zookeeper實現廣播

zookeeper實現廣播

一、簡介

很多時候會遇到這樣的場景：一個消息或者通知需要通知給所有集羣中所有的節點，這些節點收到通知後執行一定邏輯。

使用方不得持續高頻（一分鐘大於10次）投遞通知

使用方不得投遞體積過大的數據，不得大於512KB

使用方不得濫用資源

二、安裝zookeeper

啓動命令

bin/zookeeper-server-start.sh config/zookeeper.properties

三、Maven依賴

<dependency>
    <groupId>org.apache.curator</groupId>
    <artifactId>curator-framework</artifactId>
    <version>2.9.0</version>
</dependency>
<dependency>
    <groupId>org.apache.curator</groupId>
    <artifactId>curator-client</artifactId>
    <version>2.9.0</version>
</dependency>
<dependency>
    <groupId>org.apache.curator</groupId>
    <artifactId>curator-recipes</artifactId>
    <version>2.9.0</version>
</dependency>
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.1.35</version>
</dependency>

四、監聽客戶端代碼

package zookeeper;

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.recipes.cache.NodeCache;
import org.apache.curator.framework.recipes.cache.NodeCacheListener;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.apache.curator.utils.ZKPaths;
import org.apache.zookeeper.ZooKeeper;

import java.nio.charset.Charset;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * Created by zhengyong on 16/11/24.
 */
public class Listener {

    private static final int sessionTimeout = 15000;
    private static final String ZK_HOST = "127.0.0.1:2181";
    private static final String ZK_PATH = "/zkPath";

    private static ExecutorService executorService = Executors.newFixedThreadPool(5);

    public static void main(String[] args) throws Exception {

        // 創建node
        ZooKeeper zookeeper = new ZooKeeper(ZK_HOST, sessionTimeout, null);
        ZKPaths.mkdirs(zookeeper, ZK_PATH);

        // 創建5個listener
        for (int i = 0; i < 5; i++) {
            final int index = i + 1;
            executorService.execute(new Runnable() {

                @Override
                public void run() {
                    try {
                        createListeners("Thread-" + index);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            });
        }
        // 模擬程序運行不中斷
        Thread.sleep(100000);
        executorService.shutdown();
    }

    /**
     * 創建listener
     *
     * @param threadName 線程名稱
     * @throws Exception
     */
    private static void createListeners(final String threadName) throws Exception {
        CuratorFramework localCuratorClient = CuratorFrameworkFactory.builder().connectString(ZK_HOST).sessionTimeoutMs(sessionTimeout).retryPolicy(new ExponentialBackoffRetry(1000,
                10, 5000)).build();
        localCuratorClient.start();

        final NodeCache nodeCache = new NodeCache(localCuratorClient, ZK_PATH);
        nodeCache.getListenable().addListener(new NodeCacheListener() {

            @Override
            public void nodeChanged() throws Exception {
                final byte[] curr = nodeCache.getCurrentData().getData();// 取到最新的數據

                System.out.println(String.format("%s收到客戶端通知: %s", threadName, new String(curr, Charset.forName("UTF-8"))));
                // 業務邏輯
            }
        });
        // 一定要start()
        nodeCache.start();
        System.out.println(String.format("listener %s start", threadName));

        // 系統關閉的時候請調用nodeCache.close();
    }

}

五、通知客戶端代碼

package zookeeper;

import com.alibaba.fastjson.JSON;
import com.google.common.collect.Maps;
import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.utils.ZKPaths;
import org.apache.zookeeper.ZooKeeper;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.apache.zookeeper.data.Stat;

import java.nio.charset.Charset;
import java.util.Map;

/**
 * Created by zhengyong on 16/11/24.
 */
public class Notify {

    private static final int    sessionTimeout = 15000;
    private static final String ZK_HOST        = "1127.0.0.1:2181";
    private static final String ZK_PATH        = "/zkPath";

    public static void main(String[] args) throws Exception {

        // 創建node
        ZooKeeper zookeeper = new ZooKeeper(ZK_HOST, sessionTimeout, null);
        ZKPaths.mkdirs(zookeeper, ZK_PATH);

        CuratorFramework localCuratorClient = CuratorFrameworkFactory.builder().connectString(ZK_HOST) 
                                                                     .sessionTimeoutMs(sessionTimeout).retryPolicy(new ExponentialBackoffRetry(1000,
                                                                                                                                               10,
                                                                                                                                               5000)).build();
        localCuratorClient.start();

        final Map<String, Object> data = Maps.newHashMap();
        data.put("version", System.currentTimeMillis());
        data.put("data", "我想刪除第一條數據");// 放入業務數據

        final Stat stat = new Stat();
        final byte[] oldData = localCuratorClient.getData().storingStatIn(stat).forPath(ZK_PATH); // 先讀區舊數據
        System.out.println(String.format("oldData: %s ", new String(oldData, Charset.forName("UTF-8"))));
        System.out.println(String.format("newData: %s", JSON.toJSONString(data)));

        // 若不需要處理舊數據就直接往下
        byte[] newData = JSON.toJSONString(data).getBytes(Charset.forName("UTF-8"));
        // 防止併發問題
        final Stat newStat = localCuratorClient.setData().withVersion(stat.getVersion()).forPath(ZK_PATH, newData);
        System.out.println(String.format("write data result :%s", JSON.toJSONString(newStat)));

        // 模擬程序運行不中斷
        Thread.sleep(100000);
    }

}