https://www.cnblogs.com/xiaoxu123/
https://juejin.im/post/6844903934377754637
https://cloud.tencent.com/developer/article/1560422
参考链接
https://www.cnblogs.com/yanlong300/p/8986041.html
https://www.jianshu.com/p/5a0669d6305e
https://www.cnblogs.com/linjiqin/p/9678022.html
https://www.runoob.com/design-pattern/command-pattern.html
https://my.oschina.net/JavaLaw/blog/1572288