springCloud(五) RestTemplate通信 和 Ribbon 客户端负载均衡

1.客户端负载均衡图解

微服务端进行通信

使用RestTemplate 和 LoadBalanced 注解通信

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 https://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>2.3.0.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.itlaoqi.springcloud</groupId>
    <artifactId>member-service</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>member-service</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Hoxton.SR4</spring-cloud.version>
    </properties>

    <repositories>
        <repository>
            <id>aliyun-nexus</id>
            <url>http://maven.aliyun.com/nexus/content/groups/public/</url>
        </repository>
        <repository>
            <id>aliyun-public</id>
            <url>https://maven.aliyun.com/repository/public</url>
        </repository>

        <repository>
            <id>aliyun-jcenter</id>
            <url>https://maven.aliyun.com/repository/jcenter</url>
        </repository>
    </repositories>
    <pluginRepositories>
        <pluginRepository>
            <id>aliyun-plugin</id>
            <url>http://maven.aliyun.com/nexus/content/groups/public/</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </pluginRepository>
    </pluginRepositories>


    <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>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </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: 8082
spring:
  application:
    name: member-service
eureka:
  client:
    service-url:
      defaultZone:
        http://localhost:8761/eureka/

3. application.java

package com.itlaoqi.springcloud.memberservice;

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 MemberServiceApplication {

    @Bean
    @LoadBalanced  // 负载均衡注解，通过restTemplate 发送的请求默认带有负载均衡的特性(轮询)
    public RestTemplate restTemplatem(){
        return new RestTemplate();
    }

    /*
        针对全局进行配置, 优先级最高
     */
    @Bean
    public IRule ribbonRule(){
        return new RoundRobinRule();
    }

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

}

4. MemberController.java

package com.itlaoqi.springcloud.memberservice.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import java.util.Map;

@RestController
public class MemberController {

    @Autowired
    private RestTemplate restTemplate;

    /**
     *  RestTemplate 负载均衡 格式要求
     *  http://微服务id/webapi地址
     */
    @RequestMapping("/borrow")
    public Map<String,Object> borrow(){
        return restTemplate.getForObject("http://book-service/test", Map.class);
    }
}

ribbon 负载算法