public static void pullMsg() {
		//这里为了方便测试,也是类似心跳推送
		while (true) {
			try {
				Thread.sleep(3000);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
			//遍历所有维持链接的client,发送消息。忽略掉宕机的client
			for (String client : ServerMain.channelMap.keySet()) {
				Channel channel = ServerMain.channelMap.get(client);
				serverSendMsg(channel,client);
			}
			
		} 
	}