SpringCloud Ribbon 客户端负载均衡

简介：是一个基于Http、tcp协议的客户端负载均衡工具，当浏览器向后端发送请求时，选取Eureka Server 中的可用服务提供者列表，根据负载均衡策略，选取一个可用服务发送请求

负载均衡策略：轮询（RoundRobin）、随机（Radom）、请求数最少（BestAvailable）

代码示例如下：

注：此示例基于 springboot1.5.10

1、eureka server 此模块内容在此省略

2、服务提供者模块

添加依赖：只需添加必要的依赖，无需添加特定依赖

<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>
            <version>1.4.3.RELEASE</version>
        </dependency>

application配置：

server:
  port: 7904 #程序启动端口，也是Tomcat端口
spring:
  application:
    name: provider-user #应用别名

eureka:
  client:
    service-url:
      defaultZone: http://user:123@localhost:10000/eureka
  instance:
      instance-id: ${spring.cloud.client.ipAddress}:${spring.application.name}:${spring.application.instance_id:${server.port}}
      prefer-ip-address: true #是否以ip显示host

启动类：

@SpringBootApplication
@EnableEurekaClient //启用eureka客户端
public class providerApplication
{
    public static void main( String[] args )
    {
        SpringApplication.run(providerApplication.class,args);
        System.out.println("provider-user start-up success");
    }
}

3、服务消费者模块

添加依赖：与服务提供者相同

application配置

server:
  port: 8900 #程序启动端口，也是Tomcat端口
spring:
  application:
    name: customer-order-ribbon #应用别名

eureka:
  client:
    service-url:
      defaultZone: http://user:123@localhost:10000/eureka
  instance:
    instance-id: ${spring.cloud.client.ipAddress}:${spring.application.name}:${spring.application.instance_id:${server.port}}
    prefer-ip-address: true
#      eureka.instance.preferIpAddress=true

#eureka.instance=instance-id=${spring.cloud.client.ipAddress}:${spring.application.name}:${spring.application.instance_id:${server.port}}
#user:
#  url: http://localhost:7900/user/

配置类

@Configuration
public class TestRibbonConfig {
    @Autowired
    IClientConfig iClientConfig;

    @Bean
    public IRule testRibbon(IClientConfig iClientConfig){
        return new RandomRule();
    }

}

　启动类

@SpringBootApplication
@EnableEurekaClient
@RibbonClient(name="PROVIDER-USER",configuration = TestRibbonConfig.class) //启用ribbon,并对 PROVIDER-USER 进行负载均衡
public class customerApplication
{
    @Bean
    @LoadBalanced
    public RestTemplate getTemp(){
        return new RestTemplate();
    }
    public static void main( String[] args )
    {
        SpringApplication.run(customerApplication.class,args);
        System.out.println("customer start-up success");
    }
}

Controller

@RestController
public class CustomeController {
    @Autowired
    private EurekaClient eurekaClient;

    @Autowired
    private RestTemplate restTemplate;//springboot提供的用于访问rest接口的对象

    @Autowired
    private LoadBalancerClient loadBalancerClient;

    @GetMapping("/testRibbon")
    public String testRibbon(){
        ServiceInstance choose = loadBalancerClient.choose("PROVIDER-USER");
        System.err.println("testRibbon:serviceId"+choose.getServiceId()+",host:"+choose.getHost()+",port:"+choose
                .getPort());
        return "testRibbon:"+choose.getPort();
    }
}

　注：如果需要访问其他微服务模块，可使用rest接口