zookeeper在集群管理中的应用-优快云博客

本文链接：https://blog.youkuaiyun.com/MrTangShunHai/article/details/84428268

在我们的下载平台中，为了提高下载速度，我们使用了集群，为了管理集群中服务器的状态，我们使用了zookeeper，在集群中，集群管理器维护server列表，新增server,删除server时，能及时通知集群管理器，集群如下图所示

[img]http://dl.iteye.com/upload/attachment/0084/1584/71e04a78-19e5-3012-92fc-82a1d1f408e3.jpg[/img]

一环境搭建

先下载zookeeper-3.3.5，解压，修改conf目录下的zoo配置文件

tickTime=2000
initLimit=10
syncLimit=5
dataDir=F:/zookeeperserver1/zookeeper-3.3.5/data
clientPort=2181
dataLogDir=F:/zookeeperserver1/zookeeper-3.3.5/datalog
server.1=127.0.0.1:2888:3888
server.2=127.0.0.1:2889:3889
server.3=127.0.0.1:2890:3890

启动bin目录下的zkServer

二开发测试

1 创建集群管理器createmaster类，createmaster类主要负责在zookeeper上创建主节点,并监听主节点下的子节点，代码如下



public class CreateMaster implements Watcher {

	//zookeeper客户端连接实例
	private ZooKeeper zk;

	private CountDownLatch connectSingn=new CountDownLatch(1);

	public void connect(String host) throws InterruptedException
	{
		try {
			zk=new ZooKeeper(host,5000,this);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		connectSingn.await();

	}

	public void createmaster(String mastername) throws KeeperException, InterruptedException
	{
		String path="/"+mastername;

		//创建父节点
		String createpath=zk.create(path, null, Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);

		//监听子节点
		ServerListWatch serverlistwatch=new ServerListWatch(zk);

		zk.getChildren("/"+mastername, serverlistwatch);

		System.out.println("createpath="+createpath); 
	}




	public void close() throws InterruptedException
	{
		zk.close();
	}

	@Override
	public void process(WatchedEvent event) {
		// TODO Auto-generated method stub
		if(event.getState() == KeeperState.SyncConnected) 
		 {
		  System.out.println("已经触发了" + event.getType() + "事件！");
		  connectSingn.countDown();
		 }

	}

	/**
	 * @param args
	 * @throws InterruptedException 
	 */
	public static void main(String[] args) throws InterruptedException {
		// TODO Auto-generated method stub

		CreateMaster createmaster=new CreateMaster();

		createmaster.connect("localhost:2181");


		try {

			//创建父节点
			createmaster.createmaster("serverlist");
		} catch (KeeperException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		Thread.sleep(600000);

		try {
			createmaster.close();
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}



	}

}

2 创建服务节点createserver类,服务节点类主要负责在zookeeper中创建临时的子节点

代码如下



public class CreateServer implements Watcher {

	//zookeeper客户端连接实例
	private ZooKeeper zk;

	private CountDownLatch connectSingn=new CountDownLatch(1);

	public void connect(String host) throws InterruptedException
	{
		try {
			zk=new ZooKeeper(host,5000,this);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		connectSingn.await();


	}

	public void createserver(String mastername,String servername) throws KeeperException, InterruptedException
	{



		String path="/"+mastername+"/"+servername;

		String createpath=zk.create(path, null, Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);



		System.out.println("createpath="+createpath); 
	}

	public void close() throws InterruptedException
	{

		zk.close();
	}
	@Override
	public void process(WatchedEvent event) {
		// TODO Auto-generated method stub
		 if(event.getState() == KeeperState.SyncConnected) 
		 {
		  System.out.println("已经触发了" + event.getType() + "事件！");
		  connectSingn.countDown();
		 }



	}

	public static void main(String[] args) throws InterruptedException {

	    CreateServer createserver=new CreateServer();

		createserver.connect("localhost:2181");

		try {
			createserver.createserver("serverlist", "server1");
		} catch (KeeperException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		Thread.sleep(120000);

		createserver.close();
	}

}

3 创建监听子节点类serverlistwatch,监听子节点主要负责监听子节点，以及回调函数处理，代码如下


public class ServerListWatch implements Watcher {

	//zookeeper客户端连接实例
	private ZooKeeper zk;

	public 	ServerListWatch(ZooKeeper zk)
	{
		this.zk=zk;
    }

	public void connect(String host)
	{
		try {
			zk=new ZooKeeper(host,5000,this);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}


	}

	public void close() throws InterruptedException
	{

		zk.close();
	}

	@Override
	public void process(WatchedEvent event) {
		// TODO Auto-generated method stub

		if(event.getState() == KeeperState.SyncConnected) 
		{  
			System.out.println("已经触发了" + event.getType() + "事件！");


		}

		    if(event.getType() == EventType.NodeChildrenChanged) 
			{
				System.out.println("children change"); 

				ListServer listserver=new ListServer(zk);



				try {
					//打印子节点
					listserver.list("serverlist");
				} catch (KeeperException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}

				try {

					ServerListWatch serverlistwatch=new ServerListWatch(zk);

					//重新监听
					listserver.addchildremwatch("serverlist",serverlistwatch);

				} catch (KeeperException e1) {
					// TODO Auto-generated catch block
					e1.printStackTrace();
				} catch (InterruptedException e1) {
					// TODO Auto-generated catch block
					e1.printStackTrace();
				}


			}

	}

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub

	}

}

4 创建打印服务器信息listserver类,主要负责打印服务器集群信息，代码如下



public class ListServer implements Watcher{

	//zookeeper客户端连接实例
	private ZooKeeper zk;

	private CountDownLatch connectSingn=new CountDownLatch(1);

	public ListServer(ZooKeeper zk)
	{
		this.zk=zk;
	}

	public void connect(String host) throws InterruptedException
	{
		try {
			zk=new ZooKeeper(host,5000,this);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		connectSingn.await();

	}

	public void list(String master) throws KeeperException, InterruptedException
	{
		String path="/"+master;

		List<String> children=zk.getChildren(path, false);

		if(children!=null&&children.size()>0)
		{
			for(String child: children)
			{
				System.out.println("children="+child); 
			}
		}
		else
		{
			System.out.println("no children"); 
		}


	}

	public void addchildremwatch(String master,ServerListWatch serverlistwatch) throws KeeperException, InterruptedException
	{
		String path="/"+master;

		//ServerListWatch serverlistwatch=new ServerListWatch();

		zk.getChildren(path, serverlistwatch);
	}

	public void close() throws InterruptedException
	{

		zk.close();
	}

	@Override
	public void process(WatchedEvent event) {
		// TODO Auto-generated method stub
		 if(event.getState() == KeeperState.SyncConnected) 
		 {
		  System.out.println("已经触发了" + event.getType() + "事件！");
		  connectSingn.countDown();
		 }



	}
	/**
	 * @param args
	 * @throws InterruptedException 
	 * @throws KeeperException 
	 */
	public static void main(String[] args) throws KeeperException, InterruptedException {
		// TODO Auto-generated method stub

		ListServer listserver=new ListServer(null);

		listserver.connect("localhost:2181");

		listserver.list("serverlist");

		listserver.close();
	}

}

5 测试代码，结果如下

已经触发了None事件！
createpath=/serverlist
已经触发了NodeChildrenChanged事件！
children change
children=server1
已经触发了NodeChildrenChanged事件！
children change
children=server1
children=server2
已经触发了NodeChildrenChanged事件！
children change
children=server1
已经触发了NodeChildrenChanged事件！
children change
no children

从测试中可以清楚的看到服务节点的新增和删除。