Zookeeper : create,list,update zknodes using java

Interaction with zookeeper using java code

package com.rajkrrsingh.zk;

import java.io.IOException;
import java.util.List;
import java.util.concurrent.CountDownLatch;

import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooDefs;
import org.apache.zookeeper.ZooKeeper;

public class ZookeeperRecipe {
	
	private ZooKeeper zk=null;
	
	public ZooKeeper connnect(String hosts,int timeOut) throws IOException, InterruptedException{
		final CountDownLatch connectedSignal = new CountDownLatch(1);
		this.zk = new ZooKeeper(hosts,timeOut,new Watcher(){

			@Override
			public void process(WatchedEvent event) {
				if(event.getState() == Watcher.Event.KeeperState.SyncConnected){
					connectedSignal.countDown();
				}
				
			}
			
		});
		System.out.println("Before connectedSignal.await();");
		connectedSignal.await();
		System.out.println("after connectedSignal.await();");
		return zk;
	}
	
	public void createGroup(String groupName) throws KeeperException, InterruptedException{
		String path ="/"+groupName;
		zk.create(path, null /* data */, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
	}
	
	public void creatingGroupMembersWithData(String groupName,String member,byte[] data) throws Exception{
		String path="/"+groupName+"/"+member+"-"; // this will be sq
		
		System.out.println("created child node with path "+zk.create(path, data, ZooDefs.Ids.OPEN_ACL_UNSAFE,CreateMode.EPHEMERAL_SEQUENTIAL));
	}
	
	public void list(String zknode) throws Exception{
		String path="/"+zknode;
		List<String> children = zk.getChildren(path, new Watcher(){

			@Override
			public void process(WatchedEvent event) {
				if(event.getType()==Event.EventType.NodeChildrenChanged){
					System.out.println("node children updated");
				}
			}});
		
		if(children.isEmpty()){
			System.out.println("no children in the zknode");
			return;
		}
		System.out.println("Childrens : "+children+" : "+children.size());
	}
	
	private void delete(String zknode) throws Exception {
		String path ="/"+zknode;
		List<String> childNodes = zk.getChildren(path, false);
		//remove the childNodes first
		for(String childNode : childNodes){
			zk.delete(path+"/"+childNode, -1);
		}
		zk.delete(path, -1);
		System.out.println("Done deleting");
	}
	
	public static void main(String[] args) throws Exception{
		ZookeeperRecipe zkr = new ZookeeperRecipe();
			zkr.connnect("hostname:5181", 5000);
			System.out.println("Connected");
			System.out.println("Going to Create zk group");
			zkr.createGroup("demo-group");
			System.out.println("Creating group member zknodes with data");
			zkr.creatingGroupMembersWithData("demo-group", "childnode", "data1".getBytes());
			System.out.println("Created child node in the group");
			System.out.println("listing zknode --> childrens");
			zkr.list("demo-group");
			System.out.println("Deleting a zknode");
			zkr.delete("demo-group");
		
	}

	
}