Zookeeper学习笔记4

开源客户端

ZkClient

        <dependency>
            <groupId>org.apache.zookeeper</groupId>
            <artifactId>zookeeper</artifactId>
            <version>3.4.10</version>
        </dependency>

package com.xh.zk.zkclient;

import org.I0Itec.zkclient.IZkDataListener;
import org.I0Itec.zkclient.ZkClient;

/**
 * Created by root on 4/3/18.
 */
public class ZkClientTest {
    static String conllection = "192.168.2.192:2181";
    static ZkClient zkClient;

    public static void main(String[] args) throws InterruptedException {
        zkClient = new ZkClient(conllection, 5000);
        zkClient.readData("/aaa");
        zkClient.readData("/aaa/bbb");
        zkClient.subscribeDataChanges("/aaa", new IZkDataListener() {
            public void handleDataChange(String s, Object o) throws Exception {
                System.out.println("handleDataChange>>>" + s + ":" + o);
            }

            public void handleDataDeleted(String s) throws Exception {
                System.out.println("handleDataDeleted>>>" + s);
            }
        });

        zkClient.subscribeDataChanges("/aaa/bbb", new IZkDataListener() {
            public void handleDataChange(String s, Object o) throws Exception {
                System.out.println("handleDataChange>>>" + s + ":" + o);
            }

            public void handleDataDeleted(String s) throws Exception {
                System.out.println("handleDataDeleted>>>" + s);
            }
        });

        zkClient.createPersistent("/aaa/bbb", true);
        zkClient.writeData("/aaa", "hello");
        zkClient.writeData("/aaa/bbb", "ssss");
        zkClient.deleteRecursive("/aaa");
        Thread.sleep(Integer.MAX_VALUE);
    }
}

结果：

handleDataChange>>>/aaa:hello
handleDataChange>>>/aaa/bbb:ssss
handleDataDeleted>>>/aaa/bbb
handleDataDeleted>>>/aaa

Curato

创建客户端

        <dependency>
            <groupId>org.apache.curator</groupId>
            <artifactId>curator-framework</artifactId>
            <version>4.0.0</version>
        </dependency>

public class ZkCurator {

    public static void main(String[] args) throws InterruptedException {
        String connectStr = "192.168.2.192:2181";
        int sessionTimeOut = 5000;
        int connectTimeOut = 5000;
        RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);
        CuratorFramework client = CuratorFrameworkFactory.newClient(connectStr, sessionTimeOut,
                connectTimeOut, retryPolicy);

        CuratorFramework client2 = CuratorFrameworkFactory.builder().connectString(connectStr)
                .sessionTimeoutMs(sessionTimeOut).connectionTimeoutMs(connectTimeOut)
                .retryPolicy(retryPolicy).build();
        client.start();
        client2.start();

        Thread.sleep(Integer.MAX_VALUE);
    }

}

节点操作

        /**
         * C
         */
        client.create().creatingParentsIfNeeded().withMode(CreateMode.EPHEMERAL)
                .forPath(path, "init".getBytes());
        /**
         * R
         */
        Stat stat = new Stat();
        byte[] bytes = client.getData().storingStatIn(stat).forPath("/zk_book/hello");
        System.out.println(new String(bytes));
        /**
         * U
         */
        client.setData().withVersion(-1).forPath("/zk_book", "hi".getBytes());
        System.out.println(new String(client.getData().forPath("/zk_book")));
        /**
         * D
         */
        client.delete().deletingChildrenIfNeeded().withVersion(-1).forPath("/zk_book");

异步操作

    public static void main(String[] args) throws Exception {
        String connectStr = "192.168.2.192:2181";
        int sessionTimeOut = 5000;
        int connectTimeOut = 5000;
        String path = "/zk_book";
        final CountDownLatch semaphore = new CountDownLatch(2);
        ExecutorService tp = Executors.newFixedThreadPool(5);

        RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);
        CuratorFramework client = CuratorFrameworkFactory.builder().connectString(connectStr)
                .sessionTimeoutMs(sessionTimeOut).connectionTimeoutMs(connectTimeOut)
                .retryPolicy(retryPolicy).build();

        client.start();

        client.create().creatingParentsIfNeeded().withMode(CreateMode.EPHEMERAL)
                .inBackground(new BackgroundCallback() {
                    public void processResult(CuratorFramework curatorFramework, CuratorEvent curatorEvent) throws Exception {
                        System.out.println("event_code:" + curatorEvent.getResultCode() + "  event_type:" + curatorEvent.getType());
                        System.out.println("thread_result:" + Thread.currentThread().getName());
                        semaphore.countDown();
                    }
                }, tp).forPath(path, "init".getBytes());

        client.create().creatingParentsIfNeeded().withMode(CreateMode.EPHEMERAL)
                .inBackground(new BackgroundCallback() {
                    public void processResult(CuratorFramework curatorFramework, CuratorEvent curatorEvent) throws Exception {
                        System.out.println("event_code:" + curatorEvent.getResultCode() + "  event_type:" + curatorEvent.getType());
                        System.out.println("thread_result:" + Thread.currentThread().getName());
                        semaphore.countDown();
                    }
                }, tp).forPath(path, "init".getBytes());

        semaphore.await();
        tp.shutdown();

    }

结果：

event_code:0  event_type:CREATE
thread_result:pool-1-thread-1
event_code:-110  event_type:CREATE
thread_result:pool-1-thread-2

典型应用

        <dependency>
            <groupId>org.apache.curator</groupId>
            <artifactId>curator-recipes</artifactId>
            <version>4.0.0</version>
        </dependency>

事件监听

NodeCache

    public static void main(String[] args) throws Exception {
        String connectStr = "192.168.2.192:2181";
        int sessionTimeOut = 5000;
        int connectTimeOut = 5000;
        String path = "/zk_book";
        final CountDownLatch semaphore = new CountDownLatch(2);
        ExecutorService tp = Executors.newFixedThreadPool(5);

        RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);
        CuratorFramework client = CuratorFrameworkFactory.builder().connectString(connectStr)
                .sessionTimeoutMs(sessionTimeOut).connectionTimeoutMs(connectTimeOut)
                .retryPolicy(retryPolicy).build();

        client.start();

        final NodeCache nodeCache = new NodeCache(client, path, false);
        nodeCache.start(true);
        nodeCache.getListenable().addListener(new NodeCacheListener() {
            public void nodeChanged() throws Exception {
                System.out.println("data changed:" + new String(nodeCache.getCurrentData().getData()));
            }
        });

        client.create().creatingParentsIfNeeded().withMode(CreateMode.EPHEMERAL).forPath(path, "init".getBytes());
        client.setData().forPath(path, "update".getBytes());
        Thread.sleep(1000);
        client.delete().forPath(path);

        Thread.sleep(Integer.MAX_VALUE);

    }

结果：

data changed:init
data changed:update

其监听的结果在创建和修改时会通知，删除时不会

Mast选举

    public static void main(String[] args) throws Exception {
        String connectStr = "192.168.2.192:2181";
        int sessionTimeOut = 5000;
        int connectTimeOut = 5000;
        String master_path = "/zk_book";

        RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);
        CuratorFramework client = CuratorFrameworkFactory.builder().connectString(connectStr)
                .sessionTimeoutMs(sessionTimeOut).connectionTimeoutMs(connectTimeOut)
                .retryPolicy(retryPolicy).build();

        client.start();

        LeaderSelector selector = new LeaderSelector(client, master_path, new LeaderSelectorListenerAdapter() {
            public void takeLeadership(CuratorFramework curatorFramework) throws Exception {
                System.out.println("be Master");
                Thread.sleep(1000);
                System.out.println("give up be Master");
            }
        });

        selector.autoRequeue();
        selector.start();

        Thread.sleep(Integer.MAX_VALUE);

    }

分布式锁

一个订单号生成器的例子

1、没有锁：

    public static void main(String[] args) {
        final CountDownLatch semaphore = new CountDownLatch(1);

        for (int i = 0; i < 10; i++) {
            new Thread(new Runnable() {
                public void run() {
                    try {
                        semaphore.await();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }

                    SimpleDateFormat dateFormat = new SimpleDateFormat("HH:mm:ss|SSS");
                    String orderNo = dateFormat.format(new Date());
                    System.out.println("NO:" + orderNo);
                }
            }).start();
        }
        semaphore.countDown();
    }

结果：

NO:15:05:28|362
NO:15:05:28|364
NO:15:05:28|364
NO:15:05:28|363
NO:15:05:28|364
NO:15:05:28|365
NO:15:05:28|364
NO:15:05:28|365
NO:15:05:28|365
NO:15:05:28|365

2、zk分布式锁

public class ZkCurator {
    public static void main(String[] args) throws Exception {
        String connectStr = "192.168.2.192:2181";
        int sessionTimeOut = 5000;
        int connectTimeOut = 5000;
        String lock_path = "/zk_lock";

        RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);
        CuratorFramework client = CuratorFrameworkFactory.builder().connectString(connectStr)
                .sessionTimeoutMs(sessionTimeOut).connectionTimeoutMs(connectTimeOut)
                .retryPolicy(retryPolicy).build();
        client.start();

        final InterProcessMutex lock = new InterProcessMutex(client, lock_path);
        final CountDownLatch semaphoer = new CountDownLatch(1);

        for (int i = 0; i < 30; i++) {
            new Thread(new Runnable() {
                public void run() {
                    try {
                        semaphoer.await();
                        lock.acquire();
                        Thread.sleep(1000);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }

                    SimpleDateFormat dateFormat = new SimpleDateFormat("HH:mm:ss|SSS");
                    String orderNo = dateFormat.format(new Date());
                    System.out.println("NO:" + orderNo);
                    try {
                        lock.release();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }).start();
        }
        semaphoer.countDown();
    }

}

结果：

NO:15:26:49|695
NO:15:26:50|706
NO:15:26:51|715
NO:15:26:52|733
NO:15:26:53|753
...