05Ribbon负载均衡服务调用

package com.ray.myrule;

import com.netflix.loadbalancer.IRule;
import com.netflix.loadbalancer.RandomRule;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * @Description: Ribbon 规则类
 * @Author Administrator
 * @Date 2020/10/11 14:20
 * @Version 1.0
 */
@Configuration
public class MySelfRule {

    @Bean
    public IRule myRule() {
        return new RandomRule(); // 定义为随机
    }
}

package com.ray.springcloud.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;

/**
 * @Description: 相当于封装了 HttpClient
 * @Author Ray
 * @Date 2020/10/07 11:40
 * @Version 1.0
 */
@Configuration
public class RestTemplateConfig {

    @Bean
    @LoadBalanced // 赋予负载均衡能力
    public RestTemplate getRestTemplate() {
        return new RestTemplate();
    }
}

package com.ray.springcloud;

import com.ray.myrule.MySelfRule;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.ribbon.RibbonClient;

/**
 * @Description:
 * @Author Ray
 * @Date 2020/10/07 11:41
 * @Version 1.0
 */
@SpringBootApplication
@EnableEurekaClient // 客户端
@RibbonClient(name = "CLOUD-PAYMENT-SERVICE", configuration = MySelfRule.class) // 负载规则替换，默认轮询
public class OrderMain80 {

    public static void main(String[] args) {
        SpringApplication.run(OrderMain80.class, args);
    }
}

@GetMapping("/lb")
public String getPaymentLB() {
    return port;
}

package com.ray.springcloud.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;

/**
 * @Description: 相当于封装了 HttpClient
 * @Author Ray
 * @Date 2020/10/07 11:40
 * @Version 1.0
 */
@Configuration
public class RestTemplateConfig {

    @Bean
    //@LoadBalanced // 赋予负载均衡能力
    public RestTemplate getRestTemplate() {
        return new RestTemplate();
    }
}

package com.ray.springcloud.lb;

import org.springframework.cloud.client.ServiceInstance;

import java.util.List;

/**
 * @Description: 自己实现轮询算法 - 接口
 * @Author Administrator
 * @Date 2020/10/11 14:57
 * @Version 1.0
 */
public interface LoadBalancer {

    /**
     * 得到目前注册中心可以使用的集群机器，放到集合里面
     */
    ServiceInstance instances(List<ServiceInstance> serviceInstances);
}

package com.ray.springcloud.lb;

import lombok.extern.slf4j.Slf4j;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.stereotype.Component;

import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * @Description: 自己实现轮询算法 - 实现
 * @Author Administrator
 * @Date 2020/10/11 15:14
 * @Version 1.0
 */
@Slf4j
@Component
public class MyLB implements LoadBalancer {

    // 默认从0开始
    private AtomicInteger atomicInteger = new AtomicInteger(0);

    /**
     * 获取当前的次数
     */
    public final int getAndIncrement() {
        int current;
        int next;
        do {
            // 得到当前的值
            current = this.atomicInteger.get();
            // 考虑防止越界，实际肯定不会这么大
            next = current >= Integer.MAX_VALUE ? 0 : current + 1;
            // 如果值不相同，不停自旋，直到相同 compareAndSet
            log.info("<<<<< 自旋中 current: [{}] -- next: [{}]", current, next);
        } while (!this.atomicInteger.compareAndSet(current, next));
        log.info(">>>>> 访问次数 next: [{}]", next);
        return next;
    }

    /**
     * 第几次请求数
     */
    @Override
    public ServiceInstance instances(List<ServiceInstance> serviceInstances) {
        int index = getAndIncrement() % serviceInstances.size();
        return serviceInstances.get(index);
    }
}