一、监听某一节点内容
/**
* @author: PrincessHug
* @date: 2019/2/25, 14:28
* @Blog: https://www.cnblogs.com/HelloBigTable/
* 监听一个节点内容的变化
*/
public class WatchZoneDemo {
ZooKeeper zkCli = null; public static void main(String[] args) throws IOException, InterruptedException {
WatchZoneDemo wz = new WatchZoneDemo();
wz.getConnection();
Thread.sleep(Long.MAX_VALUE);
} private void getConnection() throws IOException {
zkCli = new ZooKeeper("192.168.126.128:2181,192.168.126.129:2181,192.168.126.130:2181", 3000, new Watcher() {
public void process(WatchedEvent watchedEvent) {
try {
byte[] data = zkCli.getData("/Wyh", true, null);
System.out.println("监听类型为：" + watchedEvent.getType());
System.out.println("监听路径为：" + watchedEvent.getPath());
System.out.println("数据被修改为：" + new String(data));
System.out.println("=======================================");
} catch (KeeperException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
});
}
}
二、监听某节点目录的变化
/**
* @author: PrincessHug
* @date: 2019/2/25, 14:57
* @Blog: https://www.cnblogs.com/HelloBigTable/
* 监听一个节点的子节点的变化
*/
public class WatchChildrenDemo {
ZooKeeper zkCli = null; public static void main(String[] args) throws IOException, InterruptedException {
WatchChildrenDemo wc = new WatchChildrenDemo();
wc.getConnction();
Thread.sleep(Long.MAX_VALUE);
} private void getConnction() throws IOException {
zkCli = new ZooKeeper("192.168.126.128:2181,192.168.126.129:2181,192.168.126.130:2181", 3000, new Watcher() {
public void process(WatchedEvent watchedEvent) {
ArrayList<String> nodes = new ArrayList<String>();
try {
List<String> children = zkCli.getChildren("/", true);
for (String c:children){
nodes.add(c);
}
System.out.println(nodes);
} catch (KeeperException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
});
}
}
三、Zookeeper当太上下线的感知系统
1.需求：某分布式系统中，主节点有多台，可以进行动态上下限，当有任何一台机器发生了动态的上下线， 任何一台客户端都能感知得到
2.思路：
(1)创建客户端与服务端
(2)启动client端 并监听
(3)启动server端 并注册
(4)当server端发生上下线
(5)client端都能感知的到
3.代码
public class ZKServer {
ZooKeeper zk = null;
private String parentNode = "/Servers";
public static void main(String[] args) throws IOException, KeeperException, InterruptedException {
String childNode = "hd1-1";
ZKServer zkServer = new ZKServer();
//获取连接
zkServer.getConnection();
//注册信息
zkServer.regist(childNode);
//业务逻辑，提示上线
zkServer.build(childNode);
}
private void build(String hostname) throws InterruptedException {
System.out.println(hostname + "上线了！！");
Thread.sleep(Long.MAX_VALUE);
}
private void regist(String hostname) throws KeeperException, InterruptedException {
String path = zk.create(parentNode + "/server", hostname.getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);
System.out.println(path);
}
private void getConnection() throws IOException {
zk = new ZooKeeper("192.168.126.128:2181,192.168.126.129:2181,192.168.126.130:2181", 3000, new Watcher() {
public void process(WatchedEvent watchedEvent) {
}
});
}
}
public class ZKClient {
ZooKeeper zk = null;
public static void main(String[] args) throws IOException, KeeperException, InterruptedException {
ZKClient zkClient = new ZKClient();
zkClient.getConnection();
zkClient.watching();
}
private void watching() throws InterruptedException {
Thread.sleep(Long.MAX_VALUE);
}
private void getConnection() throws IOException {
zk = new ZooKeeper("192.168.126.128:2181,192.168.126.129:2181,192.168.126.130:2181", 3000, new Watcher() {
public void process(WatchedEvent watchedEvent) {
try {
List<String> children = zk.getChildren("/Servers", true);
ArrayList<String> node = new ArrayList<String>();
for (String c:children){
byte[] data = zk.getData("/Servers/" + c, true, null);
node.add(new String(data));
}
System.out.println(node);
} catch (KeeperException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
});
}
}