SpringCloud如何实现Zuul集群(负载均衡)

#会员服务
server:
  port: 8082
spring:
  application:
    name: member-service    #服务名
#Eureka配置
eureka:
  client:
    service-url:
      defaultZone: http://127.0.0.1:8761/eureka/     #注册中心的地址

#订单服务
server:
  port: 8081
spring:
  application:
    name: order-service   #服务名
#Eureka配置
eureka:
  client:
    service-url:
      defaultZone: http://127.0.0.1:8761/eureka/      #注册中心地址

#配置Zuul端口
server:
  port: 81
spring:
  application:
    name: zull-gateway-service    #服务名
#Eureka配置
eureka:
  client:
    service-url:
      defaultZone: http://127.0.0.1:8761/eureka/    #注册中心地址
      
# 配置网关反向代理，例如访问/api-member/** 直接重定向到member-service服务,实现路由转发，隐藏服务的真实ip(服务都实在内网中)
#zull根据服务名，去Eureka获取服务真实地址，并通过本地转发，而且默认开启Ribbon实现负载均衡
#默认读取Eureka注册列表 默认30秒间隔  
zuul:
 routes:
   api-a: #会员服务网关配置
     path: /api-member/**   #访问只要是/api-member/ 开头的直接转发到member-service服务
     #服务名
     serviceId: member-service
   api-b: #订单服务网关配置
     path: /api-order/**
     serviceId: order-service

package com.example.zuul.filter;
import com.netflix.zuul.ZuulFilter;
import com.netflix.zuul.context.RequestContext;
import com.netflix.zuul.exception.ZuulException;
import io.micrometer.core.instrument.util.StringUtils;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
import javax.servlet.http.HttpServletRequest;
@Component
public class TokenFilter extends ZuulFilter {
	//统计当前Zuul调用次数
    int count = 0;
    
	//获取Zuul服务端口号
    @Value("${server.port}")
    private String prot;
    
    /**
     * 指定该Filter的类型
     * ERROR_TYPE = "error";
     * POST_TYPE = "post";
     * PRE_TYPE = "pre";
     * ROUTE_TYPE = "route";
     */
    @Override
    public String filterType() {
        System.out.println("filterType()...");
        return "pre";
    }
    /**
     * 指定该Filter执行的顺序（Filter从小到大执行）
     * DEBUG_FILTER_ORDER = 1;
     * FORM_BODY_WRAPPER_FILTER_ORDER = -1;
     * PRE_DECORATION_FILTER_ORDER = 5;
     * RIBBON_ROUTING_FILTER_ORDER = 10;
     * SEND_ERROR_FILTER_ORDER = 0;
     * SEND_FORWARD_FILTER_ORDER = 500;
     * SEND_RESPONSE_FILTER_ORDER = 1000;
     * SIMPLE_HOST_ROUTING_FILTER_ORDER = 100;
     * SERVLET_30_WRAPPER_FILTER_ORDER = -2;
     * SERVLET_DETECTION_FILTER_ORDER = -3;
     */
    @Override
    public int filterOrder() {
        System.out.println("filterOrder()...");
        return 0;
    }
    /**
     * 指定需要执行该Filter的规则
     * 返回true则执行run()
     * 返回false则不执行run()
     */
    @Override
    public boolean shouldFilter() {
        System.out.println("shouldFilter()...");
        return true;
    }
    /**
     * 该Filter具体的执行活动
     */
    @Override
    public Object run() throws ZuulException {
        // 获取上下文
        //RequestContext currentContext = RequestContext.getCurrentContext();
        //HttpServletRequest request = currentContext.getRequest();
        //获取userToken
       // String userToken = request.getParameter("userToken");
        //System.out.println("userToken: "+userToken);
        //if (StringUtils.isEmpty(userToken)) {
            //不会继续执行调用服务接口，网关直接响应给客户端
            //currentContext.setSendZuulResponse(false);
            //currentContext.setResponseStatusCode(401);
           // currentContext.setResponseBody("userToken is Null");
           // return null;
       // }else if(!userToken.equals("10010")){
           // currentContext.setSendZuulResponse(false);
            //currentContext.setResponseStatusCode(401);
            //currentContext.setResponseBody("userToken is Error");
            //return null;
        //}
        // 否则正常执行业务逻辑，调用服务.....
        System.out.println("访问Zuul网关端口为："+prot +"（total："+ ( count++) +"）");
        return null;
    }
}

#配置上游服务器 集群，默认轮询机制
	upstream backServer{
		server 127.0.0.1:81;
		server 127.0.0.1:82;
		# 补充: backup表示从服务器或者叫备用服务器  只有当主服务器（81、82端口）都不能访问时才会访问此（83端口）备用服务器 当主服务器恢复正常后 则访问主服务器
		#server 127.0.0.1:83 backup;
	}
    server {
        listen       80;
        server_name  localhost;
        #charset koi8-r;
        #access_log  logs/host.access.log  main;
        location / {
            ##root   html;
			#指定上游负载均衡服务器
			proxy_pass http://backServer/;
            index  index.html index.htm;
        }
    }

upstream backServer{
		server 127.0.0.1:81;
		server 127.0.0.1:82;
		# 补充: backup表示从服务器或者叫备用服务器  只有当主服务器（81、82端口）都不能访问时才会访问此（83端口）备用服务器 当主服务器恢复正常后 则访问主服务器
		server 127.0.0.1:83 backup;
	}

upstream backServer{
		server 127.0.0.1:81;
		server 127.0.0.1:82;
		server 127.0.0.1:83 backup;
	}
	
location / {
        proxy_pass   http://backServer/;
        proxy_redirect  default;
	    proxy_connect_timeout 1;  # 超时1s则转发到其他服务，宕机情况下也适用
	    proxy_read_timeout 1;
	    proxy_send_timeout 1;