http://blog.csdn.net/kk185800961/article/details/12398667
https://wenku.baidu.com/view/d16105abdd3383c4bb4cd20c.html
https://wenku.baidu.com/view/2bbab72aed630b1c59eeb55c.html
https://wenku.baidu.com/view/f61bd3f60975f46527d3e1ac.html?qq-pf-to=pcqq.c2c
https://wenku.baidu.com/view/058f5186581b6bd97f19eaf0.html?pn=51
http://www.cnblogs.com/gudujianxiao/category/350476.html