Zookeeper 监控指定节点数据变化

一、监控数据变化,并且只监控一次

1、java代码

public class ZkDemo {
    public static Logger logger = Logger.getLogger(ZkDemo.class);

    private static String connectString = "192.168.229.129:2181";
    private static int SESSION_TIME_OUT = 60 * 1000;
    private ZooKeeper zk = null;
    private String newValue = null;

    public String getOldValue() {
        return oldValue;
    }

    public void setOldValue(String oldValue) {
        this.oldValue = oldValue;
    }

    private String oldValue = null;

    public ZooKeeper getZk() {
        return zk;
    }

    public void setZk(ZooKeeper zk) {
        this.zk = zk;
    }

    public String getNewValue() {
        return newValue;
    }

    public void setNewValue(String newValue) {
        this.newValue = newValue;
    }

    /**
     * 启动并连接 Zookeeper
     */
    public ZooKeeper start() throws IOException {
        return new ZooKeeper(connectString, SESSION_TIME_OUT, new Watcher() {
            @Override
            public void process(WatchedEvent watchedEvent) {
            }
        });
    }

    /**
     * 创建节点
     */
    public void createNode(String path, String data) throws IOException, KeeperException, InterruptedException {
        // 返回当前节点的名称
        String currentNode = zk.create(path, data.getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
        logger.info("create zookeeper node success,currentNode******" + currentNode);
    }


    /**
     * 获取当前节点的数据,并且设置观察者
     */
    public String getNodeData(String path) throws IOException, KeeperException, InterruptedException {
        byte[] oldData = zk.getData(path, new Watcher() {
            @Override
            public void process(WatchedEvent watchedEvent) {
                try {
                    // 该节点的值是否发生变化的标识,true:发生变化,false:未发生变化
                    Boolean flag = triggerWathcher(path);
                    logger.info("*******flag:" + flag);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }, new Stat());
        // 获取当前节点的值,如果当前节点的值发生变化,将新值覆盖原先的值
        if (newValue != null && !oldValue.equals(newValue)) {
            oldValue = newValue;
        }
        oldValue = new String(oldData, "UTF-8");
        return oldValue;
    }

    /**
     * 触发观察者
     */
    public Boolean triggerWathcher(String path) throws IOException, KeeperException, InterruptedException {
        byte[] newData = zk.getData(path, false, new Stat());
        newValue = new String(newData, "UTF-8");

        if (oldValue.equals(newValue)) {
            logger.info("******this node value is no change");
            return false;
        } else {
            logger.info("******oldValue:" + oldValue + "******" + "newValue:" + newValue);
            return true;
        }
    }

    public static void main(String[] args) throws InterruptedException, IOException, KeeperException {
        ZkDemo zkDemo = new ZkDemo();
        zkDemo.setZk(zkDemo.start());
        // 如果不存在 /xiaomao 这个节点,那么就创建该节点
        if (zkDemo.getZk().exists("/xiaomao", false) == null) {
            zkDemo.createNode("/xiaomao", "123");
        }
        zkDemo.getNodeData("/xiaomao");
        Thread.sleep(Long.MAX_VALUE);
    }
}

2、执行完 java 代码 zookeeper 客户端的变化情况

// 查看根节点下所有的子节点,可以看到 /xiaomao 这个子节点已经创建出来了
[zk: localhost:2181(CONNECTED) 75] ls /
[zookeeper, xiaomao]
// 获取节点 /xiaomao 的值,可以看到它的值就是我们设置的 123
[zk: localhost:2181(CONNECTED) 76] get /xiaomao
123
cZxid = 0x143
ctime = Mon Oct 12 08:00:54 CST 2020
mZxid = 0x143
mtime = Mon Oct 12 08:00:54 CST 2020
pZxid = 0x143
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 3
numChildren = 0

3、手动在客户端变更节点 /xiaomao 的值

// 手动将节点 /xiaomao 的值修改为456
[zk: localhost:2181(CONNECTED) 77] set /xiaomao 456
cZxid = 0x143
ctime = Mon Oct 12 08:00:54 CST 2020
mZxid = 0x144
mtime = Mon Oct 12 08:01:18 CST 2020
pZxid = 0x143
cversion = 0
dataVersion = 1
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 3
numChildren = 0
// 再一次手动将节点 /xiaomao 的值修改为789
[zk: localhost:2181(CONNECTED) 78] set /xiaomao 789
cZxid = 0x143
ctime = Mon Oct 12 08:00:54 CST 2020
mZxid = 0x145
mtime = Mon Oct 12 08:01:23 CST 2020
pZxid = 0x143
cversion = 0
dataVersion = 2
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 3
numChildren = 0
// 获取节点 /xiaomao 现在的值,可以看到值为789
[zk: localhost:2181(CONNECTED) 79] get /xiaomao
789
cZxid = 0x143
ctime = Mon Oct 12 08:00:54 CST 2020
mZxid = 0x145
mtime = Mon Oct 12 08:01:23 CST 2020
pZxid = 0x143
cversion = 0
dataVersion = 2
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 3
numChildren = 0

4、控制台变化

// 当前节点的名称
2020-10-12 00:00:56,199 INFO [ZkDemo] - create zookeeper node success,currentNode******/xiaomao
2020-10-12 00:00:56,203 DEBUG [org.apache.zookeeper.ClientCnxn] - Reading reply sessionid:0x100000365a40014, packet:: 
2020-10-12 00:01:09,538 DEBUG [org.apache.zookeeper.ClientCnxn] - Got ping response for sessionid: 0x100000365a40014 after 2ms
2020-10-12 00:01:20,361 DEBUG [org.apache.zookeeper.ClientCnxn] - Got notification sessionid:0x100000365a40014
2020-10-12 00:01:20,362 DEBUG [org.apache.zookeeper.ClientCnxn] - Got WatchedEvent state:SyncConnected 
2020-10-12 00:01:20,363 DEBUG [org.apache.zookeeper.ClientCnxn] - Got ping response for sessionid: 0x100000365a40014 after 2ms
2020-10-12 00:01:20,364 DEBUG [org.apache.zookeeper.ClientCnxn] - Reading reply sessionid:0x100000365a40014, packet:: 
// 虽然我们在 Zookeeper 的控制台设置了两次值,一次是设置为 456 ,另外一次设置为 789 ,但是由于我们是一次性的监控,所以控制台只有一次变化的值
2020-10-12 00:01:20,364 INFO [ZkDemo] - ******oldValue:123******newValue:456
2020-10-12 00:01:20,364 INFO [ZkDemo] - *******flag:true

　　

二、监控数据变化,动态监控(多次监控)

1、java代码

public class ZkDemo {
    public static Logger logger = Logger.getLogger(ZkDemo.class);

    private static String connectString = "192.168.229.129:2181";
    private static int SESSION_TIME_OUT = 60 * 1000;
    private ZooKeeper zk = null;
    private String newValue = null;

    public String getOldValue() {
        return oldValue;
    }

    public void setOldValue(String oldValue) {
        this.oldValue = oldValue;
    }

    private String oldValue = null;

    public ZooKeeper getZk() {
        return zk;
    }

    public void setZk(ZooKeeper zk) {
        this.zk = zk;
    }

    public String getNewValue() {
        return newValue;
    }

    public void setNewValue(String newValue) {
        this.newValue = newValue;
    }

    /**
     * 启动并连接 Zookeeper
     */
    public ZooKeeper start() throws IOException {
        return new ZooKeeper(connectString, SESSION_TIME_OUT, new Watcher() {
            @Override
            public void process(WatchedEvent watchedEvent) {
            }
        });
    }

    /**
     * 创建节点
     */
    public void createNode(String path, String data) throws IOException, KeeperException, InterruptedException {
        // 返回当前节点的名称
        String currentNode = zk.create(path, data.getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
        logger.info("create zookeeper node success,currentNode******" + currentNode);
    }


    /**
     * 获取当前节点的数据,并且设置观察者
     */
    public String getNodeData(String path) throws IOException, KeeperException, InterruptedException {
        byte[] oldData = zk.getData(path, new Watcher() {
            @Override
            public void process(WatchedEvent watchedEvent) {
                try {
                    // 该节点的值是否发生变化的标识,true:发生变化,false:未发生变化
                    Boolean flag = triggerWathcher(path);
                    logger.info("*******flag:" + flag);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }, new Stat());
        oldValue = new String(oldData, "UTF-8");
        return oldValue;
    }

    /**
     * 触发观察者
     */
    public Boolean triggerWathcher(String path) throws IOException, KeeperException, InterruptedException {
        byte[] newData = zk.getData(path, new Watcher() {
            @Override
            public void process(WatchedEvent watchedEvent) {
                try {
                    // 回调自身,类似于递归,可以实现实时监控
                    triggerWathcher(path);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }, new Stat());
        newValue = new String(newData, "UTF-8");

        if (oldValue.equals(newValue)) {
            logger.info("******this node value is no change");
            return false;
        } else {
            logger.info("******oldValue:" + oldValue + "******" + "newValue:" + newValue);
            // 如果值发生了变化,将新值覆盖原来的值
            oldValue = newValue;
            return true;
        }
    }

    public static void main(String[] args) throws InterruptedException, IOException, KeeperException {
        ZkDemo zkDemo = new ZkDemo();
        zkDemo.setZk(zkDemo.start());
        // 如果不存在 /xiaomao 这个节点,那么就创建该节点
        if (zkDemo.getZk().exists("/xiaomaomao", false) == null) {
            zkDemo.createNode("/xiaomaomao", "123");
        }
        zkDemo.getNodeData("/xiaomaomao");
        Thread.sleep(Long.MAX_VALUE);
    }
}

2、Zookeeper 客户端操作

// 获取根节点的值
[zk: localhost:2181(CONNECTED) 82] ls /
[xiaomaomao, zookeeper]
[zk: localhost:2181(CONNECTED) 83] get /xiaomaomao
123
cZxid = 0x149
ctime = Mon Oct 12 08:10:14 CST 2020
mZxid = 0x149
mtime = Mon Oct 12 08:10:14 CST 2020
pZxid = 0x149
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 3
numChildren = 0
// 修改节点 /xiaomaomao 的值(原先是 123 ,设置一个相同的值,看一下效果)
[zk: localhost:2181(CONNECTED) 84] set /xiaomaomao 123
cZxid = 0x149
ctime = Mon Oct 12 08:10:14 CST 2020
mZxid = 0x14a
mtime = Mon Oct 12 08:10:32 CST 2020
pZxid = 0x149
cversion = 0
dataVersion = 1
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 3
numChildren = 0
// 修改节点 /xiaomaomao 的值为 456
[zk: localhost:2181(CONNECTED) 85] set /xiaomaomao 456
cZxid = 0x149
ctime = Mon Oct 12 08:10:14 CST 2020
mZxid = 0x14b
mtime = Mon Oct 12 08:10:38 CST 2020
pZxid = 0x149
cversion = 0
dataVersion = 2
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 3
numChildren = 0
// 修改节点 /xiaomaomao 的值为 789
[zk: localhost:2181(CONNECTED) 86] set /xiaomaomao 789
cZxid = 0x149
ctime = Mon Oct 12 08:10:14 CST 2020
mZxid = 0x14c
mtime = Mon Oct 12 08:10:42 CST 2020
pZxid = 0x149
cversion = 0
dataVersion = 3
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 3
numChildren = 0

3、控制台变化

// 设置一个相同的值时,控制台的变化情况
2020-10-12 00:10:33,553 INFO [ZkDemo] - ******this node value is no change
2020-10-12 00:10:33,553 INFO [ZkDemo] - *******flag:false
2020-10-12 00:10:39,593 DEBUG [org.apache.zookeeper.ClientCnxn] - Got notification sessionid:0x100000365a40015
2020-10-12 00:10:39,594 DEBUG [org.apache.zookeeper.ClientCnxn] - Got WatchedEvent state:SyncConnected 
2020-10-12 00:10:39,595 DEBUG [org.apache.zookeeper.ClientCnxn] - Reading reply sessionid:0x100000365a40015, 
// 将节点的值修改为 456
2020-10-12 00:10:39,595 INFO [ZkDemo] - ******oldValue:123******newValue:456
2020-10-12 00:10:43,993 DEBUG [org.apache.zookeeper.ClientCnxn] - Got notification sessionid:0x100000365a40015
2020-10-12 00:10:43,993 DEBUG [org.apache.zookeeper.ClientCnxn] - Got WatchedEvent state:SyncConnected type:
2020-10-12 00:10:43,995 DEBUG [org.apache.zookeeper.ClientCnxn] - Reading reply sessionid:0x100000365a40015, 
// 将节点的值修改为 456
2020-10-12 00:10:43,995 INFO [ZkDemo] - ******oldValue:456******newValue:789

　　

 

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原文地址：https://www.cnblogs.com/xiaomaomao/p/13787639.html