客户端负载均衡器

在SpringCloud中Ribbon负载均衡客户端，会从eureka注册中心服务器端上获取服务注册信息列表，缓存到本地。

让后在本地实现轮训负载均衡策略。

Ribbon与Nginx区别

1.服务器端负载均衡Nginx

nginx是客户端所有请求统一交给nginx，由nginx进行实现负载均衡请求转发，属于服务器端负载均衡。

既请求有nginx服务器端进行转发。

2.客户端负载均衡Ribbon

Ribbon是从eureka注册中心服务器端上获取服务注册信息列表，缓存到本地，让后在本地实现轮训负载均衡策略。

既在客户端实现负载均衡。

应用场景的区别：

Nginx适合于服务器端实现负载均衡 比如Tomcat ，Ribbon适合与在微服务中RPC远程调用实现本地服务负载均衡，比如Dubbo、SpringCloud中都是采用本地负载均衡。

Ribbon是Spring Cloud （本地）客户端负载均衡器

Ribbon底层实现：

Member：

img

pom：

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<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.toov5</groupId>
  <artifactId>member</artifactId>
  <version>0.0.1-SNAPSHOT</version>
   
   
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.1.RELEASE</version>
    </parent>
    <!-- 管理依赖 -->
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Finchley.M7</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <dependencies>
        <!-- SpringBoot整合Web组件 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!-- SpringBoot整合eureka客户端 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
    </dependencies>
    <!-- 注意： 这里必须要添加， 否者各种依赖有问题 -->
    <repositories>
        <repository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/libs-milestone</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </repository>
    </repositories>
   
</project>

　　yml：

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###服务启动端口号
server:
  port: 8009
###服务名称(服务注册到eureka名称) 
spring:
    application:
        name: app-toov5-member
###服务注册到eureka地址
eureka:
  client:
    service-url:
    ##当前会员注册到eureka服务  地址+端口号
           defaultZone: http://127.0.0.1:8100/eureka
            
###因为该应用为注册中心，不会注册自己
    register-with-eureka: true
###是否需要从eureka上获取注册信息
    fetch-registry: true

Controller类

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package com.toov5.api.controller;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class MemberApiController {
    @Value("${server.port}")
    private String serverPort;
    
    @RequestMapping("/getMember")
  public String getMember() {
        return "会员服务"+serverPort;
  }
}

　　

启动类：

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package com.toov5.api;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

@SpringBootApplication
@EnableEurekaClient   //注册到eureka
public class AppMember {
   
    public static void main(String[] args) {
        SpringApplication.run(AppMember.class, args);
    }
    
}

Order

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Controlller

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package com.toov5.api.controller;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

//纯手写Ribbon本地负载均衡
@RestController
public class ExtRibbonController {
    @Autowired
    private DiscoveryClient discoveryClient;
    @Autowired
    private RestTemplate restTemplate;
    //定义请求数
    private int reqCount;
    
@RequestMapping("/ribbonMember")    
   public String ribbonMember() {
       //互殴去对应服务器远程调用地址
      String  instanceUrl =  getInstance()+"/getMember";
      System.out.println("instanceUrl"+instanceUrl);
        //直接使用httpclient远程调用。本次使用rest方式
      String result = restTemplate.getForObject(instanceUrl, String.class);  //底层使用httpclient实现的
       return result;
   }
   private String getInstance() {
       List<ServiceInstance> instances = discoveryClient.getInstances("app-toov5-member");
       if (instances==null || instances.size()==0) {
        return null;
    }
       int instanceSize = instances.size();
       int serviceIndex = reqCount%instanceSize;
       reqCount++;
        
       return instances.get(serviceIndex).getUri().toString();
   }
}

启动类：

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package com.toov5.api.controller;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableEurekaClient
public class AppOrder {
  public static void main(String[] args) {
    SpringApplication.run(AppOrder.class, args);
}
  //解决RestTemplate找不到问题  把restTemplate注册到Spring Boot容器中
  @Bean
//  @LoadBalanced   手写的 不要去实现本地负载均衡效果了
  RestTemplate restTemplate() {  
      return new RestTemplate();
  }
  
}

yml：

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###服务启动端口号
server:
  port: 8002
###服务名称(服务注册到eureka名称) 
spring:
    application:
        name: app-toov5-order
###服务注册到eureka地址
eureka:
  client:
    service-url:
           defaultZone: http://127.0.0.1:8100/eureka
 
            
###因为该应用为注册中心，不会注册自己
    register-with-eureka: true
###是否需要从eureka上获取注册信息
    fetch-registry: true

　　pom

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<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.toov5</groupId>
  <artifactId>order</artifactId>
  <version>0.0.1-SNAPSHOT</version>
   
  <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.1.RELEASE</version>
    </parent>
    <!-- 管理依赖 -->
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Finchley.M7</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <dependencies>
        <!-- SpringBoot整合Web组件 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!-- SpringBoot整合eureka客户端 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
 
    </dependencies>
    <!-- 注意： 这里必须要添加， 否者各种依赖有问题 -->
    <repositories>
        <repository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/libs-milestone</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </repository>
    </repositories>
</project>

　　Eureka

img

pom

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<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.toov5</groupId>
  <artifactId>SpringCloud-eureka-server</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.1.RELEASE</version>
    </parent>
    <!-- 管理依赖 -->
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Finchley.M7</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <dependencies>
        <!--SpringCloud eureka-server -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>
    </dependencies>
    <!-- 注意： 这里必须要添加， 否者各种依赖有问题 -->
    <repositories>
        <repository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/libs-milestone</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </repository>
    </repositories>
   
</project>

　　yml

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###eureka 服务端口号
server:
  port: 8100
###服务注册名称
eureka:
  instance:
  ##注册中心ip地址
    hostname: 127.0.0.1
###客户端调用地址
  client:
    serviceUrl:
      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
###因为该应用为注册中心，不会注册自己 （集群设为true）
    register-with-eureka: false
###因为自己为注册中心 ,不会去在该应用中的检测服务
    fetch-registry: false
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package com.toov5;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

@EnableEurekaServer   //开启注册中心
@SpringBootApplication 
public class AppEureka {
  
     public static void main(String[] args) {
           SpringApplication.run(AppEureka.class, args);
    }
    
}

启动访问：

img

img

img