尚硅谷大数据技术之Zookeeper 第4章 Zookeeper实战

4.1 分布式安装部署

0)集群规划

在hadoop102、hadoop103和hadoop104三个节点上部署Zookeeper。

1)解压安装

(1)解压zookeeper安装包到/opt/module/目录下

[atguigu@hadoop102 software]$ tar -zxvf zookeeper-3.4.10.tar.gz -C /opt/module/

(2)在/opt/module/zookeeper-3.4.10/这个目录下创建zkData

mkdir -p zkData

(3)重命名/opt/module/zookeeper-3.4.10/conf这个目录下的zoo_sample.cfg为zoo.cfg

mv zoo_sample.cfg zoo.cfg

2)配置zoo.cfg文件

(1)具体配置

dataDir=/opt/module/zookeeper-3.4.10/zkData

增加如下配置

#######################cluster##########################

server.2=hadoop102:2888:3888

server.3=hadoop103:2888:3888

server.4=hadoop104:2888:3888

(2)配置参数解读

Server.A=B:C:D。

A是一个数字,表示这个是第几号服务器;

B是这个服务器的ip地址;

C是这个服务器与集群中的Leader服务器交换信息的端口;

D是万一集群中的Leader服务器挂了,需要一个端口来重新进行选举,选出一个新的Leader,而这个端口就是用来执行选举时服务器相互通信的端口。

集群模式下配置一个文件myid,这个文件在dataDir目录下,这个文件里面有一个数据就是A的值,Zookeeper启动时读取此文件,拿到里面的数据与zoo.cfg里面的配置信息比较从而判断到底是哪个server。

3)集群操作

(1)在/opt/module/zookeeper-3.4.10/zkData目录下创建一个myid的文件

touch myid

添加myid文件,注意一定要在linux里面创建,在notepad++里面很可能乱码

(2)编辑myid文件

vi myid

在文件中添加与server对应的编号:如2

(3)拷贝配置好的zookeeper到其他机器上

scp -r zookeeper-3.4.10/ root@hadoop103.atguigu.com:/opt/app/

scp -r zookeeper-3.4.10/ root@hadoop104.atguigu.com:/opt/app/

并分别修改myid文件中内容为3、4

(4)分别启动zookeeper

[root@hadoop102 zookeeper-3.4.10]# bin/zkServer.sh start

[root@hadoop103 zookeeper-3.4.10]# bin/zkServer.sh start

[root@hadoop104 zookeeper-3.4.10]# bin/zkServer.sh start

(5)查看状态

[root@hadoop102 zookeeper-3.4.10]# bin/zkServer.sh status

JMX enabled by default

Using config: /opt/module/zookeeper-3.4.10/bin/../conf/zoo.cfg

Mode: follower

[root@hadoop103 zookeeper-3.4.10]# bin/zkServer.sh status

JMX enabled by default

Using config: /opt/module/zookeeper-3.4.10/bin/../conf/zoo.cfg

Mode: leader

[root@hadoop104 zookeeper-3.4.5]# bin/zkServer.sh status

JMX enabled by default

Using config: /opt/module/zookeeper-3.4.10/bin/../conf/zoo.cfg

Mode: follower

4.2 客户端命令行操作

命令基本语法

功能描述

help

显示所有操作命令

ls path [watch]

使用 ls 命令来查看当前znode中所包含的内容

ls2 path [watch]

查看当前节点数据并能看到更新次数等数据

create

普通创建

-s  含有序列

-e  临时(重启或者超时消失)

get path [watch]

获得节点的值

set

设置节点的具体值

stat

查看节点状态

delete

删除节点

rmr

递归删除节点

1)启动客户端

[atguigu@hadoop103 zookeeper-3.4.10]$ bin/zkCli.sh

2)显示所有操作命令

[zk: localhost:2181(CONNECTED) 1] help

3)查看当前znode中所包含的内容

[zk: localhost:2181(CONNECTED) 0] ls /

[zookeeper]

4)查看当前节点数据并能看到更新次数等数据

[zk: localhost:2181(CONNECTED) 1] ls2 /

[zookeeper]

cZxid = 0x0

ctime = Thu Jan 01 08:00:00 CST 1970

mZxid = 0x0

mtime = Thu Jan 01 08:00:00 CST 1970

pZxid = 0x0

cversion = -1

dataVersion = 0

aclVersion = 0

ephemeralOwner = 0x0

dataLength = 0

numChildren = 1

5)创建普通节点

[zk: localhost:2181(CONNECTED) 2] create /app1 “hello app1”

Created /app1

[zk: localhost:2181(CONNECTED) 4] create /app1/server101 “192.168.1.101”

Created /app1/server101

6)获得节点的值

[zk: localhost:2181(CONNECTED) 6] get /app1

hello app1

cZxid = 0x20000000a

ctime = Mon Jul 17 16:08:35 CST 2017

mZxid = 0x20000000a

mtime = Mon Jul 17 16:08:35 CST 2017

pZxid = 0x20000000b

cversion = 1

dataVersion = 0

aclVersion = 0

ephemeralOwner = 0x0

dataLength = 10

numChildren = 1

[zk: localhost:2181(CONNECTED) 8] get /app1/server101

192.168.1.101

cZxid = 0x20000000b

ctime = Mon Jul 17 16:11:04 CST 2017

mZxid = 0x20000000b

mtime = Mon Jul 17 16:11:04 CST 2017

pZxid = 0x20000000b

cversion = 0

dataVersion = 0

aclVersion = 0

ephemeralOwner = 0x0

dataLength = 13

numChildren = 0

7)创建短暂节点

[zk: localhost:2181(CONNECTED) 9] create -e /app-emphemeral 8888

(1)在当前客户端是能查看到的

[zk: localhost:2181(CONNECTED) 10] ls /

[app1, app-emphemeral, zookeeper]

(2)退出当前客户端然后再重启客户端

[zk: localhost:2181(CONNECTED) 12] quit

[atguigu@hadoop104 zookeeper-3.4.10]$ bin/zkCli.sh

(3)再次查看根目录下短暂节点已经删除

[zk: localhost:2181(CONNECTED) 0] ls /

[app1, zookeeper]

8)创建带序号的节点

(1)先创建一个普通的根节点app2

[zk: localhost:2181(CONNECTED) 11] create /app2 “app2”

(2)创建带序号的节点

[zk: localhost:2181(CONNECTED) 13] create -s /app2/aa 888

Created /app2/aa0000000000

[zk: localhost:2181(CONNECTED) 14] create -s /app2/bb 888

Created /app2/bb0000000001

[zk: localhost:2181(CONNECTED) 15] create -s /app2/cc 888

Created /app2/cc0000000002

如果原节点下有1个节点,则再排序时从1开始,以此类推。

[zk: localhost:2181(CONNECTED) 16] create -s /app1/aa 888

Created /app1/aa0000000001

9)修改节点数据值

[zk: localhost:2181(CONNECTED) 2] set /app1 999

10)节点的值变化监听

(1)在104主机上注册监听/app1节点数据变化

[zk: localhost:2181(CONNECTED) 26] get /app1 watch

(2)在103主机上修改/app1节点的数据

[zk: localhost:2181(CONNECTED) 5] set /app1  777

(3)观察104主机收到数据变化的监听

WATCHER::

WatchedEvent state:SyncConnected type:NodeDataChanged path:/app1

11)节点的子节点变化监听(路径变化)

(1)在104主机上注册监听/app1节点的子节点变化

[zk: localhost:2181(CONNECTED) 1] ls /app1 watch

[aa0000000001, server101]

(2)在103主机/app1节点上创建子节点

[zk: localhost:2181(CONNECTED) 6] create /app1/bb 666

Created /app1/bb

(3)观察104主机收到子节点变化的监听

WATCHER::

WatchedEvent state:SyncConnected type:NodeChildrenChanged path:/app1

12)删除节点

[zk: localhost:2181(CONNECTED) 4] delete /app1/bb

13)递归删除节点

[zk: localhost:2181(CONNECTED) 7] rmr /app2

14)查看节点状态

[zk: localhost:2181(CONNECTED) 12] stat /app1

cZxid = 0x20000000a

ctime = Mon Jul 17 16:08:35 CST 2017

mZxid = 0x200000018

mtime = Mon Jul 17 16:54:38 CST 2017

pZxid = 0x20000001c

cversion = 4

dataVersion = 2

aclVersion = 0

ephemeralOwner = 0x0

dataLength = 3

numChildren = 2

4.3 API应用

4.3.1 eclipse环境搭建

1)创建一个Maven工程

2)添加pom文件

<dependencies>

<dependency>

<groupId>junit</groupId>

<artifactId>junit</artifactId>

<version>RELEASE</version>

</dependency>

<dependency>

<groupId>org.apache.logging.log4j</groupId>

<artifactId>log4j-core</artifactId>

<version>2.8.2</version>

</dependency>

<!– https://mvnrepository.com/artifact/org.apache.zookeeper/zookeeper –>

<dependency>

<groupId>org.apache.zookeeper</groupId>

<artifactId>zookeeper</artifactId>

<version>3.4.10</version>

</dependency>

</dependencies>

3)拷贝log4j.properties文件到项目根目录

4.3.2 创建ZooKeeper客户端

 

private static String connectString = “hadoop102:2181,hadoop103:2181,hadoop104:2181”;

private static int sessionTimeout = 2000;

private ZooKeeper zkClient = null;

 

@Before

public void init() throws Exception {

 

zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {

@Override

public void process(WatchedEvent event) {

// 收到事件通知后的回调函数(用户的业务逻辑)

System.out.println(event.getType() + “–” + event.getPath());

 

// 再次启动监听

try {

zkClient.getChildren(“/”, true);

} catch (Exception e) {

e.printStackTrace();

}

}

});

}

4.3.3 创建子节点

// 创建子节点

@Test

public void create() throws Exception {

// 数据的增删改查

// 参数1:要创建的节点的路径; 参数2:节点数据 ; 参数3:节点权限 ;参数4:节点的类型

String nodeCreated = zkClient.create(“/eclipse”, “hello zk”.getBytes(), Ids.OPEN_ACL_UNSAFE,CreateMode.PERSISTENT);

}

4.3.4 获取子节点监听

// 获取子节点

@Test

public void getChildren() throws Exception {

List<String> children = zkClient.getChildren(“/”, true);

 

for (String child : children) {

System.out.println(child);

}

 

// 延时阻塞

Thread.sleep(Long.MAX_VALUE);

}

4.3.5 判断znode是否存在

// 判断znode是否存在

@Test

public void exist() throws Exception {

Stat stat = zkClient.exists(“/eclipse”, false);

 

System.out.println(stat == null ? “not exist” : “exist”);

}

 

4.4 案例实战

监听服务器节点动态上下线案例

1)需求:某分布式系统中,主节点可以有多台,可以动态上下线,任意一台客户端都能实时感知到主节点服务器的上下线

2)需求分析

3)具体实现:

(0)现在集群上创建/servers节点

[zk: localhost:2181(CONNECTED) 10] create /servers “servers”

Created /servers

(1)服务器端代码

package com.atguigu.zkcase;

import java.io.IOException;

import org.apache.zookeeper.CreateMode;

import org.apache.zookeeper.WatchedEvent;

import org.apache.zookeeper.Watcher;

import org.apache.zookeeper.ZooKeeper;

import org.apache.zookeeper.ZooDefs.Ids;

 

public class DistributeServer {

private static String connectString = “hadoop102:2181,hadoop103:2181,hadoop104:2181”;

private static int sessionTimeout = 2000;

private ZooKeeper zk = null;

private String parentNode = “/servers”;

// 创建到zk的客户端连接

public void getConnect() throws IOException{

zk = new ZooKeeper(connectString, sessionTimeout, new Watcher() {

 

@Override

public void process(WatchedEvent event) {

 

}

});

}

// 注册服务器

public void registServer(String hostname) throws Exception{

String create = zk.create(parentNode + “/server”, hostname.getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);

System.out.println(hostname +” is noline “+ create);

}

// 业务功能

public void business(String hostname) throws Exception{

System.out.println(hostname+” is working …”);

Thread.sleep(Long.MAX_VALUE);

}

public static void main(String[] args) throws Exception {

// 获取zk连接

DistributeServer server = new DistributeServer();

server.getConnect();

// 利用zk连接注册服务器信息

server.registServer(args[0]);

// 启动业务功能

server.business(args[0]);

}

}

(2)客户端代码

package com.atguigu.zkcase;

import java.io.IOException;

import java.util.ArrayList;

import java.util.List;

import org.apache.zookeeper.WatchedEvent;

import org.apache.zookeeper.Watcher;

import org.apache.zookeeper.ZooKeeper;

 

public class DistributeClient {

private static String connectString = “hadoop102:2181,hadoop103:2181,hadoop104:2181”;

private static int sessionTimeout = 2000;

private ZooKeeper zk = null;

private String parentNode = “/servers”;

private volatile ArrayList<String> serversList = new ArrayList<>();

 

// 创建到zk的客户端连接

public void getConnect() throws IOException {

zk = new ZooKeeper(connectString, sessionTimeout, new Watcher() {

 

@Override

public void process(WatchedEvent event) {

 

// 再次启动监听

try {

getServerList();

} catch (Exception e) {

e.printStackTrace();

}

}

});

}

 

//

public void getServerList() throws Exception {

// 获取服务器子节点信息,并且对父节点进行监听

List<String> children = zk.getChildren(parentNode, true);

ArrayList<String> servers = new ArrayList<>();

for (String child : children) {

byte[] data = zk.getData(parentNode + “/” + child, false, null);

 

servers.add(new String(data));

}

 

// 把servers赋值给成员serverList,已提供给各业务线程使用

serversList = servers;

 

System.out.println(serversList);

}

 

// 业务功能

public void business() throws Exception {

System.out.println(“client is working …”);

Thread.sleep(Long.MAX_VALUE);

}

 

public static void main(String[] args) throws Exception {

 

// 获取zk连接

DistributeClient client = new DistributeClient();

client.getConnect();

 

// 获取servers的子节点信息,从中获取服务器信息列表

client.getServerList();

 

// 业务进程启动

client.business();

}

}

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