zookeeper节点监视Watcher

本是古典何须时尚 2024-04-17 05:47 56阅读 0赞

import org.apache.zookeeper.*;
    
    import java.util.List;
    
    public class Main {
        public static void main(String[] args) {
            //初始化log4j，zookeeper否则报错。
            org.apache.log4j.BasicConfigurator.configure();
    
            try {
                Main m = new Main("");
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    
        public Main(String arg){
            try {
                test();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    
        private ZooKeeper mZooKeeper;
    
        private void test() throws Exception{
            String ip = "localhost";
            String addrs = ip + ":2181," + ip + ":2182," + ip + ":2183";
    
            //连接zookeeper服务器。
            //addrs是一批地址，如果其中某一个服务器挂掉，其他仍可用。
            mZooKeeper = new ZooKeeper(addrs, 300 * 1000, new MyWatcher());
    
            synchronized (Main.class) {
                System.out.println("处理...");
                Main.class.wait();
            }
        }
    
        private class MyWatcher implements Watcher {
            @Override
            public void process(WatchedEvent event) {
                byte[] data =null;
                try {
                    data = mZooKeeper.getData("/test_data", true, null);
                } catch (Exception e) {
                    e.printStackTrace();
                }
    
                System.out.println("类型:" + event.getType());
                System.out.println("路径:" + event.getPath());
                if(data!=null)
                System.out.println("数据修改:" + new String(data));
    
                if (mZooKeeper.getState() == ZooKeeper.States.CONNECTED) {
                    System.out.println("状态:ZooKeeper.States.CONNECTED");
                }
    
                if (event.getState() == Event.KeeperState.SyncConnected) {
                    System.out.println("状态:Event.KeeperState.SyncConnected");
                }
            }
        }
    }

此时，若在监听的节点/test\_data通过set命令更新数据：

![20190823202011402.png][]

Java程序代码输出：

类型:NodeDataChanged
    路径:/test_data
    数据修改:hello.world!
    状态:ZooKeeper.States.CONNECTED

[20190823202011402.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/11/810d88b680ad4379a8a5355af8a56704.png