zookeeper原生API操作（创建删除查询更改）zookeeper实战

目前主流有三种方法去操作zookeeper节点，即zookeeper shell、zookeeper原生API、apache curator API（在原生基础上封装，更加友好易用）。本文主要是基于zookeeper原生API来创建删除查询更改zookeeper节点。

注意事项：

• 原生zookeeper api创建某个节点，必须保证父节点已经存在，否则不能创建（即不能递归创建节点）
• 原生zookeeper api删除某个节点，如果该节点中还有子节点，则该父节点不能直接删除，而必须先删除所有子节点（即不能递归删除节点）

pom中添加如下依赖：

        
        
            org.apache.hadoop
            hadoop-common
            2.6.0-cdh5.7.0
        
        
            org.apache.zookeeper
            zookeeper
            3.4.6
        

java详细代码：

package com.example.zkaccess;

import org.apache.hadoop.conf.Configuration;
import org.apache.zookeeper.*;
import org.apache.zookeeper.data.Stat;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;

public class TestZk {
    
    // 初始化zookeeper client
    public ZooKeeper initZooKeeper(Configuration conf) {
        ZooKeeper zooKeeper = null;
        try {
            zooKeeper = new ZooKeeper(conf.get("ha.zookeeper.quorum"), 3000, new Watcher() {
            // conf.get("ha.zookeeper.quorum"): 读取hadoop配置项zookeeper quorum，即常说的connectstring
            // 可以配置在core-site.xml中，比如127.0.0.1:2181, 100.11.12.1:2181
            // 3000指timeout为3s
                @Override
                public void process(WatchedEvent event) {
                    System.out.println(event.toString());
                }
            });
        } catch (IOException e) {
            e.printStackTrace();
        }
        return zooKeeper;
    }


     // 创建父节点
     private void createParentNode(ZooKeeper client, String path) throws KeeperException, InterruptedException {
        String newPath = path;
        // 删除节点路径首尾的/符号
        if(path.startsWith("/")){
            newPath = newPath.substring(1);
        }
        if(path.endsWith("/")){
            newPath = newPath.substring(0,newPath.length()-1);
        }
         System.out.println(">>>>>> newPath is: " + newPath);
        String[] pathSplitArr = newPath.split("/");
        String subPath = "";
        // 逐级创建节点，pathSplitArr.length-1级（第pathSplitArr.length级是seq-node，这里不创建）
        for(int i=0;i>>>>> getNodeData newPath: " + newPath);       Stat stat = client.exists(newPath, false);
         System.out.println(stat==null ? ">>>>>> stat null":">>>>>> stat not null");
         if(stat != null){
             data = client.getData(newPath,false, stat);
         }
         return data;
     }



     // 修改节点数据
     public boolean setNodeData(ZooKeeper client, String path, byte[] data) {
        boolean finished = true;
         String newPath = path;
         if(!path.startsWith("/")){
             newPath = "/".concat(newPath);
         }
         if(path.endsWith("/")){
             newPath = newPath.substring(0, newPath.length()-1);
         }
        try {
             Stat stat = client.exists(newPath, false);
             // 节点存在才能够修改节点数据
             if( stat != null){
                 client.setData(newPath, data, stat.getVersion());
                 // 第3个参数：matched version，在此处为修改前的version，即stat.getVersion()
             }
         } catch (KeeperException e) {
             e.printStackTrace();
             finished = false;
         } catch (InterruptedException e) {
             e.printStackTrace();
             finished = false;
         }
         return finished;
     }


      // 删除节点
     public void deleteNode(ZooKeeper client, String path) throws KeeperException, InterruptedException {
         String newPath = path;
         if(!path.startsWith("/")){
             newPath = "/".concat(newPath);
         }
         if(path.endsWith("/")){
             newPath = newPath.substring(0, newPath.length()-1);
         }
        Stat stat = client.exists(newPath, false);
        // 先删除子节点
        if(stat != null){
            for(String node : client.getChildren(newPath, false)){
                // getChildren获取子节点名集合（不是全路径）
                System.out.println(">>>>>> node: " + node);
                Stat stat1 = client.exists(String.format("%s/%s", newPath, node),false);
                client.delete(String.format("%s/%s", newPath, node), stat1.getVersion());
            }
            // 再删除父节点
            client.delete(newPath, stat.getVersion());
        }
     }
     
}








package com.example.zkaccess;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.ZooKeeper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.Iterator;

/**
 * main类
 **/ 
public class TestMain {

    public static void main(String[] args) throws InterruptedException, KeeperException {

        // hadoop的配置类Configuration
        Configuration conf = new Configuration();
        String path = "/ns-1/tenant/mysql1/seq-/";
        String path1 = "/ns-1/tenant/mysql1/";
        TestZk testZk = new TestZk();
        // 初始化zookeeper client对象
        ZooKeeper zooKeeper = testZk.initZooKeeper(conf);
        // 创建顺序节点
        testZk.createSeqNode(zooKeeper, path1);
        System.out.println(new String(testZk.getNodeData(zooKeeper, path1), "UTF-8"));
        // 修改节点数据
        testZk.setNodeData(zooKeeper, path1, "test1".getBytes());
        System.out.println(new String(testZk.getNodeData(zooKeeper, path1), "UTF-8"));
        // 删除节点
        testZk.deleteNode(zooKeeper, path1);
        // 关闭zookeeper client
        zooKeeper.close();
    }

}