http://wmq534.iteye.com/blog/1096491
http://www.cnblogs.com/preftest/archive/2011/09/30/2196444.html
http://blog.csdn.net/big1980/article/details/6152691
http://blog.csdn.net/lff0305/article/details/50236263
http://lipeng200819861126-126-com.iteye.com/blog/2042775
http://ahangliu.blog.51cto.com/9917468/1635947
http://blog.csdn.net/xch_w/article/details/7933424