05-LoadBalancer负载均衡

目前主流的负载方案分为以下两种：

集中式负载均衡，在消费者和服务提供方中间使用独立的代理方式进行负载，有硬件的（比如 F5），也有软件的（比如 Nginx）。

客户端根据自己的请求情况做负载均衡，LoadBalancer、Ribbon 就属于客户端自己做负载均衡。

2、快速开始

废话不多少，上代码。

pom.xml

maven依赖配置文件，如下：

<?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 "> <modelVersion>4.0.0</modelVersion> <groupId>com.mindasoft</groupId> <artifactId>spring-cloud-ribbon-consumer</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>spring-cloud-ribbon-consumer</name> <description>Demo project for Spring Boot</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.6.4</version> <relativePath/> <!-- lookup parent from repository --> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>1.8</java.version> <spring-cloud.version>2021.0.1</spring-cloud.version> </properties> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</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> <repositories> <repository> <id>nexus-aliyun</id> <name>Nexus aliyun</name> <url>https://maven.aliyun.com/repository/public</url> <layout>default</layout> <snapshots> <enabled>false</enabled> </snapshots> <releases> <enabled>true</enabled> </releases> </repository> </repositories> <pluginRepositories> <pluginRepository> <id>nexus-aliyun</id> <name>Nexus aliyun</name> <url>https://maven.aliyun.com/repository/public</url> <snapshots> <enabled>false</enabled> </snapshots> <releases> <enabled>true</enabled> </releases> </pluginRepository> </pluginRepositories> </project>

上面配置文件，我们没有新增LoadBalancer的配置，其实spring-cloud-starter-netflix-eureka-client已经依赖了一个具体实现，在老版本的是Ribbon，新的版本是Spring自己实现的loadbalancer，如下：。

<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-loadbalancer</artifactId> </dependency>

所以不需要格外添加配置。

application.properties

服务配置文件，也可以用yml，如下：

server.port=9003 # 服务注册中心地址 eureka.client.service-url.defaultZone=http://localhost:9000/eureka/ # 服务名称 spring.application.name=loadbalancer-customer LoadBalancerConsumerApplication

服务启动类，如下：

import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.client.discovery.EnableDiscoveryClient; import org.springframework.cloud.client.loadbalancer.LoadBalanced; import org.springframework.context.annotation.Bean; import org.springframework.web.client.RestTemplate; @EnableDiscoveryClient // Eureka Discovery Client 标识 @SpringBootApplication public class LoadBalancerConsumerApplication { @Bean @LoadBalanced // 开启负载均衡的功能 RestTemplate restTemplate() { return new RestTemplate(); } public static void main(String[] args) { SpringApplication.run(SpringCloudRibbonConsumerApplication.class, args); } }