./zkServer.sh start
./zkServer.sh status
./zkServer.sh stop
./zkServer.sh restart
@Test
public void testConnect() {//重试策略ExponentialBackoffRetry retry = new ExponentialBackoffRetry(3000, 10);//第一种方式CuratorFramework client = CuratorFrameworkFactory.newClient("192.168.130.120:2181", 60 * 1000, 15 * 1000, retry);//第二种方式CuratorFramework client1 = CuratorFrameworkFactory.builder().connectString("192.168.130.120:2181").sessionTimeoutMs(60 * 1000).connectionTimeoutMs(15 * 1000).retryPolicy(retry).namespace("hrbu").build();//开启连接client.start();
}
参数解读
会话超时时间和连接超时时间有默认值。
第二种链式编程的方式可以指定一个工作空间,在此客户端下的所有操作都会将此工作空间作为根目录。
注意
如果使用的是云服务器需要将指定端口打开
firewall-cmd --zone=public --add-port=2181/tcp --permanent
开放端口
firewall-cmd --zone=public --list-ports
查看已经开放的端口
systemctl restart firewalld
重启防火墙生效
最后别忘了在服务器的安全组里面添加端口,将2181端口打开
@Test
public void testCreate1() throws Exception {//基本创建CreateBuilder createBuilder = client.create();//创建时不指定数据,会将当前客户端ip存到里面createBuilder.forPath("/app1");//指定数据createBuilder.forPath("/app2", "hello".getBytes());
}@Test
public void testCreate2() throws Exception {CreateBuilder createBuilder = client.create();//设置节点类型,默认的类型是持久化//CreateMode是枚举类型createBuilder.withMode(CreateMode.EPHEMERAL).forPath("/app3");
}@Test
public void testCreate3() throws Exception {CreateBuilder createBuilder = client.create();//创建多级节点,如果父节点不存在,则创建父节点。createBuilder.creatingParentContainersIfNeeded().forPath("/app4/app4_1");
}
@Test
public void testGet() throws Exception {//查询数据byte[] bytes = client.getData().forPath("/app1");System.out.println(new String(bytes));//查询子节点List strings = client.getChildren().forPath("/app4");strings.forEach(System.out::println);//查询节点状态信息Stat stat = new Stat();client.getData().storingStatIn(stat).forPath("/app1");System.out.println(stat);
}
@Test
public void testSet() throws Exception {//修改数据client.setData().forPath("/app1","hrbu".getBytes());//根据版本修改int version = 0;Stat stat = new Stat();client.getData().storingStatIn(stat).forPath("/app1");version = stat.getVersion();client.setData().withVersion(version).forPath("/app1", "HRBU".getBytes());
}
@Test
public void testDelete() throws Exception {//删除单个节点client.delete().forPath("/app4/app4_1");//删除带有子节点的节点client.delete().deletingChildrenIfNeeded().forPath("/app4");//强制删除client.delete().guaranteed().forPath("/app4");//回调client.delete().guaranteed().inBackground(new BackgroundCallback() {@Overridepublic void processResult(CuratorFramework client, CuratorEvent event) throws Exception {System.out.println("执行删除操作");}}).forPath("/app4");}
Zookeeper允许用户在指定节点上注册一些Watcher,并且在一些特定事件触发的时候,ZooKeeper服务端会将事件通知到感兴趣的客户端上去,该机制是ZooKeeper实现分布式协调服务的重要特性。
ZooKeeper中引入了Watcher机制来实现了发布/订阅功能,能够让多个订阅者同时监听某一个对象,当一个对象自身状态变化时,会通知所有订阅者。
ZooKeeper原生支持通过注册Watcher来进行事件监听,但是使用并不是特别方便,需要开发人员自己反复注册Watcher,比较繁琐。
Curator引入了Cache来时限对Zookeeper服务端事件的监听。
ZooKeeper提供了三种Watcher:
NodeCache
@Test
public void testNodeCache() throws Exception {//NodeCache:指定一个节点注册监听器//创建NodeCache对象final NodeCache nodeCache = new NodeCache(client, "/app1");//注册监听nodeCache.getListenable().addListener(new NodeCacheListener() {@Overridepublic void nodeChanged() throws Exception {System.out.println("app1节点发生变化");//获取修改节点后的数据byte[] data = nodeCache.getCurrentData().getData();System.out.println("变化后的节点:"+new String(data));}});//开启监听,如果为true,则开启则开启监听,加载缓冲数据nodeCache.start(true);
}
PathChildrenCache
@Test
public void testPathChildrenCache() throws Exception {//PathChildrenCache:监听某个节点的所有子节点//创建监听对象PathChildrenCache pathChildrenCache = new PathChildrenCache(client, "/hrbu", true);//绑定监听器pathChildrenCache.getListenable().addListener(new PathChildrenCacheListener() {@Overridepublic void childEvent(CuratorFramework curatorFramework, PathChildrenCacheEvent pathChildrenCacheEvent) throws Exception {System.out.println("子节点发生变化");System.out.println(pathChildrenCacheEvent);//监听子节点的数据变更,并且得到变更后的数据//获取类型PathChildrenCacheEvent.Type type = pathChildrenCacheEvent.getType();//判断类型if (type.equals(PathChildrenCacheEvent.Type.CHILD_UPDATED)) {//获取数据byte[] data = pathChildrenCacheEvent.getData().getData();System.out.println(new String(data));}}});//开启pathChildrenCache.start();
}
TreeCache
@Test
public void testTreeCache() throws Exception {//创建监听器TreeCache treeCache = new TreeCache(client, "/");//注册监听treeCache.getListenable().addListener(new TreeCacheListener() {@Overridepublic void childEvent(CuratorFramework curatorFramework, TreeCacheEvent treeCacheEvent) throws Exception {System.out.println("节点发生变化");System.out.println(treeCacheEvent);}});//开启treeCache.start();}
在Curator中有五种锁方案:
package com.hrbu.curator;import org.apache.curator.RetryPolicy;
import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.recipes.locks.InterProcessMutex;
import org.apache.curator.retry.ExponentialBackoffRetry;import java.util.concurrent.TimeUnit;public class Ticket12306 implements Runnable{private int tickets = 10;//数据库的票数private InterProcessMutex lock ;public Ticket12306(){//重试策略RetryPolicy retryPolicy = new ExponentialBackoffRetry(3000, 10);CuratorFramework client = CuratorFrameworkFactory.builder().connectString("8.130.32.75:2181").sessionTimeoutMs(60 * 1000).connectionTimeoutMs(15 * 1000).retryPolicy(retryPolicy).build();//开启连接client.start();lock = new InterProcessMutex(client,"/lock");}@Overridepublic void run() {while(true){//获取锁try {lock.acquire(3, TimeUnit.SECONDS);if(tickets > 0){System.out.println(Thread.currentThread()+":"+tickets);Thread.sleep(100);tickets--;}} catch (Exception e) {e.printStackTrace();}finally {//释放锁try {lock.release();} catch (Exception e) {e.printStackTrace();}}}}
}
package com.hrbu.curator;public class LockTest {public static void main(String[] args) {Ticket12306 ticket12306 = new Ticket12306();//创建客户端Thread t1 = new Thread(ticket12306,"携程");Thread t2 = new Thread(ticket12306,"飞猪");t1.start();t2.start();}
}