http://blog.youkuaiyun.com/liuhe688/article/details/6852523 http://www.it165.net/pro/html/201308/6827.html http://www.cnblogs.com/jdsjlzx/archive/2011/07/19/2110936.html http://www.cnblogs.com/allin/archive/2010/05/11/1732200.html