We can see the above code; Player-to-player coupling code has been removed, However, all logical operations are put into the intermediary object for processing. Any operation of a certain player does not need to traverse to notify other players, but only needs to send a message to the intermediary. The intermediary processes the message after receiving it, and after processing the message, the processing result will be fed back to other player objects. The intermediary mode is used to remove the coupling code between objects. Make the program more flexible.
