zookeeper的Java API

原生api

maven引入

        <dependency>
            <groupId>org.apache.zookeeper</groupId>
            <artifactId>zookeeper</artifactId>
            <version>3.4.8</version>
        </dependency>

package zookeeper;

import org.apache.zookeeper.*;
import org.apache.zookeeper.data.Stat;
import java.util.List;
import java.io.IOException;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;

public class CreateNodeDemo implements Watcher {
    private final static String CONNECT_STRING = "192.168.36.128:2181,192.168.36.129:2181,192.168.36.130:2181";
    private static CountDownLatch countDownLatch = new CountDownLatch(1);
    private static ZooKeeper zookeeper;
    private static Stat stat = new Stat();

    public static void main(String[] args) throws IOException, InterruptedException, KeeperException {
        zookeeper = new ZooKeeper(CONNECT_STRING, 5000, new CreateNodeDemo());
        countDownLatch.await();
        System.out.println(zookeeper.getState());
        String result = zookeeper.create("/node1", "123".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
        zookeeper.getData("/node1", new CreateNodeDemo(), stat);//添加监听

        //修改数据
        zookeeper.setData("/node1", "node123".getBytes(), -1);//-1是不管版本号
        Thread.sleep(2000);
        System.out.println(result);
        zookeeper.setData("/node1","345".getBytes(),-1);
        Thread.sleep(2000);
        //删除node
        zookeeper.delete("/del/del1",-1);
        Thread.sleep(2000);

        //创建子节点
        String path = "/nodes2";
        Stat st = zookeeper.exists(path,true);
        if(st==null){
            //节点不存在
            zookeeper.create(path, "123".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
            TimeUnit.SECONDS.sleep(1);
        }
        Stat st1 = zookeeper.exists(path+"/node1",true);
        if(st1==null){
            //节点不存在
            zookeeper.create(path+"/node1", "123".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
            TimeUnit.SECONDS.sleep(1);
        }
        TimeUnit.SECONDS.sleep(1);

        //修改子路径
        zookeeper.setData(path+"/node1","mic123".getBytes(),-1);
        TimeUnit.SECONDS.sleep(1);
        //获取子节点
        List<String> children = zookeeper.getChildren("nod/e",true);
    }

    public void process(WatchedEvent watchedEvent) {
        if (watchedEvent.getState() == Event.KeeperState.SyncConnected) {
            if(Event.EventType.None==watchedEvent.getType()&&watchedEvent.getPath()==null){
                countDownLatch.countDown();
                System.out.println(watchedEvent.getType()+"-----"+watchedEvent.getPath());
            }else if (watchedEvent.getType() == Event.EventType.NodeDataChanged) {
                try {
                    System.out.println("路径" + watchedEvent.getPath() + "-->数据变更：" + zookeeper.getData(watchedEvent.getPath(), true, stat));
                } catch (KeeperException e) {
                    e.printStackTrace();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            } else if (watchedEvent.getType() == Event.EventType.NodeChildrenChanged) {
                try {
                    System.out.println("路径" + watchedEvent.getPath() + "-->子节点变更：" + zookeeper.getData(watchedEvent.getPath(), true, stat));
                } catch (KeeperException e) {
                    e.printStackTrace();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            } else if (watchedEvent.getType() == Event.EventType.NodeCreated) {
                try {
                    System.out.println("路径" + watchedEvent.getPath() + "-->节点创建：" + zookeeper.getData(watchedEvent.getPath(), true, stat));
                } catch (KeeperException e) {
                    e.printStackTrace();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            } else if (watchedEvent.getType() == Event.EventType.NodeDeleted) {
                try {
                    System.out.println("路径" + watchedEvent.getPath() + "-->节点删除：" + zookeeper.getData(watchedEvent.getPath(), true, stat));
                } catch (KeeperException e) {
                    e.printStackTrace();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
        System.out.println(watchedEvent.getType());
    }
}

权限控制

权限控制模式有：

schema：授权对象
ip ：ip
Digest：账号、密码
world ：开放式的权限控制模式，数据节点的访问权限对所有用户开放。
super：超级用户，可以对zookeeper上的数据节点进行操作

连接状态

KeeperStat.Expired：在一定时间内客户端没有收到服务器的通知，则认为当前回话已经过期
KeeperStat.Disconnected：断开连接的状态
KeeperStat.SyncConnected：客户端与服务器在某一个节点上建立连接，并完成一次version、zxid同步
KeeperStat.authFailed：授权失败

事件类型

NodeCreated：节点创建时触发
NodeChildrenChanged：子节点创建、删除、数据发生变化时触发
NodeDataChanged：节点数据发生变化触发
NodeDeleted：节点删除触发
None：客户端与服务器连接状态发生改变时触发

zkclient

ZkClient是基于zookeeper原生api进行封装的框架，简化了一定的操作。但是最常用的还是下面的Curator。

<dependency>
    <groupId>com.101tec</groupId>
    <artifactId>zkclient</artifactId>
    <version>0.10</version>
</dependency>

package zkClient;

import org.I0Itec.zkclient.IZkDataListener;
import org.I0Itec.zkclient.ZkClient;

public class ZkClientDemo {
    public static void main(String[] args) {
        ZkClient zkClient = new ZkClient("",5000);
        zkClient.createPersistent("");
        //递归创建
        zkClient.createPersistent("",true);
        //递归删除
        zkClient.deleteRecursive("");
        //修改
        zkClient.writeData("","data");
        //订阅节点信息
        zkClient.subscribeDataChanges("", new IZkDataListener() {
            public void handleDataChange(String s, Object o) throws Exception {

            }

            public void handleDataDeleted(String s) throws Exception {

            }
        });
    }
}

Curator

Curator是Netflix公司的开源zookeeper产品，Eureka也是这家公司的。Curator提供了各种应用场景的实现。
包括两个模块：
curator-framework
curator-recipes

<dependency>
    <groupId>org.apache.curator</groupId>
    <artifactId>curator-framework</artifactId>
    <version>2.11.0</version>
</dependency>
<dependency>
    <groupId>org.apache.curator</groupId>
    <artifactId>curator-recipes</artifactId>
    <version>2.11.0</version>
</dependency>