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

@Configuration
public class MySelfRule {

    @Bean
    public IRule getRandomRule(){
        return new RandomRule(); // 新建隨機訪問負(fù)載規(guī)則
    }
}

import com.xiao.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;

@SpringBootApplication
@EnableEurekaClient
@RibbonClient(name = "CLOUD-PAYMENT-SERVICE",configuration = MySelfRule.class)
public class OrderMain80 {
    public static void main(String[] args) {
        SpringApplication.run(OrderMain80.class,args);
    }
}

import com.netflix.client.config.IClientConfig;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class RoundRobinRule extends AbstractLoadBalancerRule {
    private AtomicInteger nextServerCyclicCounter;
    private static final boolean AVAILABLE_ONLY_SERVERS = true;
    private static final boolean ALL_SERVERS = false;
    private static Logger log = LoggerFactory.getLogger(RoundRobinRule.class);

    public RoundRobinRule() {
        this.nextServerCyclicCounter = new AtomicInteger(0);
    }

    public RoundRobinRule(ILoadBalancer lb) {
        this();
        this.setLoadBalancer(lb);
    }

    public Server choose(ILoadBalancer lb, Object key) {
        if (lb == null) {
            log.warn("no load balancer");
            return null;
        } else {
            Server server = null;
            int count = 0;

            while(true) {
                if (server == null && count++ < 10) {
                	// 獲取狀態(tài)為up的服務(wù)提供者
                    List<Server> reachableServers = lb.getReachableServers();
                    // 獲取所有的服務(wù)提供者
                    List<Server> allServers = lb.getAllServers();
                    int upCount = reachableServers.size();
                    int serverCount = allServers.size();
                    
                    if (upCount != 0 && serverCount != 0) {
                    	// 對取模獲得的下標(biāo)進(jìn)行獲取相關(guān)的服務(wù)提供者
                        int nextServerIndex = this.incrementAndGetModulo(serverCount);
                        server = (Server)allServers.get(nextServerIndex);

                        if (server == null) {
                            Thread.yield();
                        } else {
                            if (server.isAlive() && server.isReadyToServe()) {
                                return server;
                            }

                            server = null;
                        continue;
                    }

                    log.warn("No up servers available from load balancer: " + lb);
                    return null;
                }

                if (count >= 10) {
                    log.warn("No available alive servers after 10 tries from load balancer: " + lb);
                }

                return server;
            }
        }
    }

    private int incrementAndGetModulo(int modulo) {
        int current;
        int next;
        do {
        	// 先加一再取模
            current = this.nextServerCyclicCounter.get();
            next = (current + 1) % modulo;
            // CAS判斷，如果判斷成功就返回true，否則就一直自旋
        } while(!this.nextServerCyclicCounter.compareAndSet(current, next));

        return next;
    }
}

@GetMapping(value = "/payment/lb")
public String getPaymentLB(){
      return ServerPort;
}

import org.springframework.cloud.client.ServiceInstance;

import java.util.List;

public interface LoadBalancer {
    //收集服務(wù)器總共有多少臺能夠提供服務(wù)的機器，并放到list里面
    ServiceInstance instances(List<ServiceInstance> serviceInstances);

}

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);

    //坐標(biāo)
    private final int getAndIncrement(){
        int current;
        int next;
        do {
            current = this.atomicInteger.get();
            next = current >= 2147483647 ? 0 : current + 1;
        }while (!this.atomicInteger.compareAndSet(current,next));  //第一個參數(shù)是期望值，第二個參數(shù)是修改值是
        System.out.println("*******第幾次訪問，次數(shù)next: "+next);
        return next;
    }

    @Override
    public ServiceInstance instances(List<ServiceInstance> serviceInstances) {  //得到機器的列表
        int index = getAndIncrement() % serviceInstances.size(); //得到服務(wù)器的下標(biāo)位置
        return serviceInstances.get(index);
    }
}

import com.xiao.cloud.entities.CommonResult;
import com.xiao.cloud.entities.Payment;
import com.xiao.cloud.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.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import javax.annotation.Resource;
import java.net.URI;
import java.util.List;

@RestController
@Slf4j
public class OrderController {

    // public static final String PAYMENT_URL = "http://localhost:8001";
    public static final String PAYMENT_URL = "http://CLOUD-PAYMENT-SERVICE";

    @Resource
    private RestTemplate restTemplate;

    @Resource
    private LoadBalancer loadBalancer;

    @Resource
    private DiscoveryClient discoveryClient;

    @GetMapping("/consumer/payment/create")
    public CommonResult<Payment>   create( Payment payment){
        return restTemplate.postForObject(PAYMENT_URL+"/payment/create",payment,CommonResult.class);  //寫操作
    }

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

    @GetMapping("/consumer/payment/getForEntity/{id}")
    public CommonResult<Payment> getPayment2(@PathVariable("id") Long id){
        ResponseEntity<CommonResult> entity = restTemplate.getForEntity(PAYMENT_URL+"/payment/get/"+id,CommonResult.class);
        if (entity.getStatusCode().is2xxSuccessful()){
            //  log.info(entity.getStatusCode()+"\t"+entity.getHeaders());
            return entity.getBody();
        }else {
            return new CommonResult<>(444,"操作失敗");
        }
    }

    @GetMapping(value = "/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);
    }
}