Zookeeper API for JAVA实战与应用

package com.zookeeper.watcher;

import java.util.List;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.atomic.AtomicInteger;

import org.apache.log4j.Logger;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.Watcher.Event.EventType;
import org.apache.zookeeper.Watcher.Event.KeeperState;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.ACL;
import org.apache.zookeeper.data.Stat;

public class ZKClient implements Watcher{
    private static final Logger logger = Logger.getLogger(ZKClient.class);
    
    //定义session失效时间
    private static final int SESSION_TIMEOUT = 10000;
    //zookeeper服务器地址
    private static final String ZOOKEEPER_ADDRESS = "192.168.56.1:2181";
    
    //ZooKeeper变量 
    private ZooKeeper zk = null;
    //定义原子变量
    AtomicInteger seq = new AtomicInteger();
    //信号量设置，用于等待zookeeper连接建立之后，通知阻塞程序继续向下执行
    private CountDownLatch connectedSemaphore = new CountDownLatch(1);
    
    public static void main(String[] args) throws InterruptedException {
        String parentPath= "/test"; //父节点
        String childrenPath = "/test/children"; //子节点
        
        ZKClient test = new ZKClient();
        //创建链接
        test.createConnection();
 
        boolean isSuccess = test.createNode(parentPath, "abc", Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
        if (isSuccess) {
            //读取数据
            String result = test.getNodeData(parentPath, true);
            logger.info("更新前数据：" + result);
            
            //更新数据
            isSuccess = test.updateNode(parentPath, String.valueOf(System.currentTimeMillis()));
            if(isSuccess){
                logger.info("更新后数据：" + test.getNodeData(parentPath, true));
            }
            
            // 创建子节点
            isSuccess = test.createNode(childrenPath, String.valueOf(System.currentTimeMillis()), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
            if(isSuccess){
                test.updateNode(childrenPath, String.valueOf(System.currentTimeMillis()));
            }
            
            //读取子节点
            List<String> childrenList = test.getChildren(parentPath, true);
            if(childrenList!=null && !childrenList.isEmpty()){
                for(String children : childrenList){
                    System.out.println("子节点：" + children);
                }
            }
        }
        
        Thread.sleep(1000);
        //创建临时有序子节点
       test.createNode(childrenPath, String.valueOf(System.currentTimeMillis()), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT_SEQUENTIAL);
       test.createNode(childrenPath, String.valueOf(System.currentTimeMillis()), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT_SEQUENTIAL);
       test.createNode(childrenPath, String.valueOf(System.currentTimeMillis()), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT_SEQUENTIAL);
        
        // 读取子节点，并删除
        List<String> childrenList = test.getChildren(parentPath, true);
        if (childrenList != null && !childrenList.isEmpty()) {
            for (String children : childrenList) {
                System.out.println("子节点：" + children);
                test.deleteNode(parentPath + "/" + children);
            }
        }

        //删除父节点 
        if (test.exists(childrenPath, false) != null) {
            test.deleteNode(childrenPath);
        }
        
        //释放链接
        Thread.sleep(1000);
        test.releaseConnection();
    }
    
 
    
    /**
     * 创建节点
     * 
     * @param path 节点路径
     * @param data 数据内容
     * @param acl 访问控制列表
     * @param createMode znode创建类型
     * @return
     */
    public boolean createNode(String path, String data, List<ACL> acl, CreateMode createMode) {
        try {
            //设置监控(由于zookeeper的监控都是一次性的，所以每次必须设置监控)
            exists(path, true);
            String resultPath = this.zk.create(path, data.getBytes(), acl, createMode);
            logger.info(String.format("节点创建成功，path: %s，data: %s", resultPath, data));
        } catch (Exception e) {
            logger.error("节点创建失败", e);
            return false;
        }
        
        return true;
    }
    
    /**
     * 更新指定节点数据内容
     * 
     * @param path 节点路径
     * @param data 数据内容
     * @return
     */
    public boolean updateNode(String path, String data) {
        try {
            Stat stat = this.zk.setData(path, data.getBytes(), -1);
            logger.info("更新节点数据成功，path：" + path + ", stat: " + stat);
        } catch (Exception e) {
            logger.error("更新节点数据失败", e);
            return false;
        }
        
        return true;
    }
    
    /**
     * 删除指定节点
     * 
     * @param path
     *            节点path
     */
    public void deleteNode(String path) {
        try {
            this.zk.delete(path, -1);
            logger.info("删除节点成功，path：" + path);
        } catch (Exception e) {
            logger.error("删除节点失败", e);
        }
    }
    

    
    /**
     * 读取节点数据
     * 
     * @param path 节点路径
     * @param needWatch 是否监控这个目录节点，这里的 watcher是在创建ZooKeeper实例时指定的watcher
     * @return
     */
    public String getNodeData(String path, boolean needWatch) {
        try {
            Stat stat = exists(path, needWatch);
            if(stat != null){
                return new String(this.zk.getData(path, needWatch, stat));
            }
        } catch (Exception e) {
            logger.error("读取节点数据内容失败", e);
        }
        
        return null;
    }
    
    /**
     * 获取子节点
     * 
     * @param path 节点路径
     * @param needWatch  是否监控这个目录节点，这里的 watcher是在创建ZooKeeper实例时指定的watcher
     * @return
     */
    public List<String> getChildren(String path, boolean needWatch) {
        try {
            return this.zk.getChildren(path, needWatch);
        } catch (Exception e) {
            logger.error("获取子节点失败", e);
            return null;
        }
    }
    
    
    /**
     * 判断znode节点是否存在
     * 
     * @param path 节点路径
     * @param needWatch 是否监控这个目录节点，这里的 watcher是在创建ZooKeeper实例时指定的watcher
     * @return
     */
    public Stat exists(String path, boolean needWatch) {
        try {
            return this.zk.exists(path, needWatch);
        } catch (Exception e) {
            logger.error("判断znode节点是否存在发生异常", e);
        }
        
        return null;
    }
    
    /**
     * 创建ZK连接
     * 
     * @param connectAddr
     * @param sessionTimeout
     */
    public void createConnection() {
        this.releaseConnection();
        
        try {
            zk = new ZooKeeper(ZOOKEEPER_ADDRESS, SESSION_TIMEOUT, this);
            logger.info("开始连接ZK服务器...");
            
            //zk连接未创建成功进行阻塞
            connectedSemaphore.await();
        } catch (Exception e) {
            logger.error("ZK连接创建失败", e);
        }
    }
    
    /**
     * 关闭ZK连接
     */
    public void releaseConnection() {
        if (this.zk != null) {
            try {
                this.zk.close();
                logger.info("ZK连接关闭成功");
            } catch (InterruptedException e) {
                logger.error("ZK连接关闭失败", e);
            }
        }
    }
    
    @Override
    public void process(WatchedEvent event) {
        logger.info("进入process()方法...event = " + event);
        
        if (event == null) {
            return;
        }
        
        KeeperState keeperState = event.getState(); // 连接状态
        EventType eventType = event.getType(); // 事件类型
        String path = event.getPath(); // 受影响的path
        
        String logPrefix = "【Watcher-" + this.seq.incrementAndGet() + "】";
        logger.info(String.format("%s收到Watcher通知...", logPrefix));
        logger.info(String.format("%s连接状态：%s", logPrefix, keeperState));
        logger.info(String.format("%s事件类型：%s", logPrefix, eventType));
        logger.info(String.format("%s受影响的path：%s", logPrefix, path));
        
        if (KeeperState.SyncConnected == keeperState) {
            if (EventType.None == eventType) {
                // 成功连接上ZK服务器
                logger.info(logPrefix + "成功连接上ZK服务器...");
                connectedSemaphore.countDown();
                
            } else if (EventType.NodeCreated == eventType) {
                // 创建节点
                logger.info(logPrefix + "节点创建");
                this.exists(path, true);
                 
            } else if (EventType.NodeDataChanged == eventType) {
                // 更新节点
                logger.info(logPrefix + "节点数据更新");
                logger.info(logPrefix + "数据内容: " + this.getNodeData(path, true));
                
            } else if (EventType.NodeChildrenChanged == eventType) {
                // 更新子节点
                logger.info(logPrefix + "子节点变更");
                logger.info(logPrefix + "子节点列表：" + this.getChildren(path, true));
            
            } else if (EventType.NodeDeleted == eventType) {
                // 删除节点
                logger.info(logPrefix + "节点 " + path + " 被删除");
            }
             
        } else if (KeeperState.Disconnected == keeperState) {
            logger.info(logPrefix + "与ZK服务器断开连接");
        } else if (KeeperState.AuthFailed == keeperState) {
            logger.info(logPrefix + "权限检查失败");
        } else if (KeeperState.Expired == keeperState) {
            logger.info(logPrefix + "会话失效");
        }
        
    }
    
}