Zookeeper实现负载均衡原理

╰+攻爆jí腚メ 2022-01-28 13:17 253阅读 0赞

# [Zookeeper实现负载均衡原理][Zookeeper] #

## 先玩个正常的，好玩的socket编程： ##

服务端：

首先公共的这个Handler：

package com.toov5.zkDubbo;
    
    import java.io.BufferedReader;
    import java.io.IOException;
    import java.io.InputStreamReader;
    import java.io.PrintWriter;
    import java.net.Socket;
    
    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;
                }
            }
        }
    }

package com.toov5.zkDubbo;
    
    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 static int port = 18080;  //socket 服务启动后的所使用的 端口号
    
        public static void main(String[] args) throws IOException {
            ZkServerScoekt server = new ZkServerScoekt(port);  //构造函数传入port
        //    regServer();  //去zk注册
            Thread thread = new Thread(server);
            thread.start();
        }
    
        public ZkServerScoekt(int port) {
            this.port = port;
        }
    //  //注册服务
    //    public static void regServer(){
    //        //1、建立zk连接
    //    ZkClient zkClient = new ZkClient("192.168.91.5",5000,10000);
    //        //2.先创建父节点
    //    String root = "/toov5";
    //    if (!zkClient.exists(root)) {
    //        //如果父节点不存，直接创建父节点
    //        zkClient.createPersistent(root);  //持久节点
    //    }
    //       //3、创建子节点
    //     String nodeName = root+"/service_"+port;      
    //     String nodeValue="127.0.0.1:"+port;
    //     if (zkClient.exists(nodeName)) {  //如果存在 直接删除掉
    //        zkClient.delete(nodeName);
    //    }
    //     zkClient.createEphemeral(nodeName); //字节的 临时节点  如果服务宕机了 找不到了就
    //     System.out.println("服务注册成功"+nodeName);
    //     
    //    }
    //    
    //    
        
        public void run() {
            ServerSocket serverSocket = null;
            try {
                serverSocket = new ServerSocket(port);
                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) {
    
                }
            }
        }
    
    }

客户端：

package com.toov5.zkDubbo;
    
    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;
    
    public class ZkServerClient {
        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();
            listServer.add("127.0.0.1:18080"); //连接服务 放到list中   存放集群地址 做负载均衡用的
        }
    
        // 获取当前server信息
        public static String getServer() {
            return listServer.get(0);
        }
        
        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();
                    }
                }
            }
        }
    }

运行结果：

![1179709-20181103002051183-439886477.png][]

## 引申思路 ##

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。

![1179709-20181102205858298-1781058.png][]

1、会员服务 项目启动时候 会在zk上面创建临时节点  /toov5 对应的value是127.0.0.1

如果是集群  /toov5 下面会会以 节点形式存储 节点名字就是IP+端口    value 分别也是 IP+端口   有些是没有用到value的哦

2、订单直接去使用 /toov5 查询下面的子节点信息，获取到之后。在本地使用负载均衡算法实现调用，决定使用哪个。

127.0.0.1:8080

127.0.0.1:8081

PS： 任何服务的底层都是 socke 技术

socket客户端 （ 客户端去获取注册信息）                                                          socket服务器端

废话不多说，项目：

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

这个不是Apache的哦注意

服务端代码：

package com.toov5.zkDubbo;
    
    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 static int port = 18081;  //socket 服务启动后的所使用的 端口号
    
        public static void main(String[] args) throws IOException {
            ZkServerScoekt server = new ZkServerScoekt(port);  //构造函数传入port
            regServer();  //去zk注册
            Thread thread = new Thread(server);
            thread.start();
        }
    
        public ZkServerScoekt(int port) {
            this.port = port;
        }
      //注册服务
        public static void regServer(){
            //1、建立zk连接
        ZkClient zkClient = new ZkClient("192.168.91.5",5000,10000);
            //2.先创建父节点
        String root = "/toov5";
        if (!zkClient.exists(root)) {
            //如果父节点不存，直接创建父节点
            zkClient.createPersistent(root);  //持久节点
        }
           //3、创建子节点
         String nodeName = root+"/service_"+port;      
         String nodeValue="127.0.0.1:"+port;
         if (zkClient.exists(nodeName)) {  //如果存在 直接删除掉
            zkClient.delete(nodeName);
        }
         zkClient.createEphemeral(nodeName); //字节的 临时节点  如果服务宕机了 找不到了就
         System.out.println("服务注册成功"+nodeName);
         
        }
        
        
        
        public void run() {
            ServerSocket serverSocket = null;
            try {
                serverSocket = new ServerSocket(port);
                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) {
    
                }
            }
        }
    
    }

客户端代码：

package com.toov5.zkDubbo;
    
    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;
    
    public class ZkServerClient {
        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();
            listServer.add("127.0.0.1:18080"); //连接服务 放到list中   存放集群地址 做负载均衡用的
        }
    
        // 获取当前server信息
        public static String getServer() {
            return listServer.get(0);
        }
        
        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();
                    }
                }
            }
        }
    }

![1179709-20181102233640889-670850507.png][]

启动服务端后的结果：

可以看到 去zk注册了信息。服务的名字 和子节点

其中子节点是 临时节点 相当于如果服务宕机了 就查不到了哦

![1179709-20181103000813179-1038410821.png][]

启动三次服务端后：

![1179709-20181103003633234-1677646649.png][]

然后 去zk读取节点信息：

客户端  **负载均衡轮训算法**

请求次数 %  服务端数 = 服务器端口号的奇数偶数

客户端：

package com.toov5.zkDubbo;
    
    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.ZkClient;
    
    public class ZkServerClient {
        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();
    //        listServer.add("127.0.0.1:18080"); //连接服务 放到list中   存放集群地址 做负载均衡用的   
            //建立zk连接
            ZkClient zkClient = new ZkClient("192.168.91.5",5000,10000);
            //读取父节点信息
            String root = "/toov5";
            List<String> children=zkClient.getChildren(root);
            for(String pString : children){
                //父+子 =完整的路径
                String path = root+"/"+pString;
                String nodeValue =zkClient.readData(path);
                //把值放到集合中去
                listServer.add(nodeValue);
            }
            //服务发现成功
             System.out.println("服务发现:"+listServer.toString());
             //然后给 serverCount赋值
             serverCount=listServer.size();
             
        }
     
      //请求总数
        private static  int  reqCount = 1;
      //服务个数    
        private static int  serverCount = 0; //初始值是0
        
        // 获取当前server信息
        public static String getServer() {
    //        return listServer.get(0);  不能写死  本地负载均衡轮询算法
        String serverName = listServer.get(reqCount%serverCount );
        System.out.println("客户端请求次数："+reqCount+"对应服务器"+serverName);
        reqCount++;
        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();
                    }
                }
            }
        }
    }

启动后（后端服务启动三个）：

![1179709-20181103010756253-4521993.png][]

访问一次：取模算法后的结果

![1179709-20181103010942606-1195397108.png][]

第二次、第三次：

![1179709-20181103011134065-448809196.png][]

看到结果 太美妙了！

美妙集中在此：

![1179709-20181103011310933-1708484618.png][]

好好欣赏下~~

[Zookeeper]: https://www.cnblogs.com/toov5/p/9899238.html
[1179709-20181103002051183-439886477.png]: /images/20220128/52dae3c6fc1546f8b3a9a8423af5e913.png
[1179709-20181102205858298-1781058.png]: /images/20220128/162b05aa78d54b23a44495c49f560510.png
[1179709-20181102233640889-670850507.png]: /images/20220128/46f2f371154e47dab96dab82e90d9ec2.png
[1179709-20181103000813179-1038410821.png]: /images/20220128/b62e724aaabd4ca6b096b60bf4d9f7a6.png
[1179709-20181103003633234-1677646649.png]: /images/20220128/564be4e19b7040d58f4ca2ef0fb0bf0d.png
[1179709-20181103010756253-4521993.png]: /images/20220128/fdb1726168d34ae094e29ce0a5a281fa.png
[1179709-20181103010942606-1195397108.png]: /images/20220128/3f6665dc5f7141539a495928e2b1f877.png
[1179709-20181103011134065-448809196.png]: /images/20220128/c49dce5c5f394f8782f69b0b9d364dbe.png
[1179709-20181103011310933-1708484618.png]: /images/20220128/26992ee4c4e24121a21effeb241322a4.png