Zookeeper Watcher核心机制·安全认证(ACL)·实际应用

zookeeper有watch事件，是一次性触发的，当watch监视的数据发生变化时，通知设置了该watch的client，即watcher。

同样，其watcher是监听数据发送了某些变化，那就一定会有相应的事件类型和状态类型

事件类型:

EventType.NodeCreated 节点创建
EventType.NodeDeleted节点删除
EventType.NodeDataChanged节点数据改变
EventType.NodeChildChanged子节点改变

状态类型

KeeperState.Disconnected
KeeperState.SyncConnected
KeeperState.AuthFailed
KeeperState.Expired

watcher简单示例

/**
 * Zookeeper Wathcher 
 * 本类就是一个Watcher类（实现了org.apache.zookeeper.Watcher类）
 */
public class ZooKeeperWatcher implements Watcher {

    /** 定义原子变量 */
    AtomicInteger seq = new AtomicInteger();
    /** 定义session失效时间 */
    private static final int SESSION_TIMEOUT = 10000;
    /** zookeeper服务器地址 */
    private static final String CONNECTION_ADDR = "192.168.252.132:2181";
    /** zk父路径设置 */
    private static final String PARENT_PATH = "/testWatch";
    /** zk子路径设置 */
    private static final String CHILDREN_PATH = "/testWatch/children";
    /** 进入标识 */
    private static final String LOG_PREFIX_OF_MAIN = "【Main】";
    /** zk变量 */
    private ZooKeeper zk = null;
    /** 信号量设置，用于等待zookeeper连接建立之后 通知阻塞程序继续向下执行 */
    private CountDownLatch connectedSemaphore = new CountDownLatch(1);

    /**
     * 创建ZK连接
     * @param connectAddr ZK服务器地址列表
     * @param sessionTimeout Session超时时间
     */
    public void createConnection(String connectAddr, int sessionTimeout) {
        this.releaseConnection();
        try {
            zk = new ZooKeeper(connectAddr, sessionTimeout, this);
            System.out.println(LOG_PREFIX_OF_MAIN + "开始连接ZK服务器");
            connectedSemaphore.await();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 关闭ZK连接
     */
    public void releaseConnection() {
        if (this.zk != null) {
            try {
                this.zk.close();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 创建节点
     * @param path 节点路径
     * @param data 数据内容
     * @return boolean
     */
    public boolean createPath(String path, String data) {
        try {
            //watcher是一次性的
            //设置监控(由于zookeeper的监控都是一次性的所以 每次必须设置监控)
            this.zk.exists(path, true);
            System.out.println(LOG_PREFIX_OF_MAIN + "节点创建成功, Path: " + 
                               this.zk.create(  /**路径*/ 
                                                path, 
                                                /**数据*/
                                                data.getBytes(), 
                                                /**所有可见*/
                                                Ids.OPEN_ACL_UNSAFE, 
                                                /**永久存储*/
                                                CreateMode.PERSISTENT ) +   
                               ", content: " + data);
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
        return true;
    }

    /**
     * 读取指定节点数据内容
     * @param path 节点路径
     * @return
     */
    public String readData(String path, boolean needWatch) {
        try {
            return new String(this.zk.getData(path, needWatch, null));
        } catch (Exception e) {
            e.printStackTrace();
            return "";
        }
    }

    /**
     * 更新指定节点数据内容
     * @param path 节点路径
     * @param data 数据内容
     * @return
     */
    public boolean writeData(String path, String data) {
        try {
            System.out.println(LOG_PREFIX_OF_MAIN + "更新数据成功，path：" + path + ", stat: " +
                                this.zk.setData(path, data.getBytes(), -1));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }

    /**
     * 删除指定节点
     * 
     * @param path
     *            节点path
     */
    public void deleteNode(String path) {
        try {
            this.zk.delete(path, -1);
            System.out.println(LOG_PREFIX_OF_MAIN + "删除节点成功，path：" + path);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 判断指定节点是否存在
     * @param path 节点路径
     */
    public Stat exists(String path, boolean needWatch) {
        try {
            return this.zk.exists(path, needWatch);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 获取子节点
     * @param path 节点路径
     */
    private List<String> getChildren(String path, boolean needWatch) {
        try {
            return this.zk.getChildren(path, needWatch);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 删除所有节点
     */
    public void deleteAllTestPath() {
        if(this.exists(CHILDREN_PATH, false) != null){
            this.deleteNode(CHILDREN_PATH);
        }
        if(this.exists(PARENT_PATH, false) != null){
            this.deleteNode(PARENT_PATH);
        }       
    }

    /**
     * 收到来自Server的Watcher通知后的处理。
     */
    @Override
    public void process(WatchedEvent event) {

        System.out.println("进入 process 。。。。。event = " + event);

        try {
            Thread.sleep(200);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        if (event == null) {
            return;
        }

        // 连接状态
        KeeperState keeperState = event.getState();
        // 事件类型
        EventType eventType = event.getType();
        // 受影响的path
        String path = event.getPath();

        String logPrefix = "【Watcher-" + this.seq.incrementAndGet() + "】";

        System.out.println(logPrefix + "收到Watcher通知");
        System.out.println(logPrefix + "连接状态:\t" + keeperState.toString());
        System.out.println(logPrefix + "事件类型:\t" + eventType.toString());

        if (KeeperState.SyncConnected == keeperState) {
            // 成功连接上ZK服务器
            if (EventType.None == eventType) {
                System.out.println(logPrefix + "成功连接上ZK服务器");
                connectedSemaphore.countDown();
            } 
            //创建节点
            else if (EventType.NodeCreated == eventType) {
                System.out.println(logPrefix + "节点创建");
                try {
                    Thread.sleep(100);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                this.exists(path, true);
            } 
            //更新节点
            else if (EventType.NodeDataChanged == eventType) {
                System.out.println(logPrefix + "节点数据更新");
                System.out.println("我看看走不走这里........");
                try {
                    Thread.sleep(100);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println(logPrefix + "数据内容: " + this.readData(PARENT_PATH, true));
            } 
            //更新子节点
            else if (EventType.NodeChildrenChanged == eventType) {
                System.out.println(logPrefix + "子节点变更");
                try {
                    Thread.sleep(3000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println(logPrefix + "子节点列表：" + this.getChildren(PARENT_PATH, true));
            } 
            //删除节点
            else if (EventType.NodeDeleted == eventType) {
                System.out.println(logPrefix + "节点 " + path + " 被删除");
            }
            else ;
        } 
        else if (KeeperState.Disconnected == keeperState) {
            System.out.println(logPrefix + "与ZK服务器断开连接");
        } 
        else if (KeeperState.AuthFailed == keeperState) {
            System.out.println(logPrefix + "权限检查失败");
        } 
        else if (KeeperState.Expired == keeperState) {
            System.out.println(logPrefix + "会话失效");
        }
        else ;

        System.out.println("--------------------------------------------");

    }

    /**
     * <B>方法名称：</B>测试zookeeper监控<BR>
     * <B>概要说明：</B>主要测试watch功能<BR>
     * @param args
     * @throws Exception
     */
    public static void main(String[] args) throws Exception {

        //建立watcher
        ZooKeeperWatcher zkWatch = new ZooKeeperWatcher();
        //创建连接
        zkWatch.createConnection(CONNECTION_ADDR, SESSION_TIMEOUT);
        //System.out.println(zkWatch.zk.toString());

        Thread.sleep(1000);

        // 清理节点
        zkWatch.deleteAllTestPath();

        if (zkWatch.createPath(PARENT_PATH, System.currentTimeMillis() + "")) {

            Thread.sleep(1000);         

            // 读取数据
            System.out.println("---------------------- read parent ----------------------------");
            zkWatch.readData(PARENT_PATH, true);

            // 读取子节点
            System.out.println("---------------------- read children path ----------------------------");
            zkWatch.getChildren(PARENT_PATH, true);

            // 更新数据
            zkWatch.writeData(PARENT_PATH, System.currentTimeMillis() + "");

            Thread.sleep(1000);

        // 创建子节点
            zkWatch.createPath(CHILDREN_PATH, System.currentTimeMillis() + "");
            Thread.sleep(1000);

            zkWatch.writeData(CHILDREN_PATH, System.currentTimeMillis() + "");
        }

        Thread.sleep(50000);
    // 清理节点
        zkWatch.deleteAllTestPath();
        Thread.sleep(1000);
        zkWatch.releaseConnection();
    }

}

Zookeeper中的Access Control(ACL)

概述
传统的文件系统中，ACL分为两个维度，一个是属组，一个是权限，子目录/文件默认继承父目录的ACL。而在Zookeeper中，node的ACL是没有继承关系的，是独立控制的。Zookeeper的ACL，可以从三个维度来理解：一是scheme; 二是user; 三是permission，通常表示为scheme:id:permissions, 下面从这三个方面分别来介绍：

scheme: scheme对应于采用哪种方案来进行权限管理，zookeeper实现了一个pluggable的ACL方案，可以通过扩展scheme，来扩展ACL的机制。zookeeper-3.4.4缺省支持下面几种scheme:
- world: 它下面只有一个id, 叫anyone, world:anyone代表任何人，zookeeper中对所有人有权限的结点就是属于world:anyone的
- auth: 它不需要id, 只要是通过authentication的user都有权限（zookeeper支持通过kerberos来进行authencation, 也支持username/password形式的authentication)
- digest: 它对应的id为username:BASE64(SHA1(password))，它需要先通过username:password形式的authentication
- ip: 它对应的id为客户机的IP地址，设置的时候可以设置一个ip段，比如ip:192.168.1.0/16, 表示匹配前16个bit的IP段
- super: 在这种scheme情况下，对应的id拥有超级权限，可以做任何事情(cdrwa)
- sasl: sasl的对应的id，是一个通过sasl authentication用户的id，zookeeper-3.4.4中的sasl authentication是通过kerberos来实现的，也就是说用户只有通过了kerberos认证，才能访问它有权限的node.

2 . id: id与scheme是紧密相关的，具体的情况在上面介绍scheme的过程都已介绍，这里不再赘述。
3. permission: zookeeper目前支持下面一些权限：

CREATE(c): 创建权限，可以在在当前node下创建child node DELETE(d): 删除权限，可以删除当前的node
READ(r): 读权限，可以获取当前node的数据，可以list当前node所有的child nodes WRITE(w):
写权限，可以向当前node写数据 ADMIN(a): 管理权限，可以设置当前node的permission

digest模式下的示例

public class ZookeeperAuth implements Watcher {

    /** 连接地址 */
    final static String CONNECT_ADDR = "192.168.252.132:2181";
    /** 测试路径 */
    final static String PATH = "/testAuth";
    final static String PATH_DEL = "/testAuth/delNode";
    /** 认证类型 */
    final static String authentication_type = "digest";
    /** 认证正确方法 */
    final static String correctAuthentication = "123456";
    /** 认证错误方法 */
    final static String badAuthentication = "654321";

    static ZooKeeper zk = null;
    /** 计时器 */
    AtomicInteger seq = new AtomicInteger();
    /** 标识 */
    private static final String LOG_PREFIX_OF_MAIN = "【Main】";

    private CountDownLatch connectedSemaphore = new CountDownLatch(1);

    @Override
    public void process(WatchedEvent event) {
        try {
            Thread.sleep(200);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        if (event==null) {
            return;
        }
        // 连接状态
        KeeperState keeperState = event.getState();
        // 事件类型
        EventType eventType = event.getType();
        // 受影响的path
        String path = event.getPath();

        String logPrefix = "【Watcher-" + this.seq.incrementAndGet() + "】";

        System.out.println(logPrefix + "收到Watcher通知");
        System.out.println(logPrefix + "连接状态:\t" + keeperState.toString());
        System.out.println(logPrefix + "事件类型:\t" + eventType.toString());
        if (KeeperState.SyncConnected == keeperState) {
            // 成功连接上ZK服务器
            if (EventType.None == eventType) {
                System.out.println(logPrefix + "成功连接上ZK服务器");
                connectedSemaphore.countDown();
            } 
        } else if (KeeperState.Disconnected == keeperState) {
            System.out.println(logPrefix + "与ZK服务器断开连接");
        } else if (KeeperState.AuthFailed == keeperState) {
            System.out.println(logPrefix + "权限检查失败");
        } else if (KeeperState.Expired == keeperState) {
            System.out.println(logPrefix + "会话失效");
        }
        System.out.println("--------------------------------------------");
    }
    /**
     * 创建ZK连接
     * 
     * @param connectString
     *            ZK服务器地址列表
     * @param sessionTimeout
     *            Session超时时间
     */
    public void createConnection(String connectString, int sessionTimeout) {
        this.releaseConnection();
        try {
            zk = new ZooKeeper(connectString, sessionTimeout, this);
            //添加节点授权
            zk.addAuthInfo(authentication_type,correctAuthentication.getBytes());
            System.out.println(LOG_PREFIX_OF_MAIN + "开始连接ZK服务器");
            //倒数等待
            connectedSemaphore.await();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 关闭ZK连接
     */
    public void releaseConnection() {
        if (this.zk!=null) {
            try {
                this.zk.close();
            } catch (InterruptedException e) {
            }
        }
    }

    /**
     * 
     * <B>方法名称：</B>测试函数<BR>
     * <B>概要说明：</B>测试认证<BR>
     * @param args
     * @throws Exception
     */
    public static void main(String[] args) throws Exception {

        ZookeeperAuth testAuth = new ZookeeperAuth();
        testAuth.createConnection(CONNECT_ADDR,2000);
        List<ACL> acls = new ArrayList<ACL>(1);
        for (ACL ids_acl : Ids.CREATOR_ALL_ACL) {
            acls.add(ids_acl);
        }

        try {
            zk.create(PATH, "init content".getBytes(), acls, CreateMode.PERSISTENT);
            System.out.println("使用授权key：" + correctAuthentication + "创建节点："+ PATH + ", 初始内容是: init content");
        } catch (Exception e) {
            e.printStackTrace();
        }
        try {
            zk.create(PATH_DEL, "will be deleted! ".getBytes(), acls, CreateMode.PERSISTENT);
            System.out.println("使用授权key：" + correctAuthentication + "创建节点："+ PATH_DEL + ", 初始内容是: init content");
        } catch (Exception e) {
            e.printStackTrace();
        }

        // 获取数据
        getDataByNoAuthentication();
        getDataByBadAuthentication();
        getDataByCorrectAuthentication();

        // 更新数据
        updateDataByNoAuthentication();
        updateDataByBadAuthentication();
        updateDataByCorrectAuthentication();

        // 删除数据
        deleteNodeByBadAuthentication();
        deleteNodeByNoAuthentication();
        deleteNodeByCorrectAuthentication();
        //
        Thread.sleep(1000);

        deleteParent();
        //释放连接
        testAuth.releaseConnection();
    }
    /** 获取数据：采用错误的密码 */
    static void getDataByBadAuthentication() {
        String prefix = "[使用错误的授权信息]";
        try {
            ZooKeeper badzk = new ZooKeeper(CONNECT_ADDR, 2000, null);
            //授权
            badzk.addAuthInfo(authentication_type,badAuthentication.getBytes());
            Thread.sleep(2000);
            System.out.println(prefix + "获取数据：" + PATH);
            System.out.println(prefix + "成功获取数据：" + badzk.getData(PATH, false, null));
        } catch (Exception e) {
            System.err.println(prefix + "获取数据失败，原因：" + e.getMessage());
        }
    }

    /** 获取数据：不采用密码 */
    static void getDataByNoAuthentication() {
        String prefix = "[不使用任何授权信息]";
        try {
            System.out.println(prefix + "获取数据：" + PATH);
            ZooKeeper nozk = new ZooKeeper(CONNECT_ADDR, 2000, null);
            Thread.sleep(2000);
            System.out.println(prefix + "成功获取数据：" + nozk.getData(PATH, false, null));
        } catch (Exception e) {
            System.err.println(prefix + "获取数据失败，原因：" + e.getMessage());
        }
    }

    /** 采用正确的密码 */
    static void getDataByCorrectAuthentication() {
        String prefix = "[使用正确的授权信息]";
        try {
            System.out.println(prefix + "获取数据：" + PATH);

            System.out.println(prefix + "成功获取数据：" + zk.getData(PATH, false, null));
        } catch (Exception e) {
            System.out.println(prefix + "获取数据失败，原因：" + e.getMessage());
        }
    }

    /**
     * 更新数据：不采用密码
     */
    static void updateDataByNoAuthentication() {

        String prefix = "[不使用任何授权信息]";

        System.out.println(prefix + "更新数据： " + PATH);
        try {
            ZooKeeper nozk = new ZooKeeper(CONNECT_ADDR, 2000, null);
            Thread.sleep(2000);
            Stat stat = nozk.exists(PATH, false);
            if (stat!=null) {
                nozk.setData(PATH, prefix.getBytes(), -1);
                System.out.println(prefix + "更新成功");
            }
        } catch (Exception e) {
            System.err.println(prefix + "更新失败，原因是：" + e.getMessage());
        }
    }

    /**
     * 更新数据：采用错误的密码
     */
    static void updateDataByBadAuthentication() {

        String prefix = "[使用错误的授权信息]";

        System.out.println(prefix + "更新数据：" + PATH);
        try {
            ZooKeeper badzk = new ZooKeeper(CONNECT_ADDR, 2000, null);
            //授权
            badzk.addAuthInfo(authentication_type,badAuthentication.getBytes());
            Thread.sleep(2000);
            Stat stat = badzk.exists(PATH, false);
            if (stat!=null) {
                badzk.setData(PATH, prefix.getBytes(), -1);
                System.out.println(prefix + "更新成功");
            }
        } catch (Exception e) {
            System.err.println(prefix + "更新失败，原因是：" + e.getMessage());
        }
    }

    /**
     * 更新数据：采用正确的密码
     */
    static void updateDataByCorrectAuthentication() {

        String prefix = "[使用正确的授权信息]";

        System.out.println(prefix + "更新数据：" + PATH);
        try {
            Stat stat = zk.exists(PATH, false);
            if (stat!=null) {
                zk.setData(PATH, prefix.getBytes(), -1);
                System.out.println(prefix + "更新成功");
            }
        } catch (Exception e) {
            System.err.println(prefix + "更新失败，原因是：" + e.getMessage());
        }
    }

    /**
     * 不使用密码 删除节点
     */
    static void deleteNodeByNoAuthentication() throws Exception {

        String prefix = "[不使用任何授权信息]";

        try {
            System.out.println(prefix + "删除节点：" + PATH_DEL);
            ZooKeeper nozk = new ZooKeeper(CONNECT_ADDR, 2000, null);
            Thread.sleep(2000);
            Stat stat = nozk.exists(PATH_DEL, false);
            if (stat!=null) {
                nozk.delete(PATH_DEL,-1);
                System.out.println(prefix + "删除成功");
            }
        } catch (Exception e) {
            System.err.println(prefix + "删除失败，原因是：" + e.getMessage());
        }
    }

    /**
     * 采用错误的密码删除节点
     */
    static void deleteNodeByBadAuthentication() throws Exception {

        String prefix = "[使用错误的授权信息]";

        try {
            System.out.println(prefix + "删除节点：" + PATH_DEL);
            ZooKeeper badzk = new ZooKeeper(CONNECT_ADDR, 2000, null);
            //授权  使用错误的授权码badAuthentication
            badzk.addAuthInfo(authentication_type,badAuthentication.getBytes());
            Thread.sleep(2000);
            Stat stat = badzk.exists(PATH_DEL, false);
            if (stat!=null) {
                badzk.delete(PATH_DEL, -1);
                System.out.println(prefix + "删除成功");
            }
        } catch (Exception e) {
            System.err.println(prefix + "删除失败，原因是：" + e.getMessage());
        }
    }

    /**
     * 使用正确的密码删除节点
     */
    static void deleteNodeByCorrectAuthentication() throws Exception {

        String prefix = "[使用正确的授权信息]";

        try {
            System.out.println(prefix + "删除节点：" + PATH_DEL);
            Stat stat = zk.exists(PATH_DEL, false);
            if (stat!=null) {
                zk.delete(PATH_DEL, -1);
                System.out.println(prefix + "删除成功");
            }
        } catch (Exception e) {
            System.out.println(prefix + "删除失败，原因是：" + e.getMessage());
        }
    }

    /**
     * 使用正确的密码删除节点
     */
    static void deleteParent() throws Exception {
        try {
            Stat stat = zk.exists(PATH_DEL, false);
            if (stat == null) {
                zk.delete(PATH, -1);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

Zookeeper Watcher核心机制·安全认证(ACL)·实际应用

zookeeper有watch事件，是一次性触发的，当watch监视的数据发生变化时，通知设置了该watch的client，即watcher。

同样，其watcher是监听数据发送了某些变化，那就一定会有相应的事件类型和状态类型

watcher简单示例

Zookeeper中的Access Control(ACL)

Java NIO網絡編程

Java SocketIO網絡編程

Vue與axios整合時，訪問Vue實例

Retrofit與RxJava實踐

關於HashMap那些事

https://yachay.unat.edu.pe/blog/index.php?comment_area=format_blog&comment_component=blog&comment_co

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