zookeeper sample code

standalone.java

	private void runZk() throws IOException, InterruptedException {
  		int numConnections = 5000;
		int tickTime = 2000;
		String dataDirectory = System.getProperty("java.io.tmpdir");
		File dir = new File(dataDirectory, "zookeeper").getAbsoluteFile();
		ZooKeeperServer server = new ZooKeeperServer(dir, dir, tickTime);
		NIOServerCnxn.Factory standaloneServerFactory = new NIOServerCnxn.Factory(new InetSocketAddress(clientPort), numConnections);
		standaloneServerFactory.startup(server);
	}

ZkStateShareHelper.java

import java.io.IOException;

import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.ZooDefs;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.Stat;

import com.taobao.top.push.Client;

public class ZkStateShareHelper {
  public static String zkConnectString;
	public static String zkRootPath;

	private static ZooKeeper zk;
	private static Stat prevStat;

	public static void init(String zkConnectString, String zkRootPath) {
		try {
			zk = new ZooKeeper(zkConnectString, 600000, null);
		} catch (IOException e) {
			e.printStackTrace();
			return;
		}
	}

	public static void shareState(Client client, String backend) {
		try {
			String path = getPath(client);
			Stat stat = zk.exists(path, false);
			if (stat == null) {
				zk.create(path,
						backend.getBytes(),
						ZooDefs.Ids.OPEN_ACL_UNSAFE,
						CreateMode.EPHEMERAL);
				prevStat = zk.exists(path, false);
			} else if (prevStat == null || prevStat.getVersion() != stat.getVersion()) {
				prevStat = stat;
				zk.setData(path, backend.getBytes(), stat.getVersion());
			}
		} catch (KeeperException e) {
			e.printStackTrace();
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
	}

	private static String getPath(Client client) {
		return zkRootPath + "/" + client.getId();
	}
}

ZookeeperTest.java

import java.io.File;
import java.net.InetSocketAddress;

import static org.junit.Assert.*;

import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.ZooDefs;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.Stat;
import org.apache.zookeeper.server.NIOServerCnxn;
import org.apache.zookeeper.server.ZooKeeperServer;
import org.junit.Test;

public class ZookeeperTest {
  @Test
	public void create_get_test() throws Exception {
		// zk server
		int clientPort = 21818;
		int numConnections = 5000;
		int tickTime = 2000;
		String dataDirectory = System.getProperty("java.io.tmpdir");
		File dir = new File(dataDirectory, "zookeeper").getAbsoluteFile();
		ZooKeeperServer server = new ZooKeeperServer(dir, dir, tickTime);
		NIOServerCnxn.Factory standaloneServerFactory = new NIOServerCnxn.Factory(new InetSocketAddress(clientPort), numConnections);
		standaloneServerFactory.startup(server);

		ZooKeeper zk1 = new ZooKeeper("127.0.0.1:" + clientPort, 30000, null);
		ZooKeeper zk2 = new ZooKeeper("127.0.0.1:" + clientPort, 30000, null);

		try {
			String path = "/clientId";
			String ip = "10.13.3.1";
			zk1.create(path, ip.getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
			assertEquals(ip, new String(zk1.getData(path, null, null)));

			// zk1 first set it
			String ipChange = "10.13.3.2";
			Stat stat = zk1.exists(path, true);
			assertEquals(0, stat.getVersion());
			zk1.setData(path, ipChange.getBytes(), stat.getVersion());
			// version
			assertEquals(1, zk1.exists(path, true).getVersion());
			assertEquals(1, zk2.exists(path, true).getVersion());
			// data
			assertEquals(ipChange, new String(zk1.getData(path, null, null)));
			assertEquals(ipChange, new String(zk2.getData(path, null, null)));

			// zk2 change it, version plus 1
			ipChange = "10.13.3.3";
			stat = zk2.exists(path, true);
			assertEquals(1, stat.getVersion());
			zk2.setData(path, ipChange.getBytes(), stat.getVersion());
			// version
			assertEquals(2, zk1.exists(path, true).getVersion());
			assertEquals(2, zk2.exists(path, true).getVersion());
			// data
			assertEquals(ipChange, new String(zk1.getData(path, null, null)));
			assertEquals(ipChange, new String(zk2.getData(path, null, null)));

			// zk1 change it again
			ipChange = "10.13.3.4";
			stat = zk1.exists(path, true);
			assertEquals(2, stat.getVersion());
			zk1.setData(path, ipChange.getBytes(), stat.getVersion());
			// version
			assertEquals(3, zk1.exists(path, true).getVersion());
			assertEquals(3, zk2.exists(path, true).getVersion());
			// data
			assertEquals(ipChange, new String(zk1.getData(path, null, null)));
			assertEquals(ipChange, new String(zk2.getData(path, null, null)));
		} catch (Exception e) {
			throw e;
		} finally {
			zk1.close();
		}
	}
}