参考:
http://blog.wenxuecity.com/blogview.php?date=201112&postID=103
http://blog.wenxuecity.com/blogview.php?date=201012&postID=27304
http://blog.wenxuecity.com/blogview.php?date=201108&postID=4931
http://blog.wenxuecity.com/blogview.php?date=201012&postID=27279