三段式状态机写法 转载: 1:https://www.cnblogs.com/jiang-ic/p/8119079.html 2:https://www.cnblogs.com/littlexiaocai/archive/2012/05/30/2526716.html 3:https://www.cnblogs.com/qidaiymm/p/4908724.html 4:https://www.cnblogs.com/sgh69/p/5743451.html