Ribbon 自定义负载规则（轮询）

• 消费者服务项目结构

• 注入RestTemplate

package com.laoxu.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;

@Configuration
public class ApplicationContextConfig {
    @Bean
//    @LoadBalanced
    public RestTemplate getRestTemplate(){
        return new RestTemplate();
    }
}

• 定义负载均衡接口

package com.laoxu.springcloud.lb;

import org.springframework.cloud.client.ServiceInstance;

import java.util.List;

public interface LoadBalancer {

    ServiceInstance instances(List<ServiceInstance> serviceInstances);

}

• 自定义负载均衡实现类

package com.laoxu.springcloud.lb;

import org.springframework.cloud.client.ServiceInstance;
import org.springframework.stereotype.Component;

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

@Component
public class MyLB implements LoadBalancer {

    private AtomicInteger atomicInteger = new AtomicInteger(0);

    public final int getAndIncrement(){
        int current;
        int next;
        do {
            current = this.atomicInteger.get();
            next = current >= 2147483647 ? 0 : current + 1;

        }while (!this.atomicInteger.compareAndSet(current, next));
        System.out.println("*****next: " + next);
        return next;
    }

    public ServiceInstance instances(List<ServiceInstance> serviceInstances) {
        // 当前服务提供者下标 = 获取当前自增数 % 服务总数
        int index = getAndIncrement() % serviceInstances.size();
        // 获取当前服务提供者
        return serviceInstances.get(index);
    }
}

• 测试负载均衡

package com.laoxu.springcloud.controller;

import com.laoxu.springcloud.entities.CommonResult;
import com.laoxu.springcloud.entities.Payment;
import com.laoxu.springcloud.lb.LoadBalancer;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import java.net.URI;
import java.util.List;

@RestController
@Slf4j
public class OrderController {

    @Autowired
    private RestTemplate restTemplate;
    @Autowired
    private LoadBalancer loadBalancer;
    @Autowired
    private DiscoveryClient discoveryClient;

//    private static final String PAYMENT_URL = "http://localhost:8001";
    private static final String PAYMENT_URL = "http://CLOUD-PAYMENT-SERVICE";
    @PostMapping("/consumer/payment/create")
    public CommonResult<Payment> create(Payment payment){
        return restTemplate.postForObject(PAYMENT_URL + "/payment/create", payment, CommonResult.class);
    }

    @GetMapping("/consumer/payment/get/{id}")
    public CommonResult<Payment> getPaymentById(@PathVariable("id") Long id){
        return restTemplate.getForObject(PAYMENT_URL + "/payment/get/" +id, CommonResult.class);
    }

    // 测试自定义负载均衡
    @GetMapping("/consumer/payment/lb")
    public String getPaymentLB(){
        List<ServiceInstance> instances = discoveryClient.getInstances("CLOUD-PAYMENT-SERVICE");
        if(instances == null || instances.size() <= 0){
            return null;
        }
        ServiceInstance serviceInstance = loadBalancer.instances(instances);
        URI uri = serviceInstance.getUri();
        return restTemplate.getForObject(uri + "/payment/lb", String.class);
    }

}

• 服务提供者8001和8002编写测试接口

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

• 访问：http://localhost/consumer/payment/lb
• 结果：每次请求分别轮询两台服务返回：8001和8002