zookeeper

package pfs.y2017.m11.zookeeper.demo04;

import java.util.Collections;
import java.util.List;
import java.util.Random;

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.ZooDefs.Ids;
import org.apache.zookeeper.ZooKeeper;

public class DistributedClientLock {
    

    // 会话超时
    private static final int SESSION_TIMEOUT = 2000;
    // zookeeper集群地址
    private String hosts = "192.168.1.192:2181,192.168.1.55:2181,192.168.1.28:2181";
    private String groupNode = "locks";
    private String subNode = "sub";
    private boolean haveLock = false;

    private ZooKeeper zk;
    // 记录自己创建的子节点路径
    private volatile String thisPath;

    /**
     * 连接zookeeper
     */
    public void connectZookeeper() throws Exception {
        zk = new ZooKeeper(hosts, SESSION_TIMEOUT, new Watcher() {
            public void process(WatchedEvent event) {
                try {

                    // 判断事件类型，此处只处理子节点变化事件
                    if (event.getType() == EventType.NodeChildrenChanged && event.getPath().equals("/" + groupNode)) {
                        //获取子节点，并对父节点进行监听
                        List<String> childrenNodes = zk.getChildren("/" + groupNode, true);
                        String thisNode = thisPath.substring(("/" + groupNode + "/").length());
                        // 去比较是否自己是最小id
                        Collections.sort(childrenNodes);
                        if (childrenNodes.indexOf(thisNode) == 0) {
                            //访问共享资源处理业务，并且在处理完成之后删除锁
                            doSomething();
                            
                            //重新注册一把新的锁
                            thisPath = zk.create("/" + groupNode + "/" + subNode, null, Ids.OPEN_ACL_UNSAFE,
                                    CreateMode.EPHEMERAL_SEQUENTIAL);
                        }
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });

        // 1、程序一进来就先注册一把锁到zk上
        thisPath = zk.create("/" + groupNode + "/" + subNode, null, Ids.OPEN_ACL_UNSAFE,
                CreateMode.EPHEMERAL_SEQUENTIAL);

        // wait一小会，便于观察
        Thread.sleep(new Random().nextInt(1000));

        // 从zk的锁父目录下，获取所有子节点，并且注册对父节点的监听
        List<String> childrenNodes = zk.getChildren("/" + groupNode, true);

        //如果争抢资源的程序就只有自己，则可以直接去访问共享资源 
        if (childrenNodes.size() == 1) {
            doSomething();
            thisPath = zk.create("/" + groupNode + "/" + subNode, null, Ids.OPEN_ACL_UNSAFE,
                    CreateMode.EPHEMERAL_SEQUENTIAL);
        }
    }

    /**
     * 处理业务逻辑，并且在最后释放锁
     */
    private void doSomething() throws Exception {
        try {
            System.out.println("gain lock: " + thisPath);
            Thread.sleep(2000);
            // do something
        } finally {
            System.out.println("finished: " + thisPath);
            // 锟斤拷thisPath删锟斤拷, 锟斤拷锟斤拷thisPath锟斤拷client锟斤拷锟斤拷锟酵ㄖ�
            // 锟洁当锟斤拷锟酵凤拷锟斤拷
            zk.delete(this.thisPath, -1);
        }
    }

    public static void main(String[] args) throws Exception {
        DistributedClientLock dl = new DistributedClientLock();
        dl.connectZookeeper();
        Thread.sleep(Long.MAX_VALUE);
    }

    
}

package pfs.y2017.m11.zookeeper.demo04;
import java.util.Collections;import java.util.List;import java.util.Random;
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.ZooDefs.Ids;import org.apache.zookeeper.ZooKeeper;
public class DistributedClientLock {
// 会话超时private static final int SESSION_TIMEOUT = 2000;// zookeeper集群地址private String hosts = "192.168.1.192:2181,192.168.1.55:2181,192.168.1.28:2181";private String groupNode = "locks";private String subNode = "sub";private boolean haveLock = false;
private ZooKeeper zk;// 记录自己创建的子节点路径private volatile String thisPath;
/** * 连接zookeeper */public void connectZookeeper() throws Exception {zk = new ZooKeeper(hosts, SESSION_TIMEOUT, new Watcher() {public void process(WatchedEvent event) {try {
// 判断事件类型，此处只处理子节点变化事件if (event.getType() == EventType.NodeChildrenChanged && event.getPath().equals("/" + groupNode)) {//获取子节点，并对父节点进行监听List<String> childrenNodes = zk.getChildren("/" + groupNode, true);String thisNode = thisPath.substring(("/" + groupNode + "/").length());// 去比较是否自己是最小idCollections.sort(childrenNodes);if (childrenNodes.indexOf(thisNode) == 0) {//访问共享资源处理业务，并且在处理完成之后删除锁doSomething();//重新注册一把新的锁thisPath = zk.create("/" + groupNode + "/" + subNode, null, Ids.OPEN_ACL_UNSAFE,CreateMode.EPHEMERAL_SEQUENTIAL);}}} catch (Exception e) {e.printStackTrace();}}});
// 1、程序一进来就先注册一把锁到zk上thisPath = zk.create("/" + groupNode + "/" + subNode, null, Ids.OPEN_ACL_UNSAFE,CreateMode.EPHEMERAL_SEQUENTIAL);
// wait一小会，便于观察Thread.sleep(new Random().nextInt(1000));
// 从zk的锁父目录下，获取所有子节点，并且注册对父节点的监听List<String> childrenNodes = zk.getChildren("/" + groupNode, true);
//如果争抢资源的程序就只有自己，则可以直接去访问共享资源 if (childrenNodes.size() == 1) {doSomething();thisPath = zk.create("/" + groupNode + "/" + subNode, null, Ids.OPEN_ACL_UNSAFE,CreateMode.EPHEMERAL_SEQUENTIAL);}}
/** * 处理业务逻辑，并且在最后释放锁 */private void doSomething() throws Exception {try {System.out.println("gain lock: " + thisPath);Thread.sleep(2000);// do something} finally {System.out.println("finished: " + thisPath);// 锟斤拷thisPath删锟斤拷, 锟斤拷锟斤拷thisPath锟斤拷client锟斤拷锟斤拷锟酵ㄖ�// 锟洁当锟斤拷锟酵凤拷锟斤拷zk.delete(this.thisPath, -1);}}
public static void main(String[] args) throws Exception {DistributedClientLock dl = new DistributedClientLock();dl.connectZookeeper();Thread.sleep(Long.MAX_VALUE);}
}