解析：首先会员服务在注册中心上注册，这个时候就在zookeeper上生成几个临时节点，节点名是/member/8080和/member/8081,值是127.0.0.1:8080,127.0.0.1:8081（zookeeeper每个节点都有节点名和节点值），/member是会员服务的入口，这个时候订单服务调用会员服务，使用本地负载均衡策略，如下所示：

 

使用Zookeeper实现负载均衡原理

思路
使用Zookeeper实现负载均衡原理，服务器端将启动的服务注册到，zk注册中心上，采用临时节点。客户端从zk节点上获取最新服务节点信息，本地使用负载均衡算法，随机分配服务器。
Maven依赖

    <dependencies>
		<dependency>
			<groupId>com.101tec</groupId>
			<artifactId>zkclient</artifactId>
			<version>0.8</version>
		</dependency>
	</dependencies>

创建Server服务端

ZkServerScoekt服务

package com.itmayiedu;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import org.I0Itec.zkclient.ZkClient;
//##ServerScoekt服务端
public class ZkServerScoekt implements Runnable {
	private int port = 18080;
	public static void main(String[] args) throws IOException {
		int port = 18080;
		ZkServerScoekt server = new ZkServerScoekt(port);
		Thread thread = new Thread(server);
		thread.start();
	}
	public ZkServerScoekt(int port) {
		this.port = port;
	}
	// 将服务信息注册到注册中心上去
	public void regServer() {
		ZkClient zkClient = new ZkClient("127.0.0.1:2181", 6000, 1000);
		String path = "/member/server-" + port;
		if (zkClient.exists(path)) {
			zkClient.delete(path);
		}
		String value="127.0.0.1:" + port;
		zkClient.createEphemeral(path, "127.0.0.1:" + port);
		System.out.println("##服务注册成功###"+value);
	}
	public void run() {
		ServerSocket serverSocket = null;
		try {
			serverSocket = new ServerSocket(port);
			regServer();
			System.out.println("Server start port:" + port);
			Socket socket = null;
			while (true) {
				socket = serverSocket.accept();
				new Thread(new ServerHandler(socket)).start();
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				if (serverSocket != null) {
					serverSocket.close();
				}
			} catch (Exception e2) {

			}
		}
	}
}

ServerHandler.java

package com.itmayiedu;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;

//ServerHandler
public class ServerHandler implements Runnable {
	private Socket socket;

	public ServerHandler(Socket socket) {
		this.socket = socket;
	}

	public void run() {
		BufferedReader in = null;
		PrintWriter out = null;
		try {
			in = new BufferedReader(new InputStreamReader(this.socket.getInputStream()));
			out = new PrintWriter(this.socket.getOutputStream(), true);
			String body = null;
			while (true) {
				body = in.readLine();
				if (body == null)
					break;
				System.out.println("Receive : " + body);
				out.println("Hello, " + body);
			}

		} catch (Exception e) {
			if (in != null) {
				try {
					in.close();
				} catch (IOException e1) {
					e1.printStackTrace();
				}
			}
			if (out != null) {
				out.close();
			}
			if (this.socket != null) {
				try {
					this.socket.close();
				} catch (IOException e1) {
					e1.printStackTrace();
				}
				this.socket = null;
			}
		}
	}
}

ZkServerClient

package com.itmayiedu;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;
import org.I0Itec.zkclient.IZkChildListener;
import org.I0Itec.zkclient.ZkClient;
public class ZkServerClient {
	// 获取所有的服务地址
	public static List<String> listServer = new ArrayList<String>();
	public static void main(String[] args) {
		initServer();
		ZkServerClient client = new ZkServerClient();
		BufferedReader console = new BufferedReader(new InputStreamReader(System.in));
		while (true) {
			String name;
			try {
				name = console.readLine();
				if ("exit".equals(name)) {
					System.exit(0);
				}
				client.send(name);
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
	// 注册所有server
	public static void initServer() {
		listServer.clear();
		// 从zk获取最新获取的注册服务连接
		final String memberServerPath = "/member";
		final ZkClient zkClient = new ZkClient("127.0.0.1:2181", 6000, 1000);
		// 获当前下子节点
		List<String> children = zkClient.getChildren(memberServerPath);
		listServer.clear();
		for (String p : children) {
			// 读取子节点value值
			listServer.add((String) zkClient.readData(memberServerPath + "/" + p));
		}
		System.out.println("最新服务信息listServer:" + listServer.toString());
		// 订阅子节点事件
		zkClient.subscribeChildChanges(memberServerPath, new IZkChildListener() {
			// 子节点发生变化
			public void handleChildChange(String parentPath, List<String> childrens) throws Exception {
				listServer.clear();
				for (String subP : childrens) {
					// 读取子节点value值
					listServer.add((String) zkClient.readData(memberServerPath + "/" + subP));
				}
			}
		});
	}
	// 服务调用次数
	private static int count = 1;
	// 会员服务集群数量，实际开发中不要写死，
	private static int memberServerCount = 2;
	// 获取当前server信息
	public static String getServer() {
		String serverName = listServer.get(count % memberServerCount);
		++count;
		return serverName;
	}
	public void send(String name) {
		String server = ZkServerClient.getServer();
		String[] cfg = server.split(":");
		Socket socket = null;
		BufferedReader in = null;
		PrintWriter out = null;
		try {
			socket = new Socket(cfg[0], Integer.parseInt(cfg[1]));
			in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
			out = new PrintWriter(socket.getOutputStream(), true);
			out.println(name);
			while (true) {
				String resp = in.readLine();
				if (resp == null)
					break;
				else if (resp.length() > 0) {
					System.out.println("Receive : " + resp);
					break;
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (out != null) {
				out.close();
			}
			if (in != null) {
				try {
					in.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			if (socket != null) {
				try {
					socket.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
	}
}

解析：当我们运行ZkServerScoekt.java后，再运行ZkServerClient.java,在ZkServerClient.java里面有一个main方法，接下来说执行流程：

 

 

 这是client.send方法的定义

 接下来我们来看服务器端的代码分析：

 

 

 运行效果截图：
这是zkServerClient控制台：

 这是18081服务器控制台：

这是18080服务器控制台： 

从以上结果可以看出，实现了负载均衡的轮询机制

常见负载均衡算法：轮询、权重、IP绑定