SpringCloud:使用spring cloud LoadBalancer作为负载均衡器并使用随机策略
1.在配置文件里进行配置：
spring.cloud.loadbalancer.ribbon.enabled=false
完整的application.properties如下：
server.port=8088
spring.application.name=springboot
spring.datasource.url=jdbc:mysql://139.198.xx.xx/xxx
spring.datasource.username=root
spring.datasource.password=MyPassword
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
eureka.client.serviceUrl.defaultZone=http://139.198.xx.xx:8761/eureka/
eureka.instance.preferIpAddress=true
spring.cloud.loadbalancer.ribbon.enabled=false
spring.cloud.loadbalancer.enabled=true
2.在pom.xml中增加load balancer依赖
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-loadbalancer</artifactId>
</dependency>
完整pom.xml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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>cn.edu.tju</groupId>
<artifactId>springcloudloadbalancer</artifactId>
<version>1.0-SNAPSHOT</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.3.7.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Hoxton.SR12</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<exclusions>
<exclusion>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>2.8.6</version>
</dependency>
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>1.3.2</version>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-loadbalancer</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.30</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.springframework.cloud/spring-cloud-starter-netflix-eureka-client -->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
<version>2.1.0.RELEASE</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
3.配置RestTemplate
package cn.edu.tju.config;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;
@Configuration
public class RestConfig {
@Bean
@LoadBalanced
public RestTemplate getRestTemplate(){
return new RestTemplate();
}
}
4.创建随机策略配置类：
package cn.edu.tju.config;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.loadbalancer.core.RandomLoadBalancer;
import org.springframework.cloud.loadbalancer.core.ReactorLoadBalancer;
import org.springframework.cloud.loadbalancer.core.ServiceInstanceListSupplier;
import org.springframework.cloud.loadbalancer.support.LoadBalancerClientFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;
public class LoadBalancerConfig {
@Bean
ReactorLoadBalancer<ServiceInstance> randomLoadBalancer(Environment environment,
LoadBalancerClientFactory loadBalancerClientFactory) {
String name = environment.getProperty(LoadBalancerClientFactory.PROPERTY_NAME);
return new RandomLoadBalancer(loadBalancerClientFactory
.getLazyProvider(name, ServiceInstanceListSupplier.class),
name);
}
}
5.在启动类加注解：
@LoadBalancerClient(name = "demoservice", configuration = LoadBalancerConfig.class)
其中name属性为调用的微服务的名称，configuration属性为上一步定义的随机负载均衡策略类
6.创建控制器类，通过RestTemplate来调用微服务：
package cn.edu.tju.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;
@RestController
public class TestController {
@Autowired
private RestTemplate restTemplate;
@RequestMapping("/hi")
public String test(){
String result="";
for(int i=0;i<100;i++){
result=restTemplate.getForObject("http://demoservice/test",String.class);
System.out.println(result);
}
return result;
}
}
其中demoservice是注册到eureka中的一个微服务
7.访问http://localhost:8088/hi,截图如下，可以看到是随机访问了两个微服务实例
8.如果想换成轮询(RoundRobin)策略，只需创建配置类，并在启动类上修改配置类名：
package cn.edu.tju.config;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.loadbalancer.core.RandomLoadBalancer;
import org.springframework.cloud.loadbalancer.core.RoundRobinLoadBalancer;
import org.springframework.cloud.loadbalancer.core.ReactorLoadBalancer;
import org.springframework.cloud.loadbalancer.core.ServiceInstanceListSupplier;
import org.springframework.cloud.loadbalancer.support.LoadBalancerClientFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;
public class LoadBalancerConfig2 {
@Bean
ReactorLoadBalancer<ServiceInstance> roundLoadBalancer(Environment environment,
LoadBalancerClientFactory loadBalancerClientFactory) {
String name = environment.getProperty(LoadBalancerClientFactory.PROPERTY_NAME);
return new RoundRobinLoadBalancer(loadBalancerClientFactory
.getLazyProvider(name, ServiceInstanceListSupplier.class),
name);
}
}