https://blog.csdn.net/u010665216/article/details/78721354?locationNum=7&fps=1html
http://www.cnblogs.com/pinard/p/7160330.htmliphone
https://www.leiphone.com/news/201706/PamWKpfRFEI42McI.html.net
https://blog.csdn.net/u014595019/article/details/51884529 这篇文章对源码进行了简单的解释,我以为讲的还不错htm