Zookeeper Java API

续前话,Zookeeper的环境已经搭建好了.接下来就是利用Java实现与zookeeper的连接,达到和ZOOKEEPER_HOME\bin\zkCli.sh中的部分基础功能.

具体的zookeeper的安装见 ZooKeeper起步配置.

import java.io.IOException;
import java.util.concurrent.CountDownLatch;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.Watcher.Event.KeeperState;

/**
 * @author ruodao
 * @since 1.0
 * 2010-2-18 下午08:57:36
 */
public class AbstractZooKeeper implements Watcher {
	private static final int SESSION_TIME 	= 2000;
	protected ZooKeeper  zooKeeper;
	protected CountDownLatch countDownLatch	= new CountDownLatch(1);

	public void connect(String hosts) throws IOException, InterruptedException{
		zooKeeper = new ZooKeeper(hosts,SESSION_TIME,this);
		countDownLatch.await();
	}
	public void process(WatchedEvent event) {
		if(event.getState() == KeeperState.SyncConnected){
			countDownLatch.countDown();
		}
	}
	public void close() throws InterruptedException{
		zooKeeper.close();
	}
}

下面一段代码实现了简单的操作,添加,获取数据,获取子节点.

import java.util.Arrays;
import java.util.List;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.ZooDefs.Ids;

/**
 * @author ruodao
 * @since 1.0
 * 2010-2-18 下午09:03:21
 */
public class ZooKeeperOperator extends AbstractZooKeeper {
	/**
	 * 创建持久态的znode,比支持多层创建.比如在创建/parent/child的情况下,无/parent.无法通过.
	 * @param path eg:  /parent/child1
	 * @param data
	 * @throws InterruptedException 
	 * @throws KeeperException 
	 */
	public void create(String path,byte[] data) throws KeeperException, InterruptedException{
		this.zooKeeper.create(path, data, Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT/*此处创建的为持久态的节点,可为瞬态*/);
	}
	
	
	/**
	 * 获取节点的孩子信息
	 * @param path
	 * @throws KeeperException
	 * @throws InterruptedException
	 */
	public void getChild(String path) throws KeeperException, InterruptedException{
		try {
			List<String> children = this.zooKeeper.getChildren(path, false);
			if (children.isEmpty()) {
				System.out.printf("没有节点在%s中.", path);
				return;
			}else{
				System.out.printf("节点%s中存在的节点:\n", path);
				for(String child: children){
					System.out.println(child);
				}
			}
		} catch (KeeperException.NoNodeException e) {
			System.out.printf("%s节点不存在.", path);
			throw e;
		}
	}

	public byte[] getData(String path) throws KeeperException, InterruptedException {
		return	this.zooKeeper.getData(path, false,null);
	}
}

main函数

public static void main(String[] args) {
		try {
			ZooKeeperOperator zkoperator			 = new ZooKeeperOperator();
			zkoperator.connect("192.168.0.115");
			byte[] data = new byte[]{'d','a','t','a'};
			
			zkoperator.create("/root",null);
			System.out.println(Arrays.toString(zkoperator.getData("/root")));
			
			zkoperator.create("/root/child1",data);
			System.out.println(Arrays.toString(zkoperator.getData("/root/child1")));
			
			zkoperator.create("/root/child2",data);
			System.out.println(Arrays.toString(zkoperator.getData("/root/child2")));
			
			System.out.println("节点孩子信息:");
			zkoperator.getChild("/root");
			
			zkoperator.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

到这里,一个简单的程序已经可以运行了.以下是linux上的截图.