Zookeeper API

2022年2月23日22:59:20 发表评论 128 views
import org.apache.zookeeper.*;
import org.apache.zookeeper.data.Stat;
import org.junit.Before;
import org.junit.Test;

import java.io.IOException;
import java.util.List;

public class ZK {
    private static String connectString = "bigdata166:2181,bigdata167:2181,bigdata168:2181";
    private static int sessionTimeout = 2000;
    private ZooKeeper zkClient = null;

    /**
     * 监听方法,首先运行
     *
     * @throws IOException
     */
    @Before
    public void init() throws IOException {
        zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
            @Override
            public void process(WatchedEvent watchedEvent) {
                //获取业务
                System.out.println(watchedEvent.getType() + "===" + watchedEvent.getPath());
                try {
                    zkClient.getChildren("/", true);
                } catch (KeeperException e) {
                    e.printStackTrace();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

            }
        });
    }

    /**
     * 参数4:临时,永久,序列化 永久+序列化,临时——+序列化
     *
     * @throws KeeperException
     * @throws InterruptedException
     */
    @Test
    public void create() throws KeeperException, InterruptedException {
        zkClient.create("/bigdata16",
                "TestShall".getBytes(),
                ZooDefs.Ids.OPEN_ACL_UNSAFE,
                CreateMode.PERSISTENT);//全部开放权限,创建永久权限
    }

    /**
     * 判断节点是否存在
     * @throws KeeperException
     * @throws InterruptedException
     */
    @Test
    public void exist() throws KeeperException, InterruptedException {
        Stat exists = zkClient.exists("/bigdata16", false);
        System.out.println(exists==null? "无此节点":"有此节点");
    }

    /**
     * 获取子节点(坑:当Sting中某台机器关掉Server后,会报错)
     * @throws KeeperException
     * @throws InterruptedException
     */
    @Test
    public void getChildren() throws KeeperException, InterruptedException {
        List<String> children = zkClient.getChildren("/", true);
        for (String child : children) {
            System.out.println(child);
        }

        Thread.sleep(Long.MAX_VALUE);
        
    }
}

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