SpringCloud-客户端的负载均衡Ribbon(三)

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

一、Ribbon简介

  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。

二、Ribbon实战

​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:

@SpringBootApplication
@EnableEurekaServer
public class ServerApplication {

    public static void main(String[] args) {
        SpringApplication.run(ServerApplication.class,args);
    }

}
ServerApplication.java
<?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>

  <groupId>com.cn</groupId>
  <artifactId>eureka-ribbon-server</artifactId>
  <version>1.0-SNAPSHOT</version>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <java.version>1.8</java.version>
  </properties>

  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.13.RELEASE</version>
  </parent>

  <dependencies>
    <dependency>
      <groupId>org.springframework.</groupId>
      <artifactId></artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-eureka-server</artifactId>
    </dependency>
  </dependencies>
  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-dependencies</artifactId>
        <version>Edgware.SR3</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>
  </dependencyManagement>
  <!-- 添加spring-boot的maven插件 -->
  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
    </plugins>
  </build>
</project>
pom.xml
server.port=8761
#注意:这两个配置eureka默认为true,要改成false,否则会报错,connot connect server
#表示是否将自己注册在EurekaServer上
eureka.client.register-with-eureka=false
#表示是否从EurekaServer获取注册信息
eureka.client.fetch-registry=false

eureka.client.service-url.defaultZone=http://localhost:8761/eureka/
application.properties

EurekaClient1:

<?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>

  <groupId>com.cn</groupId>
  <artifactId>eureka-ribbon-client</artifactId>
  <version>1.0-SNAPSHOT</version>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <java.version>1.8</java.version>
  </properties>

  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.13.RELEASE</version>
  </parent>

  <dependencies>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-ribbon</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-eureka</artifactId>
    </dependency>
  </dependencies>
  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-dependencies</artifactId>
        <version>Edgware.SR3</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>
  </dependencyManagement>
  <!-- 添加spring-boot的maven插件 -->
  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
    </plugins>
  </build>
</project>
pom.xml
server.port=8762
spring.application.name=client-8762
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

@SpringBootApplication
@EnableDiscoveryClient
public class ClientApplication {

    public static void main(String[] args) {
        SpringApplication.run(ClientApplication.class, args);
    }

    /** 
     * @Description: 加入@LoadBalanced注解,就可以为RestTemplate加入负载均衡的能力 
     * @Param:
     * @return:  
     * @Author:  
     * @Date: 2018/6/15 
     */ 
    @Bean
    @LoadBalanced
    public RestTemplate getRestTemplate() {
        return new RestTemplate();
    }

}

创建Controller,注入RestTemplate、LoadBalancerClient实例:

package com.cn.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.client.RestTemplate;

/**
 * @program: springcloud-example
 * @description:
 * @author: 
 * @create: 2018-06-15 15:55
 **/
@Controller
public class RibbonController {

    @Autowired
    private LoadBalancerClient loadBalancerClient;

    @Autowired
    private RestTemplate restTemplate;

    @GetMapping("/loadInstance")
    @ResponseBody
    public String loadInstance() {
        ServiceInstance choose = this.loadBalancerClient.choose("client-87");
        System.out.println(choose.getServiceId()+":"+choose.getHost()+":"+choose.getPort());
        return choose.getServiceId() + ":" + choose.getHost() + ":" + choose.getPort();
    }

}

EurekaClient2:

pom.xml与EurekaClient1中一致

application.xml:

server.port=8763
spring.application.name=client-87
eureka.client.service-url.defaultZone=http://localhost:8761/eureka
package com.cn;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

/**
 * @program: springcloud-example
 * @description:
 * @author: 535504
 * @create: 2018-06-15 16:05
 **/
@SpringBootApplication
@EnableDiscoveryClient
public class ClientApplication {

    public static void main(String[] args) {
        SpringApplication.run(ClientApplication.class, args);
    }

}
ClientApplication

ClientController.java:

package com.cn.contorller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ResponseBody;

/**
 * @program: springcloud-example
 * @description:
 * @author: 
 * @create: 2018-06-15 16:12
 **/
@Controller
public class ClientController {

    @GetMapping("/getUser")
    @ResponseBody
    public String getUser() {
        System.out.println("获取用户成功");
        return "获取用户成功";
    }

}

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 @ 2018-06-15 17:12 lfalex 阅读(...) 评论(...) 编辑 收藏