http://www.cnblogs.com/newcj/archive/2011/03/14/1983782.html
http://www.cnblogs.com/shenshuyi/archive/2011/03/22/1990884.html
http://blog.csdn.net/chenzheng_java/article/details/6249357
//将此通知放到通知栏的"Ongoing"即"正在运行"组中 n.flags |= Notification.FLAG_ONGOING_EVENT; //表明在点击了通知栏中的"清除通知"后，此通知不清除 n.flags |= Notification.FLAG_NO_CLEAR;