zookeeper实现广播

r囧r小猫 2022-07-14 02:40 160阅读 0赞

## zookeeper实现广播 ##

#### 一、简介 ####

很多时候会遇到这样的场景：一个消息或者通知需要通知给所有集群中所有的节点，这些节点收到通知后执行一定逻辑。

> 使用方不得持续高频（一分钟大于10次）投递通知
> 
> 使用方不得投递体积过大的数据，不得大于512KB
> 
> 使用方不得滥用资源

#### 二、安装zookeeper ####

启动命令

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

#### 三、Maven依赖 ####

<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、监听客户端代码 ####

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 {
    
            // 创建node
            ZooKeeper zookeeper = new ZooKeeper(ZK_HOST, sessionTimeout, null);
            ZKPaths.mkdirs(zookeeper, ZK_PATH);
    
            // 创建5个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();
                        }
                    }
                });
            }
            // 模拟程序运行不中断
            Thread.sleep(100000);
            executorService.shutdown();
        }
    
        /** * 创建listener * * @param threadName 线程名称 * @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();// 取到最新的数据
    
                    System.out.println(String.format("%s收到客户端通知: %s", threadName, new String(curr, Charset.forName("UTF-8"))));
                    // 业务逻辑
                }
            });
            // 一定要start()
            nodeCache.start();
            System.out.println(String.format("listener %s start", threadName));
    
            // 系统关闭的时候请调用nodeCache.close();
        }
    
    }

#### 五、通知客户端代码 ####

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 {
    
            // 创建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", "我想删除第一条数据");// 放入业务数据
    
            final Stat stat = new Stat();
            final byte[] oldData = localCuratorClient.getData().storingStatIn(stat).forPath(ZK_PATH); // 先读区旧数据
            System.out.println(String.format("oldData: %s ", new String(oldData, Charset.forName("UTF-8"))));
            System.out.println(String.format("newData: %s", JSON.toJSONString(data)));
    
            // 若不需要处理旧数据就直接往下
            byte[] newData = JSON.toJSONString(data).getBytes(Charset.forName("UTF-8"));
            // 防止并发问题
            final Stat newStat = localCuratorClient.setData().withVersion(stat.getVersion()).forPath(ZK_PATH, newData);
            System.out.println(String.format("write data result :%s", JSON.toJSONString(newStat)));
    
            // 模拟程序运行不中断
            Thread.sleep(100000);
        }
    
    }