http://wenku.baidu.com/link?url=dTJpXcL0TXslGAYYC6SSOrPGvjyEb974ZGx9-0dymU32YDjxuP8DwlI1sFpPCGqu_ywWjnVuhkKYROGG8aDYiOMXJApS4gG5I4sJ9Av6v6C
http://blog.csdn.net/duanml61/article/details/8585440
http://oma1989.iteye.com/blog/1732982