（三）Spring Cloud Ribbon 实现服务访问的负载均衡
本章将讲解通过Ribbon实现负载均衡去访问多台Eureka Client中的服务
本项目是一个独立的maven项目，其中的多个module。
Eureka-Server，Eureka-Client ,Eureka-Ribbon_Client模块，其中Eureka-Client后续会以2个端口启动，并分别在Eureka-Server注册
1. 新建一个maven项目eureka-ribbon
2. 新建一个eureka-server
具体配置和上一篇类似
2.1 pom文件
<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-eureka-server</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> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-security</artifactId> <scope>compile</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-actuator</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-sleuth</artifactId> </dependency>
2.2 启动类
package com.devin.eurekaserver;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
@EnableEurekaServer
@SpringBootApplication
public class EurekaServerApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaServerApplication.class, args);
}
}
2.3 安全校验
package com.devin.eurekaserver.config;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
@EnableWebSecurity
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {
@Override
protected void configure(HttpSecurity http) throws Exception {
//关闭csrf
super.configure(http);
//开启认证
http.csrf().disable();
}
}
2.4 application.yml配置文件
eureka-server的启动端口为 7001
server:
port: 7001 #启动端口
spring:
#应用名称
application:
name: eureka-server
#安全配置
security:
basic:
enabled: true
user:
name: dev
password: 123456
#eureka配置
eureka:
server:
#设置扫描失效服务的间隔时间
eviction-interval-timer-in-ms: 20000
enable-self-preservation: true
instance:
hostname: localhost
leaseRenewalIntervalInSeconds: 10
health-check-url-path: /actuator/health
client:
register-with-eureka: false #false:不作为一个客户端注册到注册中心
fetch-registry: false #为true时，可以启动，但报异常：Cannot execute request on any known server
service-url:
defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
# health endpoint是否必须显示全部细节。默认情况下, /actuator/health 是公开的，并且不显示细节。
# 设置actuator开关
management:
security:
enabled: false
endpoints:
web:
exposure:
include: "*"
endpoint:
health:
show-details: ALWAYS
3. 创建eureka-client
eureka client后续将启动两个端口7002,7003，并分别在eureka-server注册
3.1 pom文件
<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> <version>2.1.8.RELEASE</version> </dependency>
3.2 启动类
package com.devin.eurekaclient;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
@EnableEurekaClient
@SpringBootApplication
public class EurekaClientApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaClientApplication.class, args);
}
}
3.3 新建一个Controller类，该类打印出eureka-client的启动端口
package com.devin.eurekaclient.controller;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
/**
* @author Devin Zhang
* @className HelloController
* @description TODO
* @date 2020/3/28 10:45
*/
@RestController
public class HelloController {
@Value("${server.port}")
private Integer port;
@GetMapping("/sayHello")
public String sayHello(String name) {
return "Hello ," + name + " ,this response is from eureka client port:" + port;
}
}
3.4 application.yml 配置文件
eureka:
auth:
user: dev
password: 123456
client:
serviceUrl:
defaultZone: http://${eureka.auth.user}:${eureka.auth.password}@localhost:7001/eureka/
instance:
#使用IP进行注册
prefer-ip-address: true
#配置实例的注册ID
instance-id: ${spring.cloud.client.ip-address}:${server.port}
#心跳时间，即服务续约间隔时间（缺省为30s）
lease-renewal-interval-in-seconds: 5
#发呆时间，即服务续约到期时间（缺省为90s）
lease-expiration-duration-in-seconds: 10
health-check-url-path: /actuator/health
server:
port: 7002
spring:
application:
name: eureka-client
启动eureka-client,分别在两个端口启动，这两个eureka-client实例将分别向 7001 eureka-server进行注册
java -jar eureka-client-0.0.1-SNAPSHOT.jar --server.port=7002
java -jar eureka-client-0.0.1-SNAPSHOT.jar --server.port=7003
4. eureka-client-ribbon
该服务将做为一个eureka-client进行注册，并通过RestTemplate对eureka-client进行负载均衡访问
4.1 pom.xml
<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-ribbon</artifactId> </dependency> <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> <version>2.1.8.RELEASE</version> </dependency>
4.2 启动类
package com.devin.eurekaribbonclient;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
@EnableEurekaClient
@SpringBootApplication
public class EurekaRibbonClientApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaRibbonClientApplication.class, args);
}
}
4.3 RestTemplate 配置类，支持负载均衡
package com.devin.eurekaribbonclient.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;
/**
* @author Devin Zhang
* @className RibbonConfig
* @description TODO
* @date 2020/3/28 11:51
*/
@Configuration
public class RibbonConfig {
@Bean
@LoadBalanced
public RestTemplate restTemplate() {
return new RestTemplate();
}
}
4.4 新建Service类，通过RestTemplate，负载均衡调用eureka-client的接口
package com.devin.eurekaribbonclient.service;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;
import javax.annotation.Resource;
/**
* @author Devin Zhang
* @className RibbonHelloService
* @description TODO
* @date 2020/3/28 11:54
*/
@Service
public class RibbonHelloService {
@Resource
private RestTemplate restTemplate;
public String sayHello(String name) {
return restTemplate.getForObject("http://EUREKA-CLIENT/sayHello?name=" + name, String.class);
}
}
4.5 Controller入口类，用于测试
package com.devin.eurekaribbonclient.controller;
import com.devin.eurekaribbonclient.service.RibbonHelloService;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.annotation.Resource;
/**
* @author Devin Zhang
* @className RibbonHelloController
* @description TODO
* @date 2020/3/28 11:57
*/
@RestController
public class RibbonHelloController {
@Resource
private RibbonHelloService ribbonHelloService;
@GetMapping("/sayHelloFromRibbon")
public String sayHello(String name) {
return ribbonHelloService.sayHello(name);
}
}
4.6 application.yml 配置文件
eureka:
auth:
user: dev
password: 123456
client:
serviceUrl:
defaultZone: http://${eureka.auth.user}:${eureka.auth.password}@localhost:7001/eureka/
instance:
#使用IP进行注册
prefer-ip-address: true
#配置实例的注册ID
instance-id: ${spring.cloud.client.ip-address}:${server.port}
#心跳时间，即服务续约间隔时间（缺省为30s）
lease-renewal-interval-in-seconds: 5
#发呆时间，即服务续约到期时间（缺省为90s）
lease-expiration-duration-in-seconds: 10
health-check-url-path: /actuator/health
server:
port: 7004
spring:
application:
name: eureka-ribbon-client
5. 测试结果
分别启动
eureka-server 7001
eureka-client 7002
eureka-client 7003
eureka-ribbon-client 7004
在注册中心http://localhost:7001可以看到，各个客户端已经进行了注册
验证负载均衡，访问 http://localhost:7004/sayHelloFromRibbon?name=devin ，可以看到对eureka-client的访问，会负载均衡到 7002,7003 对应的实例
