2021最新zookeeper系列

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Ⅰ：zookeeper的單機安裝 - 詳細教程：https://blog.csdn.net/Kevinnsm/article/details/116134397?spm=1001.2014.3001.5501

Ⅱ：zookeeper的相關shell命令：https://blog.csdn.net/Kevinnsm/article/details/116137602?spm=1001.2014.3001.5501

Ⅲ：zookeeper之查看節點的狀態信息：https://blog.csdn.net/Kevinnsm/article/details/116143218?spm=1001.2014.3001.5501

Ⅳ：zookeeper的acl權限控制：https://blog.csdn.net/Kevinnsm/article/details/116167394?spm=1001.2014.3001.5501

Ⅴ：zookeeper的相關Java Api：https://blog.csdn.net/Kevinnsm/article/details/116462557?spm=1001.2014.3001.5501

Ⅵ：zookeeper的Watcher事件監聽機制：https://blog.csdn.net/Kevinnsm/article/details/116501842?spm=1001.2014.3001.5501

Ⅶ：教你一招利用zookeeper作為服務的配置中心：https://blog.csdn.net/Kevinnsm/article/details/116542974?spm=1001.2014.3001.5501

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文章目錄

• 前置：--》把握住Watcher流程《--
• 一、環境搭建
• • Ⅰ、使用工具
  • Ⅱ、創建節點
  • Ⅲ、代碼編寫

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前置：–》把握住Watcher流程《–

1、連接zookeeper服務器
2、連接時必須使當前線程等待（等待其他線程創建連接zookeeper服務成功，使用計數器實現）
3、執行回調函數process
4、釋放當前線程

一、環境搭建

演示mysql的連接配置（將mysql連接屬性配置到zookeeper服務器）

Ⅰ、使用工具

使用云服務器作為zookeeper的演示環境，本地使用xshell遠程連接
如果不知，請移步：https://blog.csdn.net/Kevinnsm/article/details/116134397?spm=1001.2014.3001.5501

Ⅱ、創建節點

create /config “config”
create /config/mysql “datasource”
create /config/mysql/driver "com.mysql.cj.jdbc.Driver
create /config/mysql/url "jdbc:mysql://127.0.0.1/test?serverTimezone=UTC
create /config/mysql/username “root”
create /config/mysql/password “xxxxxxx”

Ⅲ、代碼編寫

package com.zookeeper.config;import com.zookeeper.watcher.WatcherConnection; import org.apache.zookeeper.KeeperException; import org.apache.zookeeper.WatchedEvent; import org.apache.zookeeper.Watcher; import org.apache.zookeeper.ZooKeeper; import org.junit.Test;import java.io.IOException; import java.util.concurrent.CountDownLatch;/*** @author:抱著魚睡覺的喵喵* @date:2021/5/8* @description:*/ public class ZookeeperConfigCenter implements Watcher { //mysql的本地變量private String driver;private String url;private String username;private String password;static ZooKeeper zooKeeper;static CountDownLatch countDownLatch = new CountDownLatch(1);final static String IP = "8.140.37.103:2181"; //構造函數，只要一創建該類，就執行getProperty()方法public ZookeeperConfigCenter() {getProperty();}//重寫回調函數@Overridepublic void process(WatchedEvent watchedEvent) {try {if (watchedEvent.getType() == Event.EventType.None) {if (watchedEvent.getState() == Event.KeeperState.SyncConnected) {System.out.println("連接成功");//如果連接成功，放行當前線程countDownLatch.countDown();} else if (watchedEvent.getState() == Event.KeeperState.Disconnected) {System.out.println("連接中斷");} else if (watchedEvent.getState() == Event.KeeperState.Expired) {System.out.println("連接超時");//如果連接超時就重新進行連接zooKeeper = new ZooKeeper(IP, 5000, new WatcherConnection());} else if (watchedEvent.getState() == Event.KeeperState.AuthFailed) {System.out.println("驗證失敗");}//如果監聽到節點數據發生了變化，就重新連接讀取節點數據} else if (watchedEvent.getType() == Event.EventType.NodeDataChanged) {getProperty();}} catch (IOException e) {e.printStackTrace();}} //核心方法public void getProperty() {try {//連接zookeeper服務zooKeeper = new ZooKeeper(IP, 20000, this);//等待其他線程連接zookeeper服務countDownLatch.await();this.driver = new String(zooKeeper.getData("/config/mysql/driver", true, null));this.url = new String(zooKeeper.getData("/config/mysql/url", true, null));this.username = new String(zooKeeper.getData("/config/mysql/username", true, null));this.password = new String(zooKeeper.getData("/config/mysql/password", true, null));} catch (IOException e) {e.printStackTrace();} catch (InterruptedException e) {e.printStackTrace();} catch (KeeperException e) {e.printStackTrace();}}@Testpublic void test() {try {ZookeeperConfigCenter configCenter = new ZookeeperConfigCenter();for (int i = 1; i < 6; i++) {System.out.println(configCenter.driver);System.out.println(configCenter.url);System.out.println(configCenter.username);System.out.println(configCenter.password);//休眠10秒Thread.sleep(10000);}} catch (Exception e) {e.printStackTrace();}} }

另外也用到了一個簡單的連接類作為zookeeper連接超時的回調處，然后進性重新連接（實現了watcher接口）

public class WatcherConnection implements Watcher {static CountDownLatch countDownLatch = new CountDownLatch(1);//計數器static ZooKeeper zooKeeper;public static void main(String[] args) {try {zooKeeper = new ZooKeeper("123.57.252.59:2181", 5000, new WatcherConnection());countDownLatch.await();Thread.sleep(10000);zooKeeper.close();} catch (IOException e) {e.printStackTrace();} catch (InterruptedException e) {e.printStackTrace();}}@Overridepublic void process(WatchedEvent watchedEvent) {try {if (watchedEvent.getType() == Event.EventType.None) {if (watchedEvent.getState() == Event.KeeperState.SyncConnected) {System.out.println("連接成功!");countDownLatch.countDown();} else if (watchedEvent.getState() == Event.KeeperState.Disconnected) {System.out.println("斷開連接");} else if (watchedEvent.getState() == Event.KeeperState.Expired) {System.out.println("超時了");} else if (watchedEvent.getState() == Event.KeeperState.AuthFailed) {System.out.println("認證失敗!");}}} catch (Exception e) {e.printStackTrace();}}}

測試

可以看出當監聽到/config/mysql/username節點的數據發生變更時，控制臺就會重新獲取節點值

如果控制臺出現了ConnectionLoss錯誤，可能是網絡差導致連接斷開或者服務器宕機

總結

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