4.2.3、Zookeeper

参数：集群的每个主机名，会话时间（多长时间没有连上就不行），监视器

public class Demo01 {
    public static void main(String[] args) throws Exception {
        ZooKeeper zooKeeper = new ZooKeeper("master:2181,node1:2181,node2:2181", 3000, null);
        //创建一个节点，数据
        zooKeeper.create("/test", "test".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
        //获取数据
        Stat stat = new Stat();
        byte[] data = zooKeeper.getData("/test", true, stat);
        System.out.println(Arrays.toString(data));
    }
}

持久：断开连接，创建的节点不删除
短暂：断开连接，节点删除

操作：

public class Demo03 {
    ZooKeeper zooKeeper;
    @Before
    public void getinit()throws Exception{
        //连接,监听器
            zooKeeper = new ZooKeeper("master:2181,node1:2181,node2:2181", 2000, new Watcher() {
                public void process(WatchedEvent watchedEvent) {
                    List children = null;
                    try {
                        //获取路径监听
                        children = zooKeeper.getChildren("/", true);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                    //输出所有节点
                    for (String child : children) {
                        System.out.println(child);
                    }
                }
            });
    }
    
    //获取子节点
    @Test
    public void getChinld()throws Exception{
        List children = zooKeeper.getChildren("/", true);
        for (String child : children) {
            System.out.println(child);
        }
        Thread.sleep(Long.MAX_VALUE);
    }
    
    //判断节点是否存在
    @Test
    public void getExists()throws Exception{
        Stat exists = zooKeeper.exists("/d", false);
        System.out.println(exists==null?0:1);
    }
     //修改数据  ,-1表示忽略版本
    @Test
     public void getUpdata()throws Exception{
         Stat stat = zooKeeper.setData("/test", "123456789".getBytes(), -1);
         System.out.println(stat==null?0:1);
     }
}