Zookeeper 监听服务器节点动态上下线（代码复制即可用）

￡神魔★判官ぃ 2022-12-28 09:11 155阅读 0赞

### 文章目录 ###

*   *  需求
     *  思路
     *  实现步骤
     *  创建两个自定义类
     *   *  自定义DistrbuteServer（服务器端代码块）
         *  自定义 DistributeClient（客户端代码）
     *  测试
     *   *  客户端查看测试
         *  server 节点查看测试

## 需求 ##

某分布式系统中，主节点可以有多台，可以动态上下线，任意一台客户端都能实时感知到主节点服务器的上下线。  
思路

## 思路 ##

1. 创建客户端与服务端
       2.启动client端 监听
       3. 启动server端 注册
       4.当server端 发生上下线
       5.client端都能感知到

## 实现步骤 ##

1.在shell命令客户端创建 servers (方便连接)

create /servers "servers"

![在这里插入图片描述][20201216112224638.png]

## 创建两个自定义类 ##

![在这里插入图片描述][20201216111935998.png]

### 自定义DistrbuteServer（服务器端代码块） ###

package com.zookeeper.servers;
    
    import org.apache.xerces.dom.ParentNode;
    import org.apache.zookeeper.*;
    
    import java.io.IOException;
    import java.util.Scanner;
    
    /** * @version v1.0 * @Author: huang* * @Date: 2020/12/16* */
    public class DistrbuteServer { 
        private static String connectString="bigdata01:2181,bigdata02:2181,bigdata03:2181";
        private static int sessionTimeout=2000;
        private ZooKeeper zk=null;
        private String partentNode ="/servers";
    
        //创建zk的客户端连接
        public  void getConnect() throws IOException { 
             zk = new ZooKeeper(connectString, sessionTimeout, new Watcher() { 
                @Override
                public void process(WatchedEvent watchedEvent) { 
                    if (watchedEvent.getState() == Event.KeeperState.SyncConnected) { 
                        System.out.println("servers端连接成功");
                    }
                }
            });
        }
    
         //注册服务器（创建一个临时序列节点）
        //
        public void registServer(String hostname) throws Exception{ 
            String create = zk.create(partentNode + "/server", hostname.getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);
            System.out.println(hostname+"is online"+ create);
        }
    
       //业务功能
        public void business(String hostname) throws Exception{ 
            System.out.println(hostname+"is working,,,,");
                //保证线程不结束
               Thread.sleep(Long.MAX_VALUE);
        }
    
        public static void main(String[] args) throws Exception { 
            System.out.println("请输入服务器的名字");
            String hostname = new Scanner(System.in).next();
    
             //1.获取zk连接
            DistrbuteServer server = new DistrbuteServer();
            server.getConnect();
             //2.利用zk连接注册服务器信息
            server.registServer(hostname);
            //3.启动业务功能
            server.business(hostname);
    
        }
    
    }

### 自定义 DistributeClient（客户端代码） ###

package com.zookeeper.servers;
    
    
    import org.apache.hadoop.classification.InterfaceAudience;
    import org.apache.hadoop.ipc.Client;
    import org.apache.hadoop.mapreduce.tools.CLI;
    import org.apache.zookeeper.KeeperException;
    import org.apache.zookeeper.WatchedEvent;
    import org.apache.zookeeper.Watcher;
    import org.apache.zookeeper.ZooKeeper;
    
    import java.util.ArrayList;
    import java.util.List;
    
    /** * @version v1.0 * @Author: huang* * @Date: 2020/12/16* */
    public class DistributeClient { 
        private  static String connectString="bigdata01:2181,bigdata02:2181,bigdata03:2181";
        private static  int sessionTimeout=20000;
        private ZooKeeper zk=null;
        private String parentNode="/servers";
    
        //创建zk客户端连接
        public  void getConnect()throws Exception{ 
            zk=new ZooKeeper(connectString, sessionTimeout, new Watcher() { 
                @Override
                public void process(WatchedEvent watchedEvent) { 
                    if (watchedEvent.getState()==Event.KeeperState.SyncConnected) { 
                        System.out.println("client 客户端连接成功!");
                    }
                        //再一次启动监听
                        try { 
                            getServerList();
                        } catch (Exception e) { 
                            e.printStackTrace();
                        }
                    }
    
            });
        }
    
         //获取服务器列表信息
        public  void getServerList() throws KeeperException, InterruptedException { 
            //1.获取服务器节点信息，并且对父节点进行监听
            List<String> children = zk.getChildren(parentNode, true);
             //2.存储服务器信息列表
            ArrayList<String> servers = new ArrayList<>();
            //3.遍历所有节点，获取节点中的主机名称信息
            for (String child : children) { 
                byte[] data = zk.getData(parentNode + "/" + child, false, null);
                servers.add(new String(data));
                //4.打印服务器列表信息
                System.out.println(servers);
    
            }
    
            //业务功能
    
    
    
    
    
        }
    
        public void business() throws InterruptedException { 
            System.out.println("client is working,,,");
            Thread.sleep(Long.MAX_VALUE);
        }
    
        public static void main(String[] args) throws Exception { 
            DistributeClient client
                    = new DistributeClient();
            client.getConnect();
            client.getServerList();
            client.business();
        }
    
    }

## 测试 ##

shell命令行创建节点  
![在这里插入图片描述][20201216112634889.png]

### 客户端查看测试 ###

![在这里插入图片描述][20201216112704791.png]

### server 节点查看测试 ###

![在这里插入图片描述][20201216112755591.png]  
![在这里插入图片描述][20201216112745669.png]

[20201216112224638.png]: /images/20221120/83e23dd650194a3485ceda718528bef9.png
[20201216111935998.png]: /images/20221120/d9f24c6c91e64cbfbd05a38d5376abbb.png
[20201216112634889.png]: /images/20221120/b57f4c3e0a6a43468f15c2e72c9cc1ea.png
[20201216112704791.png]: /images/20221120/f70a85d502fa4b83b71674b40adc2d95.png
[20201216112755591.png]: /images/20221120/4b5d13a4435846e4a612af46f081b142.png
[20201216112745669.png]: /images/20221120/25ef36efef1d4558a30787c57086451b.png