Delphi Command模式

这个例子还是比较好理解的， 所以只给出代码.
unit pattern;
interface
uses Dialogs;
type
TAudioPlayer = class;
TCommand = class
public
procedure execute; virtual; abstract;
end;
TPlayCommand = class(TCommand)
private
AudioPlayer: TAudioPlayer;
public
procedure execute; override;
procedure Playcommand(AP: TAudioPlayer);
end;
TStopCommand = class(TCommand)
private
AudioPlayer: TAudioPlayer;
public
procedure execute; override;
procedure StopComman(AP: TAudioPlayer);
end;
TRewindCommand = class(TCommand)
private
AudioPlayer: TAudioPlayer;
public
procedure execute; override;
procedure RewindCommand(AP: TAudioPlayer);
end;
TKeyPad = class
private
PlayCommand: TCommand;
StopCommand: TCommand;
RewindCommand: TCommand;
public
constructor Create(PlayC, StopC, RewindC: TCommand); virtual;
procedure play();
procedure stop();
procedure rewind();
end;
TAudioPlayer = class
public
procedure play();
procedure stop();
procedure rewind();
end;
TClient = class
private
KeyPad: TKeyPad;
AudioPlayer: TAudioPlayer;
public
constructor Create();
procedure test();
end;
implementation
{ TKeyPad }
constructor TKeyPad.Create(PlayC, StopC, RewindC: TCommand);
begin
PlayCommand := PlayC;
StopCommand := StopC;
RewindCommand := RewindC;
end;
procedure TKeyPad.play;
begin
PlayCommand.execute;
end;
procedure TKeyPad.rewind;
begin
RewindCommand.execute;
end;
procedure TKeyPad.stop;
begin
StopCommand.execute;
end;
{ TAudioPlayer }
procedure TAudioPlayer.play;
begin
ShowMessage(′play′);
end;
procedure TAudioPlayer.rewind;
begin
ShowMessage(′rewind′);
end;
procedure TAudioPlayer.stop;
begin
ShowMessage(′stop′);
end;
{ TPlayCommand }
procedure TPlayCommand.execute;
begin
inherited;
AudioPlayer.play();
end;
procedure TPlayCommand.Playcommand(AP: TAudioPlayer);
begin
self.AudioPlayer := AP;
end;
{ TRewindCommand }
procedure TRewindCommand.execute;
begin
inherited;
AudioPlayer.Rewind;
end;
procedure TRewindCommand.RewindCommand(AP: TAudioPlayer);
begin
AudioPlayer := ap;
end;
{ TStopCommand }
procedure TStopCommand.execute;
begin
inherited;
AudioPlayer.Stop;
end;
procedure TStopCommand.StopComman(AP: TAudioPlayer);
begin
AudioPlayer := ap;
end;
{ TClient }
constructor TClient.Create;
begin
AudioPlayer := TAudioPlayer.Create();
end;
procedure TClient.test;
var
PlayCommand: TCommand;
StopCommand: TCommand;
RewindCommand: TCommand;
begin
PlayCommand := TPlayCommand.Create;
StopCommand := TStopCommand.Create;
RewindCommand := TRewindCommand.Create;
KeyPad := TKeyPad.Create(PlayCommand, StopCommand, RewindCommand);
KeyPad.stop;
KeyPad.play;
KeyPad.rewind;
KeyPad.Stop;
end;
end.