简介

原理规则

参考案例

扩展

参考链接:
http://wenku.baidu.com/link?url=FLbB1d-cPj5uuxsaORgTaLYDUcEwziU4VFE3dHzIxv_2UNwvBiBAo4_n5D2n9zbmgM3kJMJHKOptYbd6bJd21sHtDIOLysViDIHcHN5UpgK
http://wenku.baidu.com/link?url=_jgyTFPUC5EdnDykoVR-hbtutdNnZjgOhlbHaJ0Ipcy04SZiLHCaUY2zTyiZjn4WpNPxQZUDtBXJD5Z1K56EUffQ7nk3qM5lxH0ux9Qz7OS
http://blog.csdn.net/husion01/article/details/17440333