

pom.xml与EurekaClient1中一致

application.xml:

  1. server.port=8763
  2. spring.application.name=client-87
  3. eureka.client.service-url.defaultZone=http://localhost:8761/eureka

  1. package com.cn;
  3. import org.springframework.boot.SpringApplication;
  4. import org.springframework.boot.autoconfigure.SpringBootApplication;
  5. import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
  7. /**
  8.  * @program: springcloud-example
  9.  * @description:
  10.  * @author: 535504
  11.  * @create: 2018-06-15 16:05
  12.  **/
  13. @SpringBootApplication
  14. @EnableDiscoveryClient
  15. public class ClientApplication {
  17.     public static void main(String[] args) {
  18.         SpringApplication.run(ClientApplication.class, args);
  19.     }
  21. }

ClientApplication

ClientController.java:

  1. package com.cn.contorller;
  3. import org.springframework.stereotype.Controller;
  4. import org.springframework.web.bind.annotation.GetMapping;
  5. import org.springframework.web.bind.annotation.ResponseBody;
  7. /**
  8.  * @program: springcloud-example
  9.  * @description:
  10.  * @author: 
  11.  * @create: 2018-06-15 16:12
  12.  **/
  13. @Controller
  14. public class ClientController {
  16.     @GetMapping("/getUser")
  17.     @ResponseBody
  18.     public String getUser() {
  19.         System.out.println("获取用户成功");
  20.         return "获取用户成功";
  21.     }
  23. }

2、启动顺序：

　　①、依次启动EurekaServer =》 EurekaClient1 =》 EurekaClient2   ；

　　②、然后将EurekaClient2中的application.properties的server.port=8763改为server.port=8764，再次启动该项目;

　　③、打开EurekaServer的配置页面（http://localhost:8761/），如下：

　　④、我们在地址栏输入http://localhost:8762/loadInstance，多刷新几次，会发现每次调用的端口实例都不同，如下图：

　　　　

　　　　

　　⑤、我们在看控制台，如图：

　　　　

 

至此，Ribbon已经入门，是不是很简单，但是这只是最简单的应用，九牛一毛尔…学无止境乎！

 

 

 示例代码：https://gitee.com/lfalex/springcloud-example

posted on 2018-06-15 17:12 lfalex 阅读(…) 评论(…) 编辑 收藏

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