Linux -- 基于zookeeper的java api(二)

Linux -- 基于zookeeper的java api(二)

写一个关于基于集群的zookeeper的自定义实现HA

基于客户端和监控器：使用监控的方法查看每个注册过的节点的状态来做出操作。

Watch：监控端

package com.huhu.zookeeper;

import java.util.concurrent.CountDownLatch;

import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;

public class AUTIManager {

	// zk对象
	static ZooKeeper zk;
	// 线程类 用来组织程序运行
	static CountDownLatch cdl = new CountDownLatch(1);
	String connection = "hu-hadoop1:2181,hu-hadoop2:2181,hu-hadoop3:2181";
	int TIMEOUT = 2000;

	// 监视器
	Watcher connectionWatch = new Watcher() {
		@Override
		public void process(WatchedEvent event) {
			// TODO Auto-generated method stub
			System.out.println("zk服務通知--------------------" + event.toString());
		}
	};

	// 监视器
	Watcher existsWath = new Watcher() {
		@Override
		public void process(WatchedEvent event) {
			// TODO Auto-generated method stub
			if (event.getType().toString().equals("None")) {
				System.out.println("none");
			} else if (event.getType().toString().equals("NodeCreated")) {
				System.out.println(event.getPath() + "节点上线");
			} else if (event.getType().toString().equals("NodeDeleted")) {
				System.out.println(event.getPath() + "节点下线");
			} else if (event.getType().toString().equals("NodeDataChanged")) {
				System.out.println(event.getPath() + "节点数据已经被修改");
			} else if (event.getType().toString().equals("NodeChildrenChanged")) {
				System.out.println(event.getPath() + "节点的子节点数据已经被修改");
			} else {
				System.out.println(event.toString());
			}

			// 重复注册 watch 事件是一次性消费
			try {
				zk.exists("/1708a1/node1", existsWath);
				zk.exists("/1708a1/node2", existsWath);
				zk.exists("/1708a1/node3", existsWath);
			} catch (Exception e) {
				// TODO: handle exception
				e.printStackTrace();
			}
		}
	};

	// 初始化
	public void init() {
		try {
			zk = new ZooKeeper(connection, TIMEOUT, connectionWatch);
		} catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
		}
	}

	// 将节点 /1708a1/node增加一个监听器
	public void Lookexit() {
		try {
			zk.exists("/1708a1/node1", existsWath);
			zk.exists("/1708a1/node2", existsWath);
			zk.exists("/1708a1/node3", existsWath);
		} catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
		}
	}

	public static void main(String[] args) throws Exception {
		AUTIManager m = new AUTIManager();
		m.init();
		m.Lookexit();
		cdl.await();

	}
}

client1：

package com.huhu.zookeeper;

import java.util.concurrent.CountDownLatch;

import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.Stat;

public class Client1 {

	static CountDownLatch cdl = new CountDownLatch(1);
	static String connection = "hu-hadoop1:2181,hu-hadoop2:2181,hu-hadoop3:2181";
	static int TIMEOUT = 2000;
	static ZooKeeper zk;

	static Watcher watcher = new Watcher() {
		@Override
		public void process(WatchedEvent event) {
			// TODO Auto-generated method stub
			System.out.println("接受到zk服務信息，会话连接完成");
			System.out.println("zk为：" + zk);
			try {
				Stat s = zk.exists("/1708a1", true);
				if (s == null) {
					System.out.println("节点不存在，创建节点");
					zk.create("/1708a1", "123".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
					System.out.println("/1708al/注册成并创建节点");
					zk.create("/1708a1/node1", "123".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
					System.out.println("创建node1 OK!!");
				} else {
					zk.create("/1708a1/node1", "123".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
					System.out.println("創建node1 OK!!");
				}
			} catch (Exception e) {
				// TODO: handle exception
				e.printStackTrace();
			}
		}
	};

	public static void main(String[] args) throws Exception {
		System.out.println("客戶2");
		zk = new ZooKeeper(connection, TIMEOUT, watcher);
		System.out.println("zk对象：" + zk);
		cdl.await();
	}
}

client2：

package com.huhu.zookeeper;

import java.util.concurrent.CountDownLatch;

import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.Stat;

public class Client2 {

	static CountDownLatch cdl = new CountDownLatch(1);
	static String connection = "hu-hadoop1:2181,hu-hadoop2:2181,hu-hadoop3:2181";
	static int TIMEOUT = 2000;
	static ZooKeeper zk;

	static Watcher watcher = new Watcher() {
		@Override
		public void process(WatchedEvent event) {
			// TODO Auto-generated method stub
			System.out.println("接受到zk服務信息，会话连接完成");
			System.out.println("zk为：" + zk);
			try {
				Stat s = zk.exists("/1708a1", true);
				if (s == null) {
					System.out.println("节点不存在，创建节点");
					zk.create("/1708a1", "123".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
					System.out.println("/1708a1注册成并创建节点");
					zk.create("/1708a1/node2", "123".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
					System.out.println("创建node2 OK!!");
				} else {
					zk.create("/1708a1/node2", "123".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
					System.out.println("創建node2 OK!!");
				}
			} catch (Exception e) {
				// TODO: handle exception
				e.printStackTrace();
			}
		}
	};

	public static void main(String[] args) throws Exception {
		System.out.println("客戶2");
		zk = new ZooKeeper(connection, TIMEOUT, watcher);
		System.out.println("zk对象：" + zk);
		cdl.await();
	}
}

client3：

package com.huhu.zookeeper;

import java.util.concurrent.CountDownLatch;

import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.Stat;

public class Client3 {

	static CountDownLatch cdl = new CountDownLatch(1);
	static String connection = "hu-hadoop1:2181,hu-hadoop2:2181,hu-hadoop3:2181";
	static int TIMEOUT = 2000;
	static ZooKeeper zk;

	static Watcher watcher = new Watcher() {
		@Override
		public void process(WatchedEvent event) {
			// TODO Auto-generated method stub
			System.out.println("接受到zk服務信息，会话连接完成");
			System.out.println("zk为：" + zk);
			try {
				Stat s = zk.exists("/1708a1", true);
				if (s == null) {
					System.out.println("节点不存在，创建节点");
					zk.create("/1708a1", "123".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
					System.out.println("/1708al/注册成并创建节点");
					zk.create("/1708a1/node3", "123".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
					System.out.println("创建node3 OK!!");
				} else {
					zk.create("/1708a1/node3", "123".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
					System.out.println("創建node3 OK!!");
				}
			} catch (Exception e) {
				// TODO: handle exception
				e.printStackTrace();
			}
		}
	};

	public static void main(String[] args) throws Exception {
		System.out.println("客戶3");
		zk = new ZooKeeper(connection, TIMEOUT, watcher);
		System.out.println("zk对象：" + zk);
		cdl.await();
	}
}

启动监控端：

将集群中没有/1708a1

启动3个client：

然后分别让他们下线：(停掉服务)

效果很明显。

谈谈mysql和zookeeper：

我自己瞎扯扯淡。。。

mysql和zookeeper都是用来存在数据的，但是存储方式优点不同，那点是MySQL是用表来存储的，zookeeper是按照数的结构存储的，但是zookeeper解决了MySQL的一个从始至终都没有解决的方法。就是并发问题，这就是zookeeper的优势zookeeper使用搭建集群的方式来解决并发问题(这里说的有点绝对)。

MySQL中的主从机制，写只能写入主中，而zookeeper中不存在，你写哪里都可以，并且它实时的和主同步数据，使从和主之间的数据同步。

MySQL由于有并发问题，这里的并发主要表现在读和写之间的问题，从而引出了线程问题(原子性，可见性，有序性)（隔离级别），从而有了rabbitmq和solr，这些解决方案，减少数据库的读，让它可以更准确的写和读。而zookeeper则也可以当作一个监控者或者大黑板，降低业务间的耦合度，解决了并发问题

这里不一定是正确的，是我自己对它们之间的感觉