http://blog.csdn.net/zdw890412/article/details/7386314  //有点乱

http://www.cnblogs.com/fanchangfa/archive/2012/08/25/2657012.html

http://www.2cto.com/kf/201403/284469.html //不错

http://blog.csdn.net/chonbj/article/details/11804153 //通俗

http://www.360doc.com/content/13/0507/19/12229927_283691996.shtml

http://www.cnblogs.com/allenzheng/archive/2013/04/28/3050065.html