http://www.cnblogs.com/grantvip/archive/2008/10/17/1313239.html
http://blog.chinaunix.net/u/8036/showart_233356.html
http://blog.csdn.net/fableking/archive/2008/05/22/2470864.aspx
http://blog.csdn.net/junkaih2008/archive/2008/07/15/2653142.aspx:这篇写得还不错