Ⅶ：教你一招利用zookeeper作为服务的配置中心-CFANZ编程社区

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文章目录

前置：--》把握住Watcher流程《--
一、环境搭建

Ⅰ、使用工具
Ⅱ、创建节点
Ⅲ、代码编写

前置：–》把握住Watcher流程《–

1、连接zookeeper服务器
2、连接时必须使当前线程等待（等待其他线程创建连接zookeeper服务成功，使用计数器实现）
3、执行回调函数process
4、释放当前线程

一、环境搭建

演示mysql的连接配置（将mysql连接属性配置到zookeeper服务器）

Ⅰ、使用工具

使用云服务器作为zookeeper的演示环境，本地使用xshell远程连接如果不知，请移步

Ⅱ、创建节点

Ⅲ、代码编写

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:抱着鱼睡觉的喵喵
 * @date:2021/5/8
 * @description:
 */
public class ZookeeperConfigCenter implements Watcher {
//mysql的本地变量
    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";
//构造函数，只要一创建该类，就执行getProperty()方法
    public ZookeeperConfigCenter() {
        getProperty();
    }
    //重写回调函数
    @Override
    public void process(WatchedEvent watchedEvent) {
        try {
            if (watchedEvent.getType() == Event.EventType.None) {
                if (watchedEvent.getState() == Event.KeeperState.SyncConnected) {
                    System.out.println("连接成功");
                    //如果连接成功，放行当前线程
                    countDownLatch.countDown();
                } else if (watchedEvent.getState() == Event.KeeperState.Disconnected) {
                    System.out.println("连接中断");
                } else if (watchedEvent.getState() == Event.KeeperState.Expired) {
                    System.out.println("连接超时");
                    //如果连接超时就重新进行连接
                    zooKeeper = new ZooKeeper(IP, 5000, new WatcherConnection());
                } else if (watchedEvent.getState() == Event.KeeperState.AuthFailed) {
                    System.out.println("验证失败");
                }
                //如果监听到节点数据发生了变化，就重新连接读取节点数据
            } else if (watchedEvent.getType() == Event.EventType.NodeDataChanged) {
                getProperty();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
//核心方法
    public void getProperty() {
        try {
        //连接zookeeper服务
            zooKeeper = new ZooKeeper(IP, 20000, this);
            //等待其他线程连接zookeeper服务
            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();
        }
    }

    @Test
    public 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();
        }
    }
}

另外也用到了一个简单的连接类作为zookeeper连接超时的回调处，然后进性重新连接（实现了watcher接口）

public class WatcherConnection implements Watcher {
    static CountDownLatch countDownLatch = new CountDownLatch(1);
    //计数器
    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();
        }
    }
    @Override
    public void process(WatchedEvent watchedEvent) {
        try {
            if (watchedEvent.getType() == Event.EventType.None) {
                if (watchedEvent.getState() == Event.KeeperState.SyncConnected) {
                    System.out.println("连接成功!");
                    countDownLatch.countDown();
                } else if (watchedEvent.getState() == Event.KeeperState.Disconnected) {
                    System.out.println("断开连接");
                } else if (watchedEvent.getState() == Event.KeeperState.Expired) {
                    System.out.println("超时了");
                } else if (watchedEvent.getState() == Event.KeeperState.AuthFailed) {
                    System.out.println("认证失败!");
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}