http://www.cnblogs.com/JMDWQ/archive/2012/05/20/2510698.html
http://baike.baidu.com/view/614354.htm?fr=aladdin
http://wenku.baidu.com/link?url=UWWBEOE_qC_qY4OTMpYMPq1tsM4DUXWCFq4VAmlAm_KTq99CDk2qhY-ZjlUzh09Wwf_UmKqpMrjd7UiK01Ee1yZ1chGhzdVvd1c6tiKzndC