zookeeper和java

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墨韵流香 2024-10-31 09:38:06

文章标签 zookeeper和java apache System zookeeper 文章分类 Java 后端开发

ZK

zk需要半数以上的节点存货才能对外提供服务！

安装

下载压缩包后，直接上传
使用tar -zxvf 解压
在目录下创建data文件夹，zk以后数据存在这里
cd到conf下，cp zoo_simle.conf zoo.cfg
vim zoo.cfg
修改 dataDir=/opt/zk/apache-zookeeper-3.7.0-bin/data
bin下面就可以./zkServer.sh start 启动
./zkServer.sh status 查看状态
./zkServer.sh stop 停止
jps查看进程
./zkCli.sh
进去后quit退出

不同服务器之间

主机:10.17.4.179
10.17.4.174
10.17.4.211
10.17.4.121

搭建环境后需要在data下
touch myid
然后给每个服务器编号！
每个机器一定要唯一（比如我3台机器对应1 2 3）
增加如下配置：
(server后面的值和对应myid我们写的什么这里就得写什么)
server.A=B:C:D A是一个数字，代表这是第几号服务器 B是服务器ip地址 C是服务器与集群中Leader服务器交换信息的端口 D是万亿集群中Leader服务器挂了，需要一个端口重新选举，选出新的leader增加配置在这里： server.1=10.17.4.174:2888:3888 server.2=10.17.4.211:2888:3888 server.3=10.17.4.121:2888:3888 server.1=192.168.2.84:2888:3888 server.2=192.168.2.85:2888:3888 server.3=192.168.2.86:2888:3888
然后分别启动zk
./zkServer.sh start 3台都是
启动后，通过 ./zkServer.sh status查看
（如果没有成功，那么可能是防火墙没关，要记住，所有zk节点的防火墙都要关，具体日志在logs下面zookeeper-root-..文件下看！）
sudo systemctl stop firewalld #临时关闭 sudo systemctl disable firewalld #然后reboot 永久关闭 sudo systemctl status firewalld #查看防火墙状态。
通过./zkCli.sh 连接客户端操作
使用help查看所有命令
create参数后
-e 短暂的节点 -s 顺序节点
修改使用set指令
退出客户端使用quit
监听节点变化
addWatch /node1
这样当/node1下面有任何发生变化时就会通知watch的客户端
Watch注册一次，只生效一次后就失效

ZK写数据的流程

客户端向zk其中一个节点发送写请求
如果该节点不是leader，那么将请求转发给leader,由leader广播给各个节点进行写入操作
当leader收到了大多数server数据写成功了，那么就认为成功了，这时leader通知这个节点写入成功，这个节点再通知客户端！

zookeeper和java_zookeeper和java

ZK使用java操作

<dependencies>
        <dependency>
            <groupId>org.apache.zookeeper</groupId>
            <artifactId>zookeeper</artifactId>
            <version>3.7.0</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
    </dependencies>
log4j.properties
### 设置###
log4j.rootLogger = debug,stdout,D,E
### 输出信息到控制抬 ###
log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Threshold = INFO
log4j.appender.stdout.Target = System.out
log4j.appender.stdout.layout = org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern = [%-5p] %d{yyyy-MM-dd HH:mm:ss,SSS} method:%l%n%m%n
### 输出DEBUG 级别以上的日志到=E://logs/error.log ###
log4j.appender.D = org.apache.log4j.DailyRollingFileAppender
log4j.appender.D.File = E://logs/log.log
log4j.appender.D.Append = true
log4j.appender.D.Encoding=UTF8
log4j.appender.D.Threshold = DEBUG
log4j.appender.D.layout = org.apache.log4j.PatternLayout
log4j.appender.D.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss}  - [ %p ]  %l %c %t - %m %n 
### 输出ERROR 级别以上的日志到=E://logs/error.log ###
log4j.appender.E = org.apache.log4j.DailyRollingFileAppender
log4j.appender.E.File =E://logs/error.log
log4j.appender.E.Append = true
log4j.appender.E.Encoding=UTF8
log4j.appender.E.Threshold = ERROR
log4j.appender.E.layout = org.apache.log4j.PatternLayout
log4j.appender.E.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss}  - [ %p ]  %l %c %t - %m %npackage com.zk.nxj;

import org.apache.zookeeper.*;
import org.apache.zookeeper.data.Stat;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.IOException;
import java.util.List;
import java.util.concurrent.TimeUnit;

/**
 * @author ningxinjie
 * @date 2021/4/1
 */
public class ZkTesst {
    private String connectString= "nxjvm01:2181,nxjvm02,192.168.2.86:2181"; // 我把ip已经配置到本机的hosts中了
    private int sessionTimeout = 2000; // 2s
    private ZooKeeper zkClient;

    // 创建客户端
    @Before
    public void init() throws IOException {
        System.out.println("===========================初始化中....=======================");
        zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
            @Override
            public void process(WatchedEvent watchedEvent) {
                System.out.println("你看到");
                System.out.println(watchedEvent.toString());
                System.out.println("的我");
            }
        });

    }

    @After
    public void close() throws InterruptedException {
        TimeUnit.SECONDS.sleep(8000); // 进程停止就没了
        System.out.println("========================关闭中....=======================");
        zkClient.close();
    }

    // 创建节点
    @Test
    public void testCreateNode() throws KeeperException, InterruptedException {
        //String path, byte[] data, List<ACL> acl, CreateMode createMode
        zkClient.create("/nxj", "美滋滋".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
    }

    // 获取子节并监听数据变化
    @Test
    public void getDataAndWatch() throws KeeperException, InterruptedException {

        List<String> children = zkClient.getChildren("/", true); // 这里设置为true就不需要手动写下方的方法啦！
        // zkClient.addWatch("/", AddWatchMode.PERSISTENT); // 手动显示增加监听
        children.forEach(System.out::println);
    }

    // 判断节点是否存在
    @Test
    public void judgeNodeExist() throws KeeperException, InterruptedException {
        Stat exists = zkClient.exists("/nxj", false);
        System.out.println(exists);
    }

}

服务器动态上下线感知案例

zookeeper和java_zookeeper_02

测试服务端代码：

package com.zk.nxj;

import org.apache.zookeeper.*;

import java.io.IOException;

/**
 * @author ningxinjie
 * @date 2021/4/1
 */
// 假装这是服务器了
public class DistributeServer {
    private String connectString = "nxjvm01:2181,nxjvm02,nxjvm03:2181"; // 我把ip已经配置到本机的hosts中了
    private int sessionTimeout = 2000; // 2s
    private ZooKeeper zkClient;

    public static void main(String[] args) throws Exception {
        DistributeServer server = new DistributeServer();
        // 1.连接zk集群
        server.getConnectZk();
        // 2.注册自己的ip
        server.register(args[0]);
        // 3.业务逻辑处理
        server.business();
    }

    private void getConnectZk() throws IOException {
        zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
            @Override
            public void process(WatchedEvent watchedEvent) {

            }
        });
    }

    private void register(String hostname) throws KeeperException, InterruptedException {
        // 创建一个临时且有顺序的
        String path = zkClient.create("/servers/server1", hostname.getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);
        System.out.println(hostname + "is online");
    }

    private void business() throws InterruptedException {
        Thread.sleep(Long.MAX_VALUE);
    }

}

测试客户端代码：

package com.zk.nxj;

import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

/**
 * @author ningxinjie
 * @date 2021/4/1
 */
public class DistributeClient {

    private String connectString= "nxjvm01:2181,nxjvm02,nxjvm03:2181"; // 我把ip已经配置到本机的hosts中了
    private int sessionTimeout = 2000; // 2s
    private ZooKeeper zkClient;
    List<String> serverHosts;

    public static void main (String[] args) throws Exception {
        DistributeClient client = new DistributeClient();
        // 1.获取连接
        client.getConnectZk();
        // 2.注册监听
        client.getHostsAndWatch();
        // 3.业务逻辑处理
        client.business();
    }

    private void getConnectZk() throws IOException {
        zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
            @Override
            public void process(WatchedEvent watchedEvent) {
                if (watchedEvent != null){
                    try {
                        System.out.println("服务端节点发生变化，新的列表为:");
                        getHostsAndWatch();
                    } catch (Exception e) {
                        System.out.println("获取列表出现异常");
                        e.printStackTrace();
                    }
                }
            }
        });
    }

    private void getHostsAndWatch() throws KeeperException, InterruptedException {
        List<String> children = zkClient.getChildren("/servers", true);
        serverHosts = new ArrayList<>();
        for (String node : children) {
            byte[] data = zkClient.getData("/servers/" + node, false, null);
            serverHosts.add(new String(data));
        }
        serverHosts.forEach(System.out::println);
        System.out.println("====");
    }

    private void business() throws InterruptedException {
        Thread.sleep(Long.MAX_VALUE);
    }
}