ZooKeeper是一个分布式的,开放源码的分布式应用程序协调服务框架,包含一组简单的原语集合。通过这些原语言的组合使用,能够帮助我们解决更高层次的分布式问题,关于ZooKeeper的典型使用场景,请查看这个文章《ZooKeeper典型使用场景一览》
本文主要针对ZooKeeper提供的Java API,通过实际代码讲述如何使用API。
- package com.taobao.taokeeper.research.sample;
- import java.io.IOException;
- 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.Watcher.Event.KeeperState;
- import org.apache.zookeeper.ZooDefs.Ids;
- import org.apache.zookeeper.ZooKeeper;
- import common.toolkit.java.util.ObjectUtil;
- /**
- * ZooKeeper Java Api 使用样例<br>
- * ZK Api Version: 3.4.3
- *
- * @author nileader/nileader@gmail.com
- */
- public class JavaApiSample implements Watcher {
- private static final int SESSION_TIMEOUT = 10000;
- private static final String CONNECTION_STRING = "test.zookeeper.connection_string:2181";
- private static final String ZK_PATH = "/nileader";
- private ZooKeeper zk = null;
- private CountDownLatch connectedSemaphore = new CountDownLatch( 1 );
- /**
- * 创建ZK连接
- * @param connectString ZK服务器地址列表
- * @param sessionTimeout Session超时时间
- */
- public void createConnection( String connectString, int sessionTimeout ) {
- this.releaseConnection();
- try {
- zk = new ZooKeeper( connectString, sessionTimeout, this );
- connectedSemaphore.await();
- } catch ( InterruptedException e ) {
- System.out.println( "连接创建失败,发生 InterruptedException" );
- e.printStackTrace();
- } catch ( IOException e ) {
- System.out.println( "连接创建失败,发生 IOException" );
- e.printStackTrace();
- }
- }
- /**
- * 关闭ZK连接
- */
- public void releaseConnection() {
- if ( !ObjectUtil.isBlank( this.zk ) ) {
- try {
- this.zk.close();
- } catch ( InterruptedException e ) {
- // ignore
- e.printStackTrace();
- }
- }
- }
- /**
- * 创建节点
- * @param path 节点path
- * @param data 初始数据内容
- * @return
- */
- public boolean createPath( String path, String data ) {
- try {
- System.out.println( "节点创建成功, Path: "
- + this.zk.create( path, //
- data.getBytes(), //
- Ids.OPEN_ACL_UNSAFE, //
- CreateMode.EPHEMERAL )
- + ", content: " + data );
- } catch ( KeeperException e ) {
- System.out.println( "节点创建失败,发生KeeperException" );
- e.printStackTrace();
- } catch ( InterruptedException e ) {
- System.out.println( "节点创建失败,发生 InterruptedException" );
- e.printStackTrace();
- }
- return true;
- }
- /**
- * 读取指定节点数据内容
- * @param path 节点path
- * @return
- */
- public String readData( String path ) {
- try {
- System.out.println( "获取数据成功,path:" + path );
- return new String( this.zk.getData( path, false, null ) );
- } catch ( KeeperException e ) {
- System.out.println( "读取数据失败,发生KeeperException,path: " + path );
- e.printStackTrace();
- return "";
- } catch ( InterruptedException e ) {
- System.out.println( "读取数据失败,发生 InterruptedException,path: " + path );
- e.printStackTrace();
- return "";
- }
- }
- /**
- * 更新指定节点数据内容
- * @param path 节点path
- * @param data 数据内容
- * @return
- */
- public boolean writeData( String path, String data ) {
- try {
- System.out.println( "更新数据成功,path:" + path + ", stat: " +
- this.zk.setData( path, data.getBytes(), -1 ) );
- } catch ( KeeperException e ) {
- System.out.println( "更新数据失败,发生KeeperException,path: " + path );
- e.printStackTrace();
- } catch ( InterruptedException e ) {
- System.out.println( "更新数据失败,发生 InterruptedException,path: " + path );
- e.printStackTrace();
- }
- return false;
- }
- /**
- * 删除指定节点
- * @param path 节点path
- */
- public void deleteNode( String path ) {
- try {
- this.zk.delete( path, -1 );
- System.out.println( "删除节点成功,path:" + path );
- } catch ( KeeperException e ) {
- System.out.println( "删除节点失败,发生KeeperException,path: " + path );
- e.printStackTrace();
- } catch ( InterruptedException e ) {
- System.out.println( "删除节点失败,发生 InterruptedException,path: " + path );
- e.printStackTrace();
- }
- }
- public static void main( String[] args ) {
- JavaApiSample sample = new JavaApiSample();
- sample.createConnection( CONNECTION_STRING, SESSION_TIMEOUT );
- if ( sample.createPath( ZK_PATH, "我是节点初始内容" ) ) {
- System.out.println();
- System.out.println( "数据内容: " + sample.readData( ZK_PATH ) + "\n" );
- sample.writeData( ZK_PATH, "更新后的数据" );
- System.out.println( "数据内容: " + sample.readData( ZK_PATH ) + "\n" );
- sample.deleteNode( ZK_PATH );
- }
- sample.releaseConnection();
- }
- /**
- * 收到来自Server的Watcher通知后的处理。
- */
- @Override
- public void process( WatchedEvent event ) {
- System.out.println( "收到事件通知:" + event.getState() +"\n" );
- if ( KeeperState.SyncConnected == event.getState() ) {
- connectedSemaphore.countDown();
- }
- }
- }
输出结果:
- 收到事件通知:SyncConnected
- 节点创建成功, Path: /nileader, content: 我是节点初始内容
- 获取数据成功,path:/nileader
- 数据内容: 我是节点初始内容
- 更新数据成功,path:/nileader, stat: 42950186407,42950186408,1350820182392,1350820182406,1,0,0,232029990722229433,18,0,42950186407
- 获取数据成功,path:/nileader
- 数据内容: 更新后的数据
- 删除节点成功,path:/nileader
本文转自 nileader 51CTO博客,原文链接:http://blog.51cto.com/nileader/795265,如需转载请自行联系原作者