ZooKeeper

1.安装      https://www.cnblogs.com/mh-study/p/10368891.html

 

 https://blog.csdn.net/qiunian144084/article/details/79192819    windows下集群

https://www.cnblogs.com/mustone/p/7373671.html

import org.apache.zookeeper.*;
import org.apache.zookeeper.data.Stat;

import java.io.IOException;

public class Demo1 {
    private ZooKeeper zookeeper;
    private String oldValue = "";
    private String newValue = "";
    public ZooKeeper zkConnect( ) throws IOException {
        String path = "127.0.0.1:2181";
        zookeeper = new ZooKeeper(path, 20 * 1000, null);
        return zookeeper;
    }

    public void createZnode(String path, byte[] value, Watcher watcher, CreateMode node ) throws KeeperException, InterruptedException {
        zookeeper.create(path, value, ZooDefs.Ids.OPEN_ACL_UNSAFE, node);
    }

    public String getZnodeValue(final String path ) throws KeeperException, InterruptedException {
        byte[] data = zookeeper.getData(path, new Watcher() {
            @Override
            public void process(WatchedEvent watchedEvent) {
                triggerWatch(path);
            }
        }, new Stat());
        oldValue = new String(data);
        return new String(data);
    }

    public boolean triggerWatch (String path) {
        byte[] data = new byte[0];
        try {
            data = zookeeper.getData(path, new Watcher() {
                @Override
                public void process(WatchedEvent watchedEvent) {
                    triggerWatch(path);
                }
            }, new Stat());
        } catch (KeeperException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        newValue = new String(data);
        if (oldValue.equals(newValue)) {
            System.out.println("on change");
            return false;
        } else {
            System.out.println("oldvalue: " + oldValue + "new value: "  + newValue);
            oldValue = newValue;
            return true;
        }
    }

    public static void main(String[] args) throws IOException, KeeperException, InterruptedException {
        //创建
        Demo1 zookeeperWatchDemo = new Demo1();
        ZooKeeper zooKeeper = zookeeperWatchDemo.zkConnect();
        String path = "/root";
        String value = "rootValue";

        String child1value="child1 API测试";
        String child1path = "/root/child1";

        String child2value="child2 API测试";
        String child2path = "/root/child2";

        if (zooKeeper.exists(path, false) == null) {
            zookeeperWatchDemo.createZnode(path, value.getBytes(), null, CreateMode.PERSISTENT);
            zookeeperWatchDemo.createZnode(child1path, child1value.getBytes(), null, CreateMode.PERSISTENT);
            zookeeperWatchDemo.createZnode(child2path, child2value.getBytes(), null, CreateMode.PERSISTENT);
        }

        String znodeValue = zookeeperWatchDemo.getZnodeValue(path);
        String znodeValue1 = zookeeperWatchDemo.getZnodeValue(child1path);
        String znodeValue2 = zookeeperWatchDemo.getZnodeValue(child2path);
        System.out.println(znodeValue);
        System.out.println(znodeValue1);
        System.out.println(znodeValue2);

        Thread.sleep(1000 * 60 * 50);
    }
}