第六章 SpringCloud之Ribbon负载均衡

###################使用默认的负载均衡(轮询)#############################

1、pom.xml

<?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>2.1.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.test</groupId>
    <artifactId>eureka-client-ribbon</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>eureka-client-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-server</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>

2、application.yml

server:
  port: 8665
user:
  userServicePath: http://localhost:8663/user/

spring:
  application:
    name: eureka-client-ribbon
eureka:
  instance:
    hostname: localhost
    prefer-ip-address: true
    instance-id: ${spring.application.name}:${spring.application.instance_id:${server.port}}
  client:
    serviceUrl:
      defaultZone: http://${eureka.instance.hostname}:8661/eureka

3、对RestTemplate添加注解

package com.test.eurekaclientribbon;

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

@SpringBootApplication
@EnableEurekaClient
public class EurekaClientRibbonApplication {

    @Bean
    @LoadBalanced  //使restTemplate具备负载均衡的作用
    public RestTemplate restTemplate(){
        return  new RestTemplate();
    }
    public static void main(String[] args) {
        SpringApplication.run(EurekaClientRibbonApplication.class, args);
    }

}

4、使用restTemplate对象远程调用服务

package com.test.eurekaclientribbon.controller;

import com.test.eurekaclientribbon.entity.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

/**
 * Ribbon使用步骤：
 * 全局配置
 *      1、添加依赖
 *      2、配置application.yml文件
 *      3、对启动类中的RestTemplate添加@LoadBalanced注解，使得RestTemplate对象具备负载均衡能力
 *      4、请求路径为：被调用方的地址，但必须将被调用方的ip地址改为virtualIp
 *          例如   restTemplate.getForObject("http://eureka-client-user/user/"+id, User.class);
 *                被调用方URL:http://192.168.137.1:8663/user/
 *                       现为：http://eureka-client-user/user/
 */
@RestController
public class MovieController {
    @Autowired
    private RestTemplate restTemplate;

    @Value("${user.userServicePath}")
    private String userServicePath;

   /* @Autowired
    private LoadBalancerClient loadBalancerClient;*/

    @GetMapping("/movie/{id}")
    public User findById(@PathVariable Long id) {
        //请用虚拟ip
        return restTemplate.getForObject("http://eureka-client-user/user/"+id, User.class);
    }

    /**
     * 配置单一的方法进行轮询
     * @return
     */
   /* @GetMapping("/test")
    public String test() {
        //请用虚拟ip
        ServiceInstance serviceInstance =loadBalancerClient.choose("eureka-client-user");
        System.out.println(serviceInstance.getHost()+":"+serviceInstance.getPort());
        return "1";
    }*/
}

5、访问

http://localhost:8661/  #查看eureka
http://192.168.137.1:8663/user/2    #确保自己调用可以访问
http://192.168.137.1:8665/movie/4  #远程调用测试

###################配置对单一的方法进行轮询(使用loadBalancerClient)########################

1、针对第一个步骤中的(4),进行修改

package com.test.eurekaclientribbon.controller;

import com.test.eurekaclientribbon.entity.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

/**
 * Ribbon使用步骤：
 * 全局配置
 *      1、添加依赖
 *      2、配置application.yml文件
 *      3、对启动类中的RestTemplate添加@LoadBalanced注解，使得RestTemplate对象具备负载均衡能力
 *      4、请求路径为：被调用方的地址，但必须将被调用方的ip地址改为virtualIp
 *          例如   restTemplate.getForObject("http://eureka-client-user/user/"+id, User.class);
 *                被调用方URL:http://192.168.137.1:8663/user/
 *                       现为：http://eureka-client-user/user/
 */
@RestController
public class MovieController {
   /* @Autowired
    private RestTemplate restTemplate;
*/
    @Value("${user.userServicePath}")
    private String userServicePath;

    @Autowired
    private LoadBalancerClient loadBalancerClient;

   /* @GetMapping("/movie/{id}")
    public User findById(@PathVariable Long id) {
        //请用虚拟ip
        return restTemplate.getForObject("http://eureka-client-user/user/"+id, User.class);
    }*/

    /**
     * 配置单一的方法进行轮询
     * @return
     */
    @GetMapping("/test")
    public String test() {
        //请用虚拟ip
        ServiceInstance serviceInstance =loadBalancerClient.choose("eureka-client-user");
        System.out.println(serviceInstance.getHost()+":"+serviceInstance.getPort());
        return "1";
    }
}

###################全局修改负载均衡方式########################

1、针对(2)application.yml文件添加下面配置

server:
  port: 8665
user:
  userServicePath: http://localhost:8663/user/

spring:
  application:
    name: eureka-client-ribbon
eureka:
  instance:
    hostname: localhost
    prefer-ip-address: true
    instance-id: ${spring.application.name}:${spring.application.instance_id:${server.port}}
  client:
    serviceUrl:
      defaultZone: http://${eureka.instance.hostname}:8661/eureka
eureka-client-user:  #远程服务虚拟主机名
  ribbon:
    NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RoundRobinRule  #随机方式
    #可以通过IRule类查看负载均衡方式
    #RoundRobinRule  轮询
    #RandomRule 随机

###################编写Configuration文件指定负载均衡方式########################

1、创建一个配置类

package com.test.eurekaclientribbon.config;
import com.netflix.client.config.IClientConfig;
import com.netflix.loadbalancer.IRule;
import com.netflix.loadbalancer.RandomRule;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class RibbonConfig {
    @Bean
    public IRule ribbonRule() {
            return new RandomRule();
        }
}

2、在启动类上添加注解

package com.test.eurekaclientribbon;

import com.test.eurekaclientribbon.config.RibbonConfig;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.ribbon.RibbonClient;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableEurekaClient
@RibbonClient(name = "eureka-client-user",configuration = RibbonConfig.class)  //表示eureka-client-user主机使用这个规则
public class EurekaClientRibbonApplication {

    @Bean
    @LoadBalanced  //使restTemplate具备负载均衡的作用
    public RestTemplate restTemplate(){
        return  new RestTemplate();
    }
    public static void main(String[] args) {
        SpringApplication.run(EurekaClientRibbonApplication.class, args);
    }

}