zookeeper的安装与JavaAPI的使用

灰太狼 2022-09-30 06:46 150阅读 0赞

> 这一篇主要是介绍 zookeeper 开发环境的搭建以及客户端Java API的使用

# 1. zookeeper开发环境搭建 #

（1）首先要去官网下载安装包， 下面给出传送门：  
[http://mirror.bit.edu.cn/apache/zookeeper/stable/][http_mirror.bit.edu.cn_apache_zookeeper_stable]

下载之后解压，这里我是解压在 /opt/目录下：

$tar -zxvf zookeeper-3.4.9.tar,gz

（2）解压之后就是要配置环境变量：  
我是子啊Mac 下，所以是 ~/.bash\_profile 文件中配置， 如果是Linux下的话，应该是在~/.bashrc 下配置

export ZOOKEEPER_HOME=/opt/zookeeper-3.4.9
    export PATH=$PATH:$ZOOKEEPER_HOME/bin

（3）配置了环境变量之后，就可以设置 zookeeper的配置文件了，默认是 zookeeper-3.4.9/conf/zoo.cfg 配置文件在zookeeper服务端在启动时被加载， 但是conf目录下并没有这个文件，所以我们直接把conf目录下的 zoo\_sample.cfg 复制成zoo.cfg 就OK，配置内容直接用默认的。

（4） 启动服务端：运行一下命令：

$zkServer.sh start

这时服务端就启动了，通过以下命令可以查看服务端是否启动成功：

￥echo ruok | nc localhost 2181

具体执行过程可以看下图：  
![这里写图片描述][SouthEast]

# 2. Java API的使用 #

对于zookeeper 的客户端连接， zookeeper 提供了一套 Java API来进行连接调用。

具体的详解这里就不给出了，直接给出具体的代码：

### 客户端连接回调的观察者ConnectionWatcher.java ###

package com.zookeeper.lyt;
    
    import org.apache.zookeeper.*;
    
    import java.util.concurrent.CountDownLatch;
    
    /** * Created by louyuting on 2017/3/18. * 在 Zookeeper 中新建组 : /zoo */
    public class ConnectionWatcher implements Watcher{ 
    
        private static final int SESSION_TIMEOUT = 5000;
    
        protected ZooKeeper zk;
        private CountDownLatch connectedSignal = new CountDownLatch(1);
    
        public void connect(String hosts) throws Exception{
            //传入: 主机地址; 会话超时参数; Watcher对象,用于接收来自zookeeper的回调,获得各种事件的通知.
            //内部会创建一个线程连接到服务器;
            zk = new ZooKeeper(hosts, SESSION_TIMEOUT, this);
            //等待连接成功的响应.
            connectedSignal.await();
        }
    
        // override
        // 当客户端与服务端建立成功之后, watcher 的 process()方法会被调用. 参数是一个用于表示该连接的事件.
        public void process(WatchedEvent watchedEvent) {
            //返回响应, 表示连接已经成功
            if(watchedEvent.getState() == Event.KeeperState.SyncConnected){
                connectedSignal.countDown();
            }
        }
    
        /** * 创建一个新的 Zookeeper 的 znode, * @param groupName * @throws Exception */
        public void create(String groupName) throws Exception{
            String path = "/" + groupName;
    
            String createdPath = zk.create(path, null, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
    
            System.out.println("created " + createdPath);
        }
    
        public void close() throws Exception{
            zk.close();
        }
    }

### 创建组 CreateGroup.java ###

package com.zookeeper.lyt;
    
    import org.apache.zookeeper.*;
    
    import java.util.concurrent.CountDownLatch;
    
    /** * Created by louyuting on 2017/3/18. * 在 Zookeeper 中新建组 : /zoo */
    public class CreateGroup implements Watcher{ 
    
        private static final int SESSION_TIMEOUT = 5000;
    
        private ZooKeeper zk;
        private CountDownLatch connectedSignal = new CountDownLatch(1);
    
        public void connect(String hosts) throws Exception{
            //传入: 主机地址; 会话超时参数; Watcher对象,用于接收来自zookeeper的回调,获得各种事件的通知.
            //内部会创建一个线程连接到服务器;
            zk = new ZooKeeper(hosts, SESSION_TIMEOUT, this);
            //等待连接成功的响应.
            connectedSignal.await();
        }
    
        // override
        // 当客户端与服务端建立成功之后, watcher 的 process()方法会被调用. 参数是一个用于表示该连接的事件.
        public void process(WatchedEvent watchedEvent) {
            //返回响应, 表示连接已经成功
            if(watchedEvent.getState() == Event.KeeperState.SyncConnected){
                connectedSignal.countDown();
            }
        }
    
        /** * 创建一个新的 Zookeeper 的 znode, * @param groupName * @throws Exception */
        public void create(String groupName) throws Exception{
            String path = "/" + groupName;
    
            String createdPath = zk.create(path, null, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
    
            System.out.println("created " + createdPath);
        }
    
        public void close() throws Exception{
            zk.close();
        }
    
        // main
        public static void main(String[] args) throws Exception {
            CreateGroup createGroup = new CreateGroup();
            createGroup.connect("ip:port");
            createGroup.create("zoo");
            createGroup.close();
        }
    }

### 加入组 JoinGroup.java ###

package com.zookeeper.lyt;
    
    import org.apache.zookeeper.CreateMode;
    import org.apache.zookeeper.ZooDefs;
    
    import java.util.concurrent.TimeUnit;
    
    /** * Created by louyuting on 2017/3/18. * 加入组 */
    public class JoinGroup extends ConnectionWatcher { 
    
    
        public void join(String groupName, String menberName) throws Exception{
    
            String path = "/" + groupName + "/" + menberName;
    
            String createdPath = zk.create(path, null, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
    
            System.out.println("created " + createdPath);
        }
    
    
        public static void main(String[] args) throws Exception {
            JoinGroup joinGroup = new JoinGroup();
    
            joinGroup.connect("ip:port");
            joinGroup.join("zoo", "cow");
            TimeUnit.MICROSECONDS.sleep(Long.MAX_VALUE);
        }
    }

### 列出组：ListGroup.java ###

package com.zookeeper.lyt;
    
    import org.apache.zookeeper.KeeperException;
    
    import java.util.List;
    
    /** * Created by louyuting on 2017/3/18. * * 列出组成员 */
    public class ListGroup extends ConnectionWatcher { 
    
    
        public void list(String groupName) throws Exception{
    
            String path = "/" + groupName;
    
            try {
                List<String> children= zk.getChildren(path, false);
    
                if(children.isEmpty()){
                    System.out.println( path + " is empty");
                    System.exit(1);
                }else {
                    for (String child : children){
                        System.out.println(child);
                    }
                }
            } catch (KeeperException e) {
                e.printStackTrace();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    
    
        public static void main(String[] args) throws Exception {
            ListGroup listGroup = new ListGroup();
    
            listGroup.connect("ip:port");
            listGroup.list("zoo");
            listGroup.close();
        }
    }

### 删除组 DeleteGroup.java ###

package com.zookeeper.lyt;
    
    import org.apache.zookeeper.KeeperException;
    
    import java.util.List;
    
    /** * Created by louyuting on 2017/3/18. * * 列出组成员 */
    public class DeleteGroup extends ConnectionWatcher { 
    
    
        public void delete(String groupName) throws Exception{
    
            String path = "/" + groupName;
    
            try {
                List<String> children= zk.getChildren(path, false);
    
                for (String child : children){
                    zk.delete(path + "/" + child, -1);
                }
                zk.delete(path, -1);
            } catch (KeeperException.NoNodeException e) {
                e.printStackTrace();
                System.out.println(groupName + " is not existed");
                System.exit(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    
    
        public static void main(String[] args) throws Exception {
            DeleteGroup deleteGroup = new DeleteGroup();
    
            deleteGroup.connect("ip:port");
            deleteGroup.delete("zoo");
    
            deleteGroup.close();
        }
    }

[http_mirror.bit.edu.cn_apache_zookeeper_stable]: http://mirror.bit.edu.cn/apache/zookeeper/stable/
[SouthEast]: /images/20220708/109e7023d15e4dc8845c351f5706b6ba.png