分布式服务管理zookeeper的java api

zookeeper是一个分布式服务管理工具，本身具备高可用性，很多知名分布式系统入hadoop、Hbase等都采用zk管理。

常见的两个应用场景：1、服务的注册与发现　　2、集群统一配置

下面看一下使用java 对zk进行交互的常用api

首先maven引入：

<dependency>
    <groupId>org.apache.zookeeper</groupId>
    <artifactId>zookeeper</artifactId>
    <version>3.5.3-beta</version>
</dependency>
<dependency>
    <groupId>com.github.sgroschupf</groupId>
    <artifactId>zkclient</artifactId>
    <version>0.1</version>
</dependency>

import org.I0Itec.zkclient.ZkClient;
import org.I0Itec.zkclient.serialize.SerializableSerializer;
import org.apache.zookeeper.CreateMode;

/**
 * @author panteng
 * @description
 * @date 17-5-24.
 */
public class Zk {
    public static void main(String[] arges) {
        String ZKServers = "10.38.164.80:2181,10.38.164.80:2182,10.38.164.80:2183";
        /**
         * 创建会话
         * new SerializableSerializer() 创建序列化器接口，用来序列化和反序列化
         */
        ZkClient zkClient = new ZkClient(ZKServers, 10000, 10000, new SerializableSerializer());
        System.out.println("conneted ok!");

        //订阅节点的子节点变化
        zkClient.subscribeChildChanges("/javaApp", new ZKChildListener());
        String appPath = zkClient.create("/javaApp/api", "javaApp", CreateMode.EPHEMERAL_SEQUENTIAL);
        //输出创建节点的路径
        System.out.println("created path:" + appPath);
        //订阅数据的变化
        zkClient.subscribeDataChanges(appPath, new ZkDataListener());

        //读数据
        String str = zkClient.readData(appPath);
        System.out.println(str);
        //写数据
        zkClient.writeData(appPath, "newJavaApp");
        System.out.println(zkClient.readData(appPath));
        //判断节点是否存在
        System.out.println(zkClient.exists("/javaApp/api0000000010"));

        try {
            Thread.sleep(20000);
        } catch (Exception e) {

        }
    }
}

import org.I0Itec.zkclient.IZkDataListener;

/**
 * @author panteng
 * @description
 * @date 17-5-24.
 */
public class ZkDataListener implements IZkDataListener {
    /**
     * 节点数据发生变化时 触发此函数
     *
     * @param s 发生变化的节点路径
     * @param o 节点变化后的数据
     * @throws Exception
     */
    @Override
    public void handleDataChange(String s, Object o) throws Exception {
        System.out.println("Change = " + s + "  obj=" + o);
    }

    @Override
    public void handleDataDeleted(String s) throws Exception {
        System.out.println("Delete = " + s);
    }
}

import org.I0Itec.zkclient.IZkDataListener;

/**
 * @author panteng
 * @description
 * @date 17-5-24.
 */
public class ZkDataListener implements IZkDataListener {
    /**
     * 节点数据发生变化时 触发此函数
     *
     * @param s 发生变化的节点路径
     * @param o 节点变化后的数据
     * @throws Exception
     */
    @Override
    public void handleDataChange(String s, Object o) throws Exception {
        System.out.println("Change = " + s + "  obj=" + o);
    }

    @Override
    public void handleDataDeleted(String s) throws Exception {
        System.out.println("Delete = " + s);
    }
}

遍历所有节点

public static void getAllNodes(ZkClient zkClient, String currentPath) {
        try {
            List<String> stringList = zkClient.getChildren(currentPath);
            for (String str : stringList) {
                if ("/".equals(currentPath)) {
                    str = currentPath + str;
                } else {
                    str = currentPath + "/" + str;
                }
                System.out.println(str);
                getAllNodes(zkClient, str);
            }
        } catch (Exception e) {
            if (e.getMessage().indexOf("KeeperErrorCode = NoNode for") > -1) {
                return;
            }
        }

    }