Zookeeper——java操作客户端（有代码注释可运行）

r囧r小猫 2023-07-19 14:30 35阅读 0赞

先引入Zookeeper原生的jar包

<dependency>
                <groupId>org.apache.zookeeper</groupId>
                <artifactId>zookeeper</artifactId>
                <version>3.6.0</version>
            </dependency>

其他看代码和注释

public class CrudZookeeper { 
        
        private static CountDownLatch countDownLatch = new CountDownLatch(1);
        //zookeeper的连接路径
        private final static String ZOOKEEP_UER="49.233.186.66:2181";
    
        public static void main(String[] args) throws Exception { 
            ZooKeeper zooKeeper = new ZooKeeper(ZOOKEEP_UER, 5000, new Watcher() { 
                @Override
                public void process(WatchedEvent watchedEvent) { 
                    //如果连接上了
                        if(watchedEvent.getState()==Event.KeeperState.SyncConnected){ 
                            System.out.println("连接上了");
                            countDownLatch.countDown();
                        }
                        //如果节点发生了变化
                    if(watchedEvent.getType()==Event.EventType.NodeDataChanged){ 
                        System.out.println("节点数据发生变化，节点路径为"+watchedEvent.getPath());
                    }
                }
            });
            //防止zookeeper还没连接上，代码就往下走
            countDownLatch.await();
            //stat是节点的一些相关状态信息
            Stat stat = new Stat();
            //创建节点， 路径/值/ACL权限/节点类型
         // zooKeeper.create("/ccc","value2".getBytes(),ZooDefs.Ids.OPEN_ACL_UNSAFE,CreateMode.PERSISTENT);
            //获取节点, 路径/是否监听/stat
            byte[] data = zooKeeper.getData("/ccc", true, stat);
            System.out.println(new String(data));
            System.out.println(stat);
            //修改数据 version传入-1时不进行版本维护
            zooKeeper.setData("/ccc","value2".getBytes(),-1);
            //删除数据
            zooKeeper.delete("/ccc",-1);
    
            //获取子节点 watch代表当节点或数据发生改变时通知客户端
            List<String> children = zooKeeper.getChildren("/testauth", true);
    
        }
    }

值得注意的是，watch机制是有有效性的，一次设置为true，就只能监听一次  
如下代码，当第三行没有时，上面代码种的监听修改便只能打印一次！  
![在这里插入图片描述][20200331105805151.png]

[20200331105805151.png]: /images/20230528/e43ddbd4467d4df58372c9810ba56b48.png