参考:
http://blog.youkuaiyun.com/hanzengyi/article/details/8473667
http://blog.163.com/yun_2527/blog/static/352718612010111510539604/
http://enchen.blog.51cto.com/716040/183227
http://blog.youkuaiyun.com/joans123/article/details/6586428
http://blog.youkuaiyun.com/xiaokeweng/article/details/8783226
http://blog.youkuaiyun.com/xiaokeweng/article/details/8788113