Invoker的invokeCommand()用来给Client调用，内部执行
Invoker:abst
+ command:type = Command
+ setCommand(Command):void+ invokeCommand():void
Client创建的时候需要指定Invoker，创建命令里面需要调用invoker.setCommand()方法保存该Command
创建Command对象的时候需要传入Receiver对象，对外提供excute、undo接口，实际上是调用Receiver
Command:abst
+ receiver:type = receiver
+ excute():void+ undo():void
Client：abst
+ invoker:type = Invoker
+ createCommand(params):void
Receiver
+ lightOn():void+ lightOff():void
![处理[命令+数据]](https://www.processon.com/chart_image/template/thumb/5505aa3be4b03108ad55e45b.png?tid=55059bd9e4b07f960cbd4b9d)