用zookeeper实现简单的发布订阅功能

发布方Provider的代码

package com.zhuyun.release.subscribe;

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;
import org.apache.zookeeper.data.Stat;

public class Provider {
public static void main(String[] args) throws Exception {
Watcher watcher = new Watcher() {
@Override
public void process(WatchedEvent event) {
System.out.println("触发了" + event.getPath() + "的" + event.getType() + "事件！");
}
};

ZooKeeper zk = new ZooKeeper("192.168.10.203:2181", 20, watcher);

Stat stat = zk.exists("/message", watcher);
if (stat == null) { //假如节点不存在，则先创建节点
zk.create("/message", "hello".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
}

//向该节点发送消息
zk.setData("/message", "hello world".getBytes(), -1);

zk.close();
}
}


订阅方Consumer的代码：

package com.zhuyun.release.subscribe;

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 Consumer implements Watcher{
ZooKeeper zk;
String hostPort;
String znode;

public Consumer(String hostPort,String znode) throws Exception{
this.hostPort = hostPort;
this.znode = znode;

zk = new ZooKeeper(hostPort, 3000, this);
//第一次获取节点消息，同时添加watcher
System.out.println("消息内容：" + new String(zk.getData(znode, true, null)));
}

@Override
public void process(WatchedEvent event) {
if (event.getType() == EventType.NodeDataChanged) {
try {
//当节点消息变化时，触发该操作：获取变化后的消息，同时再添加watcher
System.out.println("你有新的消息:" + new String(zk.getData("/message", true, null)));

} catch (KeeperException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

public static void main(String[] args) throws Exception {
new Consumer("192.168.10.203:2181","/message");

System.in.read();
}

}


首先启动订阅方监听，再启动发布方发布消息，每次发布一条消息，订阅方都能收到该消息，结果如下：
消息内容：我是谁？
你有新的消息:hello
你有新的消息:你好
你有新的消息:hello world