http://www.cnblogs.com/aszx0413/articles/1886819.html
http://blog.csdn.net/kobbbb/article/details/8522316
http://www.helloweba.com/view-blog-275.html
http://blog.sina.com.cn/s/blog_a35991340102vpzo.html
原文：http://www.cnblogs.com/xiaopihai988/p/4712314.html