zookeeper 服务端上下线,客户端感知

时间:2021-02-11 16:51:47
package pfs.y2017.m11.zookeeper.demo03;

import java.util.ArrayList;
import java.util.List;

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

public class DistributedClient {

private static final String connectString = "192.168.1.192:2181,192.168.1.55:2181,192.168.1.28:2181";
private static final int sessionTimeout = 2000;
private static final String parentNode = "/servers";
// 注意:加volatile的意义何在?
private volatile List<String> serverList;
private ZooKeeper zk = null;

/**
* 创建到zk的客户端连接
*
*
@throws Exception
*/
public void getConnect() throws Exception {

zk
= new ZooKeeper(connectString, sessionTimeout, new Watcher() {
@Override
public void process(WatchedEvent event) {
// 收到事件通知后的回调函数(应该是我们自己的事件处理逻辑)
try {
//重新更新服务器列表,并且注册了监听
getServerList();

}
catch (Exception e) {
}
}
});

}

/**
* 获取服务器信息列表
*
*
@throws Exception
*/
public void getServerList() throws Exception {

// 获取服务器子节点信息,并且对父节点进行监听
List<String> children = zk.getChildren(parentNode, true);

// 先创建一个局部的list来存服务器信息
List<String> servers = new ArrayList<String>();
for (String child : children) {
// child只是子节点的节点名
byte[] data = zk.getData(parentNode + "/" + child, false, null);
servers.add(
new String(data));
}
// 把servers赋值给成员变量serverList,已提供给各业务线程使用
serverList = servers;

//打印服务器列表
System.out.println(serverList);

}

/**
* 业务功能
*
*
@throws InterruptedException
*/
public void handleBussiness() throws InterruptedException {
System.out.println(
"client start working.....");
Thread.sleep(Long.MAX_VALUE);
}




public static void main(String[] args) throws Exception {

// 获取zk连接
DistributedClient client = new DistributedClient();
client.getConnect();
// 获取servers的子节点信息(并监听),从中获取服务器信息列表
client.getServerList();

// 业务线程启动
client.handleBussiness();

}

}

 

 

package pfs.y2017.m11.zookeeper.demo03;

import java.util.List;

import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.ZooKeeper;

public class DistributedServer {
private static final String connectString = "192.168.1.192:2181,192.168.1.55:2181,192.168.1.28:2181";
private static final int sessionTimeout = 2000;
private static final String parentNode = "/servers";

private ZooKeeper zk = null;

/**
* 创建到zk的客户端连接
*
*
@throws Exception
*/
public void getConnect() throws Exception {

zk
= new ZooKeeper(connectString, sessionTimeout, new Watcher() {
@Override
public void process(WatchedEvent event) {
// 收到事件通知后的回调函数(应该是我们自己的事件处理逻辑)
System.out.println(event.getType() + "---" + event.getPath());
try {
zk.getChildren(
"/", true);
}
catch (Exception e) {
}
}
});

}

/**
* 向zk集群注册服务器信息
*
*
@param hostname
*
@throws Exception
*/
public void registerServer(String hostname) throws Exception {

String create
= zk.create(parentNode + "/server", hostname.getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);
System.out.println(hostname
+ "is online.." + create);

}

/**
* 业务功能
*
*
@throws InterruptedException
*/
public void handleBussiness(String hostname) throws InterruptedException {
System.out.println(hostname
+ "start working.....");
Thread.sleep(Long.MAX_VALUE);
}

public static void main(String[] args) throws Exception {

// 获取zk连接
DistributedServer server = new DistributedServer();
server.getConnect();

// 利用zk连接注册服务器信息
server.registerServer(args[0]);

// 启动业务功能
server.handleBussiness(args[0]);

}

}