普通方式连接：org.apache.zookeeper zookeeper3.6.0
package com.example.demo01.service;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;
import java.util.concurrent.CountDownLatch;
public class test1 {
public static void main(String[] args) throws Exception {
//计数器对象（初始值为1）
CountDownLatch countDownLatch = new CountDownLatch(1);
//创建zookeeper连接对象（地址:端口,超时自动关闭时间,重写监视器接口）
ZooKeeper zookeeper = new ZooKeeper("192.168.17.119:2181", 3000, new Watcher() {
@Override
public void process(WatchedEvent event) {
//判断event.getState()连接的状态是否为3
//Event.KeeperState.SyncConnected的值为3
if (event.getState() == Event.KeeperState.SyncConnected) {
System.out.println("连接成功");
//计数器对象加1
countDownLatch.countDown();
}
}
});
// 等待zookeeper对象创建完成后执行
countDownLatch.await();
//获取zookeeper会话id
System.out.println(zookeeper.getSessionId());
//关闭zookeeper连接
zookeeper.close();
}
}
运行结果如下：
连接成功 72057788494839812利用Watcher接口的实现类连接：
package com.example.demo01.service;
import org.apache.zookeeper.*;
import org.apache.zookeeper.data.Stat;
import org.springframework.stereotype.Service;
import java.util.List;
import java.util.concurrent.CountDownLatch;
@Service
public class ZookeeperService implements Watcher{
//zookeeper对象
private ZooKeeper zookeeper;
//超时时间
private static final int SESSION_TIME_OUT = 5000;
//计数器对象（初始值为1）
private CountDownLatch countDownLatch = new CountDownLatch(1);
@Override
public void process(WatchedEvent event) {
if (event.getState() == Event.KeeperState.SyncConnected) {
System.out.println("连接成功！！！");
// 计时器对象+1
countDownLatch.countDown();
}
}
//连接zookeeper(地址)
public void connectZookeeper(String host) throws Exception{
zookeeper = new ZooKeeper(host, SESSION_TIME_OUT, this);
// 主线程阻塞，等待连接对象创建成功
countDownLatch.await();
}
public String createNode(String path,String data) throws Exception{
//返回创建的节点名称
return this.zookeeper.create(path,data.getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE,CreateMode.PERSISTENT);
}
public List getChildren(String path) throws KeeperException, InterruptedException{
List children = zookeeper.getChildren(path, false);
//返回该节点下的所有子节点，返回值类型为list
return children;
}
public String getData(String path) throws KeeperException, InterruptedException{
byte[] data = zookeeper.getData(path, false, new Stat());
//判断返回的”[B@2af46afd“是否为空
if (data == null) {
//为空就renturn
return "";
}
//返回经过string处理的值[B@2af46afd，结果为节点的参数（llh）
return new String(data);
}
public Stat setData(String path,String data) throws KeeperException, InterruptedException{
Stat stat = zookeeper.setData(path, data.getBytes(), -1);
// 返回获取该节点的值
return stat;
}
public void deleteNode(String path) throws InterruptedException, KeeperException{
zookeeper.delete(path, -1);
}
public String getCTime(String path) throws KeeperException, InterruptedException{
//返回的是一个stat对象，stat对象包含的-s的信息
Stat stat = zookeeper.exists(path, false);
//返回根据stat信息对象获取创建时间
return String.valueOf(stat.getCtime());
}
public Integer getChildrenNum(String path) throws KeeperException, InterruptedException{
// 返回，一个获取该节点的，所有子字节的，一个list集合，然后点size()方法就可以获取到list长度信息
return zookeeper.getChildren(path, false).size();
}
public void closeConnection() throws InterruptedException{
// 判断zookeeper连接对象是否为空，为空就关闭
if (zookeeper != null) {
zookeeper.close();
}
}
}
注：
new Stat()对象包含参数入下:
private long czxid;
private long mzxid;
private long ctime;
private long mtime;
private int version;
private int cversion;
private int aversion;
private long ephemeralOwner;
private int dataLength;
private int numChildren;
private long pzxid;
测试实现类的方法：
package com.example.demo01;
import com.example.demo01.service.ZookeeperService;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
@SpringBootTest
class Demo01ApplicationTests {
@Autowired
ZookeeperService zookeeperService;
@Test
void t1() throws Exception {
//先连接
zookeeperService.connectZookeeper("192.168.17.119:2181");
//创建
System.out.println(zookeeperService.createNode("/name", "llh"));
//获取
System.out.println(zookeeperService.getData("/name"));
//修改
System.out.println(zookeeperService.setData("/name", "liaolihui"));
//删除
zookeeperService.deleteNode("/name");
}
}
zookeeper配置集群：
注：第一步 解压3个zookeeper.tar的文件，分别取为（zk1,zk2,zk2） 第二步 分别进入（zk1,zk2,zk2） 给他们创建一个data文件夹 第三步 分别进入（zk1,zk2,zk2）的data文件夹里面创建myid文件，依次写入[1，2，3] 第四步 分别进入（zk1,zk2,zk2）的conf文件夹，分别复制zoo_sample.cfg一份，取名为zoo.cfg 第五步 分别进入（zk1,zk2,zk2）的zoo.cfg文件，修改"端口"，和添加, "server.myid的参数=zk服务器的ip:服务器之间通信端口:服务器之间投票选举主机端口" 第六步 分别启动各个服务器
遇到的问题总结：运行./zkServer.sh status
Leader（主节点、领导）
Follower（从节点、跟随者、下属）
Observer（从节点、观察者、下属）
报错？
-
解决1：检查各服务器的data文件是否一致
-
解决2：尽量同时启动，因为会检索各服务器
如果主机挂了？
-
首先重新选举leader,再正常对外服务
-
大概原理：会比较zxid事务id，谁最大有几率成为主机，如果zxid相同时，则比较他们的myid的值
