C # Object-oriented design--command mode (15)

First, preface

The command pattern encapsulates a request as an object, allowing you to parameterize the customer with different requests, queue up requests or log requests, and support revocable operations.

Second, the structure diagram

Third, instance code

namespaceCommand mode {classProgram {Static voidMain (string[] args) {            //pre-opening preparationBarbecuer boy =NewBarbecuer (); Command BakeMuttonCommand1=NewBakemuttoncommand (boy); Command BakeMuttonCommand2=NewBakemuttoncommand (boy); Command BakeChickenWingCommand1=NewBakechickenwingcommand (boy); Waiter Girl=NewWaiter (); //Open Customer OrderGirl.            Setorder (BAKEMUTTONCOMMAND1); Girl.            Setorder (BAKEMUTTONCOMMAND2); Girl.            Setorder (BAKECHICKENWINGCOMMAND1); //close the order and inform the kitchenGirl.            Notify ();        Console.read (); }    }    //Waiter     Public classWaiter {Privateilist<command> orders =NewList<command>(); //Set up orders         Public voidsetorder (Command command) {if(command.) ToString () = ="Command mode. Bakechickenwingcommand") {Console.WriteLine ("Waiter: Chicken Wing No, please order other barbecue. "); }            Else{orders.                ADD (command); Console.WriteLine ("Add Order:"+ command. ToString () +"Time:"+DateTime.Now.ToString ()); }        }        //Cancel Order         Public voidcancelorder (Command command) {orders.            Remove (command); Console.WriteLine ("Cancel Order:"+ command. ToString () +"Time:"+DateTime.Now.ToString ()); }        //all notifications are executed         Public voidNotify () {foreach(Command cmdinchorders) {cmd.            Excutecommand (); }        }    }    //Abstract Commands     Public Abstract classCommand {protectedBarbecuer Receiver;  PublicCommand (Barbecuer receiver) { This. Receiver =receiver; }        //Execute Command        Abstract  Public voidExcutecommand (); }    //Lamb Kebab Command    classBakemuttoncommand:command { PublicBakemuttoncommand (Barbecuer receiver):Base(receiver) {} Public Override voidExcutecommand () {receiver.        Bakemutton (); }    }    //Grilled chicken Wings Command    classBakechickenwingcommand:command { PublicBakechickenwingcommand (Barbecuer receiver):Base(receiver) {} Public Override voidExcutecommand () {receiver.        Bakechickenwing (); }    }    //Grill Skewers     Public classBarbecuer { Public voidBakemutton () {Console.WriteLine ("Roast kebabs!"); }         Public voidbakechickenwing () {Console.WriteLine ("Grilled chicken wings!"); }    }}

Iv. Summary

Command mode Advantages:
First, it is relatively easy to design a command queue.
Second, the command can be entered into the log, if needed.
Third, allow the party receiving the request to decide whether to veto the request.
Finally, it is easier to implement the revocation and redo of the request.
Since the new specific request command class and other command classes do not affect each other, it is easy to add a specific command class.
The biggest advantage is that the command mode separates a request operand from the object that knows how to perform the operation.

V. Other examples

namespaceCommand mode {classProgram {Static voidMain (string[] args) {Receiver R=NewReceiver (); Command C=NewConcretecommand (R); Invoker I=NewInvoker (); //Set and execute commandI.setcommand (c);            I.executecommand ();        Console.read (); }    }    Abstract classCommand {protectedreceiver receiver;  PublicCommand (receiver receiver) { This. Receiver =receiver; }        Abstract  Public voidExecute (); }    classConcretecommand:command { PublicConcretecommand (receiver receiver):Base(receiver) {} Public Override voidExecute () {receiver.        Action (); }    }    classReceiver { Public voidAction () {Console.WriteLine ("Execute the request! "); }    }    classInvoker {PrivateCommand command;  Public voidsetcommand (Command command) { This. Command =command; }         Public voidExecuteCommand () {command.        Execute (); }    }}

C # Object-oriented design--command mode (15)