一:监听服务端zookeeper节点数据改变

import java.io.IOException;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit; import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.Watcher.Event.EventType;
import org.apache.zookeeper.Watcher.Event.KeeperState;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.ZooKeeper; public class ConfigApp1 {
private static CountDownLatch connectedSemaphore = new CountDownLatch(1); public static void main(String[] args) throws IOException, KeeperException, InterruptedException {
//连接zookeeper服务器
ZooKeeper zk = new ZooKeeper("127.0.0.1:2181", 5000,
new Watcher() {
public void process(WatchedEvent event) {
if (KeeperState.SyncConnected == event.getState()) { //zk连接成功通知事件
if ( EventType.None == event.getType() && null == event.getPath() ) {
connectedSemaphore.countDown();
System.out.println("===========");
}
} }
}); connectedSemaphore.await();
//创建节点app1,不进行ACL权限控制,EPHEMERAL:临时节点
zk.create("/app1", "app1Date".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL); //注册对该节点的监听
zk.exists("/app1", new WatcherClass(zk)); //延迟2秒后 开始改变数据
TimeUnit.SECONDS.sleep(2);
for(int i = 0; i < 10; i++) {
TimeUnit.SECONDS.sleep(1);
String s = ("app" + i * 10);
zk.setData("/app1", s.getBytes(), -1);
System.out.println("数据改变了:"+s);
}
System.in.read();
} static class WatcherClass implements Watcher {
private ZooKeeper zk; public WatcherClass(ZooKeeper zk) {
this.zk = zk;
} @Override
public void process(WatchedEvent arg0) {
try {
byte[] b = zk.getData("/app1", false, null);
System.out.println("改变数据通知:" + new String(b)); //获取数据后,再次对节点进行监听
zk.exists("/app1", new WatcherClass(zk));
} catch (KeeperException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
} }
}

console结果截图:

 二:集群管理

  应用集群中,我们常常需要让每一个机器知道集群中(或依赖的其他某一个集群)哪些机器是活着的,并且在集群机器因为宕机,网络断链等原因能够不在人工介入的情况下迅速通知到每一个机器

思路:用三个类模拟成三个服务器,去连接zookeeper,这三个服务器监控zookeeper节点root,每个服务器上线都会在zookeeper的节点root下创建一个临时节点,这样,这三个服务器watcher这个zookeeper的root节点就可以动态感知服务器的上下线情况。

import java.io.IOException;
import java.util.List;
import java.util.concurrent.CountDownLatch; import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.Watcher.Event.EventType;
import org.apache.zookeeper.Watcher.Event.KeeperState;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.data.Stat;
import org.apache.zookeeper.ZooKeeper; public class Cluster1 { private static final int zkSessionTimeOut = 5000; private static CountDownLatch connectedSemaphore = new CountDownLatch(1); public static void main(String[] args) throws IOException, InterruptedException, KeeperException {
//连接zookeeper服务器
ZooKeeper zk = new ZooKeeper("127.0.0.1:2181", zkSessionTimeOut,
new Watcher() {
public void process(WatchedEvent event) {
if (KeeperState.SyncConnected == event.getState()) { //zk连接成功通知事件
if ( EventType.None == event.getType() && null == event.getPath() ) {
connectedSemaphore.countDown();
System.out.println("===========");
}
} }
}); connectedSemaphore.await(); Stat stat = zk.exists("/root", true);
if(stat == null) {
System.out.println("/root" + "路径不存在,请先创建该节点");
//创建节点root,不进行ACL权限控制,PERSISTENTAL:永久节点 只有永久节点才可以创建子节点的临时节点
zk.create("/root", "rootDate".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
}
String clusterPath = zk.create("/root/cluster1", "cluster1Date".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
System.out.println(clusterPath); ZkWatcher zkWatcher = new ZkWatcher(zk);
List<String> clusterList = zk.getChildren("/root", zkWatcher); System.out.println("****************");
for(String str : clusterList) {
System.out.println("cluster:" + str);
}
System.out.println("****************"); while(true) { }
} }
import java.io.IOException;
import java.util.List;
import java.util.concurrent.CountDownLatch; import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.Watcher.Event.EventType;
import org.apache.zookeeper.Watcher.Event.KeeperState;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.data.Stat; public class Cluster2 { private static final int zkSessionTimeOut = 5000; private static CountDownLatch connectedSemaphore = new CountDownLatch(1); public static void main(String[] args) throws IOException, InterruptedException, KeeperException {
//连接zookeeper服务器
ZooKeeper zk = new ZooKeeper("127.0.0.1:2181", zkSessionTimeOut,
new Watcher() {
public void process(WatchedEvent event) {
if (KeeperState.SyncConnected == event.getState()) { //zk连接成功通知事件
if ( EventType.None == event.getType() && null == event.getPath() ) {
connectedSemaphore.countDown();
System.out.println("===========");
}
} }
}); connectedSemaphore.await(); Stat stat = zk.exists("/root", true);
if(stat == null) {
System.out.println("/root" + "路径不存在,请先创建该节点");
zk.create("/root", "rootDate".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
}
String clusterPath = zk.create("/root/cluster2", "cluster2Date".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
System.out.println(clusterPath); ZkWatcher zkWatcher = new ZkWatcher(zk);
List<String> clusterList = zk.getChildren("/root", zkWatcher); System.out.println("****************");
for(String str : clusterList) {
System.out.println("cluster:" + str);
}
System.out.println("****************"); while(true) { }
} }
import java.io.IOException;
import java.util.List;
import java.util.concurrent.CountDownLatch; import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.Stat;
import org.apache.zookeeper.Watcher.Event.EventType;
import org.apache.zookeeper.Watcher.Event.KeeperState;
import org.apache.zookeeper.ZooDefs.Ids; public class Cluster3 { private static final int zkSessionTimeOut = 5000; private static CountDownLatch connectedSemaphore = new CountDownLatch(1); public static void main(String[] args) throws IOException, InterruptedException, KeeperException {
//连接zookeeper服务器
ZooKeeper zk = new ZooKeeper("127.0.0.1:2181", zkSessionTimeOut,
new Watcher() {
public void process(WatchedEvent event) {
if (KeeperState.SyncConnected == event.getState()) { //zk连接成功通知事件
if ( EventType.None == event.getType() && null == event.getPath() ) {
connectedSemaphore.countDown();
System.out.println("===========");
}
} }
}); connectedSemaphore.await(); Stat stat = zk.exists("/root", true);
if(stat == null) {
System.out.println("/root" + "路径不存在,请先创建该节点");
zk.create("/root", "rootDate".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
}
String clusterPath = zk.create("/root/cluster3", "cluster3Date".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
System.out.println(clusterPath); ZkWatcher zkWatcher = new ZkWatcher(zk);
List<String> clusterList = zk.getChildren("/root", zkWatcher); System.out.println("****************");
for(String str : clusterList) {
System.out.println("cluster:" + str);
}
System.out.println("****************"); while(true) { }
} }
import java.util.List;

import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.Watcher.Event.EventType;
import org.apache.zookeeper.ZooKeeper; public class ZkWatcher implements Watcher{ private ZooKeeper zk; public ZkWatcher(ZooKeeper zk) {
this.zk = zk;
} @Override
public void process(WatchedEvent event) {
if(EventType.NodeChildrenChanged.equals(event.getType())) {
List<String> clusterList = null;
try {
clusterList = zk.getChildren("/root", this);
} catch (KeeperException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
} System.out.println("****************");
System.out.println("changed");
for(String str : clusterList) {
System.out.println("cluster:" + str);
}
System.out.println("****************");
}
} }

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