下面这篇博客,很详细,基于源码:
https://my.oschina.net/u/4933191/blog/4896611
下面这篇博客基于案例,生动:
https://www.cnblogs.com/code-duck/p/13433809.html
常用方法:
https://www.cnblogs.com/bingsying/p/12507419.html