zookeeper 通知机制

import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;

public class ZooKeeperWatcherExample {
    public static void main(String[] args) throws Exception {
        // 连接到 ZooKeeper 服务器
        ZooKeeper zk = new ZooKeeper("localhost:2181", 3000, event -> {
            // 会话事件处理
            System.out.println("Session event: " + event.getState());
        });

        // 设置观察者
        String path = "/app1/config";
        zk.exists(path, new Watcher() {
            @Override
            public void process(WatchedEvent event) {
                System.out.println("Event type: " + event.getType());
                if (event.getType() == Event.EventType.NodeDataChanged) {
                    try {
                        // 重新设置观察者
                        zk.exists(path, this);
                        byte[] data = zk.getData(path, false, null);
                        System.out.println("New data: " + new String(data));
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }
        });

        // 保持程序运行，以便接收通知
        Thread.sleep(Long.MAX_VALUE);

        // 关闭连接
        zk.close();
    }
}