zookeeper之java API使用

最新推荐文章于 2024-06-27 13:31:06 发布

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本文深入探讨了ZooKeeper中节点的同步与异步创建、获取子节点及节点数据的操作方法，包括代码示例与运行结果分析，是理解ZooKeeper节点管理机制的实用指南。

节点创建

package com.zookeeper;

import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.ZooKeeper;

import java.io.IOException;

public class CreateNodeSync {

    private static ZooKeeper zooKeeper;

    public static void main(String[] args) {
        try {
            zooKeeper = new ZooKeeper("192.168.40.135:2181", 5000, new Watcher() {
                public void process(WatchedEvent watchedEvent) {
                    if (watchedEvent.getState() == Event.KeeperState.SyncConnected) {

                        doSomeThing();
                    }
                }
            });
            System.out.println("state:{}" + zooKeeper.getState());
            Thread.sleep(Integer.MAX_VALUE);
        }
        catch (IOException e) {
            System.out.println("connect zk failed");
        }
        catch (InterruptedException e) {
            e.printStackTrace();
        }


    }

    private static void doSomeThing() {
        String path = null;
        try {
            path = zooKeeper.create("/node_4", "123".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
        }
        catch (KeeperException e) {
            e.printStackTrace();
        }
        catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("path:" + path);
    }
}

同步异步创建：

package com.zookeeper;

import org.apache.zookeeper.AsyncCallback;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.ZooKeeper;

import java.io.IOException;

public class CreateNodeASync {

    private static ZooKeeper zooKeeper;

    public static void main(String[] args) {
        try {
            zooKeeper = new ZooKeeper("192.168.40.135:2181", 5000, new Watcher() {
                public void process(WatchedEvent watchedEvent) {
                    if (watchedEvent.getState() == Event.KeeperState.SyncConnected) {
                        doSomeThing();
                    }
                }
            });
            System.out.println("state:{}" + zooKeeper.getState());
            Thread.sleep(Integer.MAX_VALUE);
        }
        catch (IOException e) {
            System.out.println("connect zk failed");
        }
        catch (InterruptedException e) {
            e.printStackTrace();
        }

    }

    private static void doSomeThing() {
        zooKeeper.create("/node_5", "123".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT, new IStringClassback(), "异步创建");
    }

    //异步调用，需要 一个回调函数
    static class IStringClassback implements AsyncCallback.StringCallback {

        /**
         * @param rc 返回码，如果异步创建成功，返回0
         * @param path  创建节点的完整路径
         * @param ctx  异步调用的上下文，。。也就是上面传下来的“创建”字符串
         * @param name  服务端返回的已经创建节点的真实路径，如果是顺序节点，那么和path不一致
         */
        public void processResult(int rc, String path, Object ctx, String name) {

            StringBuilder stringBuilder = new StringBuilder();
            stringBuilder.append("rc=" + rc).append("\n");
            stringBuilder.append("path=" + path).append("\n");
            stringBuilder.append("ctx=" + ctx).append("\n");
            stringBuilder.append("name=" + name).append("\n");
            System.out.println(stringBuilder.toString());

        }
    }
}

运行结果：

同步获取：

package com.zookeeper;

import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;

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

public class GetChildSync {

    private static ZooKeeper zooKeeper;

    public static void main(String[] args) {
        try {
            zooKeeper = new ZooKeeper("192.168.40.135:2181", 5000, new Watcher() {
                public void process(WatchedEvent watchedEvent) {
                    if (watchedEvent.getState() == Event.KeeperState.SyncConnected) {

                        doSomeThing();
                    }
                }
            });
            System.out.println("state:{}" + zooKeeper.getState());
            Thread.sleep(Integer.MAX_VALUE);
        }
        catch (IOException e) {
            System.out.println("connect zk failed");
        }
        catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    private static void doSomeThing() {
        List<String> children = null;
        try {
            //false表示不需要需要关注子节点的变化
            children = zooKeeper.getChildren("/", false);
        }
        catch (KeeperException e) {
            e.printStackTrace();
        }
        catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("children:" + children);
    }
}

运行结果：

如果需要关注子节点的变化：

package com.zookeeper;

import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;

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

public class GetChildSync {

    private static ZooKeeper zooKeeper;

    public static void main(String[] args) {
        try {
            zooKeeper = new ZooKeeper("192.168.40.135:2181", 5000, new Watcher() {
                public void process(WatchedEvent watchedEvent) {
                    if (watchedEvent.getState() == Event.KeeperState.SyncConnected) {
                        if (watchedEvent.getType() == Event.EventType.None && null == watchedEvent.getPath()) {
                            doSomeThing();
                        } else {
                            if (watchedEvent.getType() == Event.EventType.NodeChildrenChanged) {
                                try {
                                    System.out.println(zooKeeper.getChildren(watchedEvent.getPath(), true));
                                }
                                catch (KeeperException e) {
                                    e.printStackTrace();
                                }
                                catch (InterruptedException e) {
                                    e.printStackTrace();
                                }
                            }
                        }

                    }
                }
            });
            System.out.println("state:{}" + zooKeeper.getState());
            Thread.sleep(Integer.MAX_VALUE);
        }
        catch (IOException e) {
            System.out.println("connect zk failed");
        }
        catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    private static void doSomeThing() {
        List<String> children = null;
        try {
            //false表示不需要需要关注子节点的变化
            children = zooKeeper.getChildren("/", true);
        }
        catch (KeeperException e) {
            e.printStackTrace();
        }
        catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("children:" + children);
    }
}

运行结果：

通过服务端给根节点添加一个子节点，就会打印出来：

异步获取：

package com.zookeeper;

import org.apache.zookeeper.AsyncCallback;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.Stat;

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

public class GetChildASync {

    private static ZooKeeper zooKeeper;

    public static void main(String[] args) {
        try {
            zooKeeper = new ZooKeeper("192.168.40.135:2181", 5000, new Watcher() {
                public void process(WatchedEvent watchedEvent) {
                    if (watchedEvent.getState() == Event.KeeperState.SyncConnected) {
                        if (watchedEvent.getType() == Event.EventType.None && null == watchedEvent.getPath()) {
                            doSomeThing();
                        } else {
                            if (watchedEvent.getType() == Event.EventType.NodeChildrenChanged) {
                                zooKeeper.getChildren(watchedEvent.getPath(), true, new ChildrenClallBack(), "异步获取");
                            }
                        }

                    }
                }
            });
            System.out.println("state:{}" + zooKeeper.getState());
            Thread.sleep(Integer.MAX_VALUE);
        }
        catch (IOException e) {
            System.out.println("connect zk failed");
        }
        catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    static class ChildrenClallBack implements AsyncCallback.Children2Callback {
        /**
         *
         * @param rc  返回码，如果异步创建成功，返回0
         * @param path  创建节点的完整路径
         * @param ctx  异步调用的上下文，。。也就是上面传下来的“异步获取”字符串
         * @param children
         * @param stat
         */
        public void processResult(int rc, String path, Object ctx, List<String> children, Stat stat) {
            StringBuilder stringBuilder = new StringBuilder();
            stringBuilder.append("rc=" + rc).append("\n");
            stringBuilder.append("path=" + path).append("\n");
            stringBuilder.append("ctx=" + ctx).append("\n");
            stringBuilder.append("children=" + children).append("\n");
            stringBuilder.append("stat=" + stat).append("\n");
            System.out.println(stringBuilder.toString());
        }
    }
    private static void doSomeThing() {
        //false表示不需要需要关注子节点的变化
        zooKeeper.getChildren("/", true, new ChildrenClallBack(), "异步获取");
    }
}

运行结果：

同步获取节点数据：

package com.zookeeper;

import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.Stat;

import java.io.IOException;

public class GetDataSync {

    private static ZooKeeper zooKeeper;
    private static Stat stat = new Stat();

    public static void main(String[] args) {
        try {
            zooKeeper = new ZooKeeper("192.168.40.135:2181", 5000, new Watcher() {
                public void process(WatchedEvent watchedEvent) {
                    if (watchedEvent.getState() == Event.KeeperState.SyncConnected) {
                        if (watchedEvent.getType() == Event.EventType.None && null == watchedEvent.getPath()) {
                            doSomeThing();
                        } else {
                            if (watchedEvent.getType() == Event.EventType.NodeDataChanged) {
                                try {
                                    System.out.println(new String(zooKeeper.getData(watchedEvent.getPath(), true, stat)));
                                }
                                catch (KeeperException e) {
                                    e.printStackTrace();
                                }
                                catch (InterruptedException e) {
                                    e.printStackTrace();
                                }
                            }
                        }

                    }
                }
            });
            System.out.println("state:{}" + zooKeeper.getState());
            Thread.sleep(Integer.MAX_VALUE);
        }
        catch (IOException e) {
            System.out.println("connect zk failed");
        }
        catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    private static void doSomeThing() {
        byte[] data = null;
        try {
            //false表示不需要需要关注子节点的变化
            data = zooKeeper.getData("/node_5", true, stat);
        }
        catch (KeeperException e) {
            e.printStackTrace();
        }
        catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("data:" + new String(data));
        System.out.println("stat:" + stat);
    }
}

运行结果：

异步获取节点数据：

package com.zookeeper;

import org.apache.zookeeper.AsyncCallback;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.Stat;

import java.io.IOException;

public class GetDataASync {

    private static ZooKeeper zooKeeper;

    public static void main(String[] args) {
        try {
            zooKeeper = new ZooKeeper("192.168.40.135:2181", 5000, new Watcher() {
                public void process(WatchedEvent watchedEvent) {
                    if (watchedEvent.getState() == Event.KeeperState.SyncConnected) {
                        if (watchedEvent.getType() == Event.EventType.None && null == watchedEvent.getPath()) {
                            doSomeThing();
                        } else {
                            if (watchedEvent.getType() == Event.EventType.NodeDataChanged) {
                                zooKeeper.getData(watchedEvent.getPath(), true, new DataClallBack(), "异步获取节点数据");
                            }
                        }

                    }
                }
            });
            Thread.sleep(Integer.MAX_VALUE);
        }
        catch (IOException e) {
            System.out.println("connect zk failed");
        }
        catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
    static class DataClallBack implements AsyncCallback.DataCallback {

        public void processResult(int rc, String path, Object ctx, byte[] bytes, Stat stat) {
            StringBuilder stringBuilder = new StringBuilder();
            stringBuilder.append("rc=" + rc).append("\n");
            stringBuilder.append("path=" + path).append("\n");
            stringBuilder.append("ctx=" + ctx).append("\n");
            stringBuilder.append("bytes=" + new String(bytes)).append("\n");
            stringBuilder.append("stat=" + stat).append("\n");
            System.out.println(stringBuilder.toString());
        }
    }

    private static void doSomeThing() {
        //false表示不需要需要关注子节点的变化
        zooKeeper.getData("/node_5", true, new DataClallBack(), "异步获取节点数据");
    }
}