Hadoop生态圈-zookeeper的API用法详解

　　　　　　　　　　　　　　　　　　　　Hadoop生态圈-zookeeper的API用法详解

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　作者：尹正杰

版权声明：原创作品，谢绝转载！否则将追究法律责任。

一.测试前准备

1>.开启集群

[yinzhengjie@s101 ~]$ more `which xzk.sh`
#!/bin/bash
#@author :yinzhengjie
#blog:http://www.cnblogs.com/yinzhengjie
#EMAIL:y1053419035@qq.com

#判断用户是否传参
if [ $# -ne  ];then
    echo "无效参数，用法为: $0  {start|stop|restart|status}"
    exit
fi

#获取用户输入的命令
cmd=$

#定义函数功能
function zookeeperManger(){
    case $cmd in
    start)
        echo "启动服务"
        remoteExecution start
        ;;
    stop)
        echo "停止服务"
        remoteExecution stop
        ;;
    restart)
        echo "重启服务"
        remoteExecution restart
        ;;
    status)
        echo "查看状态"
        remoteExecution status
        ;;
    *)
        echo "无效参数，用法为: $0  {start|stop|restart|status}"
        ;;
    esac
}

#定义执行的命令
function remoteExecution(){
    for (( i= ; i<= ; i++ )) ; do
            tput setaf
            echo ========== s$i zkServer.sh  $ ================
            tput setaf
            ssh s$i  "source /etc/profile ; zkServer.sh $1"
    done
}

#调用函数
zookeeperManger
[yinzhengjie@s101 ~]$
[yinzhengjie@s101 ~]$ xzk.sh start
启动服务
========== s102 zkServer.sh start ================
ZooKeeper JMX enabled by default
Using config: /soft/zk/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED
========== s103 zkServer.sh start ================
ZooKeeper JMX enabled by default
Using config: /soft/zk/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED
========== s104 zkServer.sh start ================
ZooKeeper JMX enabled by default
Using config: /soft/zk/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED
[yinzhengjie@s101 ~]$ xcall.sh jps
============= s101 jps ============
 Jps
命令执行成功
============= s102 jps ============
 Jps
 QuorumPeerMain
命令执行成功
============= s103 jps ============
 Jps
 QuorumPeerMain
命令执行成功
============= s104 jps ============
 Jps
 QuorumPeerMain
命令执行成功
============= s105 jps ============
 Jps
命令执行成功
[yinzhengjie@s101 ~]$ 

[yinzhengjie@s101 ~]$ xzk.sh start

[yinzhengjie@s101 ~]$ start-dfs.sh
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/soft/hadoop-2.7./share/hadoop/common/lib/slf4j-log4j12-1.7..jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/soft/apache-hive-2.1.-bin/lib/log4j-slf4j-impl-2.4..jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.slf4j.impl.Log4jLoggerFactory]
Starting namenodes on [s101 s105]
s101: starting namenode, logging to /soft/hadoop-2.7./logs/hadoop-yinzhengjie-namenode-s101.out
s105: starting namenode, logging to /soft/hadoop-2.7./logs/hadoop-yinzhengjie-namenode-s105.out
s103: starting datanode, logging to /soft/hadoop-2.7./logs/hadoop-yinzhengjie-datanode-s103.out
s102: starting datanode, logging to /soft/hadoop-2.7./logs/hadoop-yinzhengjie-datanode-s102.out
s105: starting datanode, logging to /soft/hadoop-2.7./logs/hadoop-yinzhengjie-datanode-s105.out
s104: starting datanode, logging to /soft/hadoop-2.7./logs/hadoop-yinzhengjie-datanode-s104.out
Starting journal nodes [s102 s103 s104]
s102: starting journalnode, logging to /soft/hadoop-2.7./logs/hadoop-yinzhengjie-journalnode-s102.out
s103: starting journalnode, logging to /soft/hadoop-2.7./logs/hadoop-yinzhengjie-journalnode-s103.out
s104: starting journalnode, logging to /soft/hadoop-2.7./logs/hadoop-yinzhengjie-journalnode-s104.out
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/soft/hadoop-2.7./share/hadoop/common/lib/slf4j-log4j12-1.7..jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/soft/apache-hive-2.1.-bin/lib/log4j-slf4j-impl-2.4..jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.slf4j.impl.Log4jLoggerFactory]
Starting ZK Failover Controllers on NN hosts [s101 s105]
s101: starting zkfc, logging to /soft/hadoop-2.7./logs/hadoop-yinzhengjie-zkfc-s101.out
s105: starting zkfc, logging to /soft/hadoop-2.7./logs/hadoop-yinzhengjie-zkfc-s105.out
[yinzhengjie@s101 ~]$
[yinzhengjie@s101 ~]$ xcall.sh jps
============= s101 jps ============
Jps
DFSZKFailoverController
命令执行成功
============= s102 jps ============
Jps
DataNode
QuorumPeerMain
JournalNode
命令执行成功
============= s103 jps ============
DataNode
JournalNode
Jps
QuorumPeerMain
命令执行成功
============= s104 jps ============
JournalNode
Jps
DataNode
QuorumPeerMain
命令执行成功
============= s105 jps ============
DFSZKFailoverController
DataNode
Jps
命令执行成功
[yinzhengjie@s101 ~]$

[yinzhengjie@s101 ~]$ start-dfs.sh

2>.添加Maven依赖

 <?xml version="1.0" encoding="UTF-8"?>
 <project xmlns="http://maven.apache.org/POM/4.0.0"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <groupId>cn.org.yinzhengjie</groupId>
     <artifactId>MyZookeep</artifactId>
     <version>1.0-SNAPSHOT</version>

     <dependencies>
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
             <version>4.12</version>
         </dependency>

         <dependency>
             <groupId>org.apache.zookeeper</groupId>
             <artifactId>zookeeper</artifactId>
             <version>3.4.6</version>
         </dependency>
     </dependencies>
 </project>

二.Zookeeper的API常用方法介绍

1>.测试ls命令

 /*
 @author :yinzhengjie
 Blog:http://www.cnblogs.com/yinzhengjie/tag/Hadoop%E7%94%9F%E6%80%81%E5%9C%88/
 EMAIL:y1053419035@qq.com
 */
 package cn.org.yinzhengjie.zookeeper;

 import org.apache.zookeeper.ZooKeeper;
 import org.junit.Test;
 import java.util.List;

 public class ZookeeperDemo {
     /**
      * 测试ls
      */
     @Test
     public void testList() throws Exception {
         //定义连接服务器的URL，这些主机都在“C:\Windows\System32\drivers\etc\HOSTS”中做的有映射哟！
         String conn = "s102:2181,s103:2181,s104:2181";
         //实例化zk对象
         //参数一：连接串，指定zk客户端地址；参数二：超时时间，超过此时间未获得连接，抛出异常；参数三：指定watcher对象，我们指定为null即可
         ZooKeeper zk = new ZooKeeper(conn, 5000, null);
         //我们查看“/”节点下的数据
         List<String> children = zk.getChildren("/", null);
         //将查询的结果进行遍历
         for (String child : children) {
             System.out.println(child);
         }
     }
 }

　　以上代码输出结果如下：

2>.获取数据

 /*
 @author :yinzhengjie
 Blog:http://www.cnblogs.com/yinzhengjie/tag/Hadoop%E7%94%9F%E6%80%81%E5%9C%88/
 EMAIL:y1053419035@qq.com
 */
 package cn.org.yinzhengjie.zookeeper;

 import org.apache.zookeeper.ZooKeeper;
 import org.junit.Test;

 public class ZookeeperDemo {
     /**
      * 获取数据
      */
     @Test
     public void testGet() throws Exception {
         //定义连接服务器的URL，这些主机都在“C:\Windows\System32\drivers\etc\HOSTS”中做的有映射哟！
         String conn = "s102:2181,s103:2181,s104:2181";

         //实例化zk对象
         //参数一：连接串，指定zk客户端地址；参数二：超时时间，超过此时间未获得连接，抛出异常；参数三：指定watcher对象，我们指定为null即可
         ZooKeeper zk = new ZooKeeper(conn, 5000, null);
         byte[] data = zk.getData("/a", null, null);
         zk.close();
         System.out.println(new String(data));
     }
 }

　　以上代码输出结果如下：

3>.创建节点+数据

 /*
 @author :yinzhengjie
 Blog:http://www.cnblogs.com/yinzhengjie/tag/Hadoop%E7%94%9F%E6%80%81%E5%9C%88/
 EMAIL:y1053419035@qq.com
 */
 package cn.org.yinzhengjie.zookeeper;

 import org.apache.zookeeper.CreateMode;
 import org.apache.zookeeper.ZooDefs;
 import org.apache.zookeeper.ZooKeeper;
 import org.junit.Test;

 public class ZookeeperDemo {
     /**
      * 创建节点+数据
      */
     @Test
     public void testCreate() throws Exception {
         //定义连接服务器的URL，这些主机都在“C:\Windows\System32\drivers\etc\HOSTS”中做的有映射哟！
         String conn = "s102:2181,s103:2181,s104:2181";
         //实例化zk对象
         //参数一：连接串，指定zk客户端地址；参数二：超时时间，超过此时间未获得连接，抛出异常；参数三：指定watcher对象，我们指定为null即可
         ZooKeeper zk = new ZooKeeper(conn, 5000, null);
         //创建一个"/yzj"节点(该节点不能再zookeeper集群中存在，否则会抛异常哟)，并起名为“yinzhengjie”(写入的数据)。
         String s = zk.create("/yzj", "yinzhengjie".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
         System.out.println(s);
         zk.close();
     }
 }

　　以上代码输出结果如下：

4>.删除节点

 /*
 @author :yinzhengjie
 Blog:http://www.cnblogs.com/yinzhengjie/tag/Hadoop%E7%94%9F%E6%80%81%E5%9C%88/
 EMAIL:y1053419035@qq.com
 */
 package cn.org.yinzhengjie.zookeeper;

 import org.apache.zookeeper.ZooKeeper;
 import org.junit.Test;

 public class ZookeeperDemo {
     /**
      * 删除节点
      */
     @Test
     public void testDelete() throws Exception {
         String conn = "s102:2181,s103:2181,s104:2181";
         //实例化zk对象
         //param1：连接串，指定zk客户端地址；param2：超时时间，超过此时间未获得连接，抛出异常
         ZooKeeper zk = new ZooKeeper(conn, 5000, null);
         //删除zookeeper集群中的节点，删除的节点必须存在，如果不存在会抛异常哟（KeeperException$NoNodeException）
         zk.delete("/yzj",-1);
         zk.close();
     }
 }

5>.观察者模式，监控某个子节点小案例

 /*
 @author :yinzhengjie
 Blog:http://www.cnblogs.com/yinzhengjie/tag/Hadoop%E7%94%9F%E6%80%81%E5%9C%88/
 EMAIL:y1053419035@qq.com
 */
 package cn.org.yinzhengjie.zookeeper;

 import org.apache.zookeeper.WatchedEvent;
 import org.apache.zookeeper.Watcher;
 import org.apache.zookeeper.ZooKeeper;
 import org.junit.Test;

 public class ZookeeperDemo {
     /**
      * 观察者模式
      */
     @Test
     public void testWatch() throws Exception {
         String conn = "s102:2181,s103:2181,s104:2181";
         //实例化zk对象
         //param1：连接串，指定zk客户端地址；param2：超时时间，超过此时间未获得连接，抛出异常
         final ZooKeeper zk = new ZooKeeper(conn, 5000, null);
         /**
          * 通过回调机制，当监听的节点发生改变，会触发此机制，返回watcher中的方法
          *     触发之后，watcher结束
          */
         Watcher w = new Watcher() {
             public void process(WatchedEvent event) {
                 System.out.println(event.getPath()+"出事了: "+ event.getType());
                 try {
                     //用于监控"/a"节点下数据是否发生变化
                     zk.getChildren("/a", this, null);
                 } catch (Exception e) {
                     e.printStackTrace();
                 }
             }
         };
         zk.getChildren("/a", w, null);
         for ( ; ;){
             Thread.sleep(1000);
         }
     }
 }

　　以上代码执行结果如下：

6>.