Head First 设计模式之命令模式

1、Head First 设计模式之命令模式前言： 本章会将封装带入到一个全新的境界，把方法调用封装起来。通过封装方法调用，把运算块包装成形。调用此运算的对象不需要知道事情是如何进行的，只要知道如何使用包装形成的方法来完成它就ok了。1 现实场景应用现在有一个遥控器，该遥控器有7个插槽需要编程，可以在每个插槽上放上不同的装置，然后用按钮控制它，这七个插槽具备各自的“开”“关”按钮，还有一个整体用的撤销按钮，会撤销最后一个按钮的动作。1.1 创建第一个命令对象1.1.1 定义命令接口csharp view plain copy 在CODE上查看代码片派生到我的代码片public interfaceC

2、ommand void Execute(); 1.1.2 实现一个打开灯的命令csharp view plain copy 在CODE上查看代码片派生到我的代码片publicclass Light /电灯类 public void On() System.Console.WriteLine("Light is On !"); public void Off() System.Console.WriteLine("Light is Off !"); public class LightOnCommand : Command/实现开灯命令 private L

3、ight light; public LightOnCommand(Light light) this.light = light; public void Execute() light.On(); 1.1.3 使用命令对象csharp view plain copy 在CODE上查看代码片派生到我的代码片public class LightControl privateCommand soft; publicvoid SetCommand(Command cmd) soft= cmd;/设置命令对象 publicvoid ButtonWasPressed() soft.Execute();

4、/调用命令对象的方法 1.1.4 简单测试csharp view plain copy 在CODE上查看代码片派生到我的代码片LightControl lightControl = new LightControl();/模拟命令的调用者 Lightlight = new Light();/创建一个电灯对象，作为命令的接收者 LightOnCommand lightOnCommand = new LightOnCommand(light);/创建一个命令，并将接受者传递给它 lightControl.SetCommand(lightOnCommand);/将命令传给调用者 lightContr

5、ol.ButtonWasPressed();/模拟触发按钮 1.2 实现遥控器csharp view plain copy 在CODE上查看代码片派生到我的代码片public class RemoteControl Command onCommands;/定义打开的命令数组 Command offCommands; /定义关闭的命令数组 public RemoteControl() onCommands = new Command7; offCommands = new Command7; Command noCommand = newNoCommand(); for (int i = 0;

6、i < 7; i+) onCommandsi = noCommand;/初始化命令数组（默认设置为无命令） offCommandsi = noCommand; /将命令设置到对应的控制器 public void SetCommand(int index,Command onCommand, Command offCommand) onCommandsindex = onCommand; offCommandsindex = offCommand; /触发打开控制器 public void OnButtonWasPressed(int index) onCommandsindex.Exec

7、ute(); /触发关闭控制器 public void OffButtonWasPressed(intindex) offCommandsindex.Execute(); public override string ToString() StringBuilder str = newStringBuilder(); str.Append("n-RemoteControl -n"); for (int i = 0; i <onCommands.Length; i+) str.Append("solt" +i + "" + onC

8、ommandsi.GetType().FullName + " " +offCommandsi.GetType().FullName + "n"); return str.ToString(); 1.3 实现其他控制器csharp view plain copy 在CODE上查看代码片派生到我的代码片 /关闭电灯命令 public classLightOffCommand : Command privateLight light; publicLightOffCommand(Light light) this.light = light; publicv

9、oid Execute() light.Off(); publicvoid Undo() light.On(); /打开电扇命令 public class CeilingFanOnCommand : Command CeilingFan ceilingFan; intpreSpeed; publicCeilingFanOnCommand(CeilingFan ceilingFan) this.ceilingFan = ceilingFan; publicvoid Execute() ceilingFan.On(); publicvoid Undo() ceilingFan.Off(); /关闭

10、电扇命令 public classCeilingFanOffCommand : Command CeilingFan ceilingFan; publicCeilingFanOffCommand(CeilingFan ceilingFan) this.ceilingFan = ceilingFan; publicvoid Execute() ceilingFan.Off(); publicvoid Undo() ceilingFan.On(); /打开车库门命令 public classGarageDoorOnCommand : Command GarageDoor garageDoor; p

11、ublicGarageDoorOnCommand(GarageDoor garageDoor) this.garageDoor= garageDoor; publicvoid Execute() garageDoor.On(); publicvoid Undo() garageDoor.Off(); /关闭车库门命令 public classGarageDoorOffCommand : Command GarageDoor garageDoor; publicGarageDoorOffCommand(GarageDoor garageDoor) this.garageDoor = garage

12、Door; publicvoid Execute() garageDoor.Off(); publicvoid Undo() garageDoor.On(); /打开CD命令 public classStereCDOnCommand : Command StereCDstereCD; publicStereCDOnCommand(StereCD stereCD) this.stereCD = stereCD; publicvoid Execute() stereCD.On(); publicvoid Undo() stereCD.Off(); /关闭CD命令 public classStere

13、CDOffCommand : Command StereCDstereCD; publicStereCDOffCommand(StereCD stereCD) this.stereCD = stereCD; publicvoid Execute() stereCD.Off(); publicvoid Undo() stereCD.On(); 1.4简单测试csharp view plain copy 在CODE上查看代码片派生到我的代码片RemoteControlremoteControl = new RemoteControl (); CeilingFan ceilingFan = newC

14、eilingFan("Living Room");/创建电扇对象 GarageDoor garageDoor = newGarageDoor();/创建车库门对象 StereCD stereCD = new StereCD();/创建CD对象 Light light = new Light();/创建电灯对象 LightOnCommand lightOnCommand = newLightOnCommand(light);/创建开灯命令 LightOffCommand lightOffCommand =new LightOffCommand(light); /创建关灯命令

15、CeilingFanOnCommandceilingFanOn = new CeilingFanOnCommand(ceilingFan); /创建开电扇命令 CeilingFanOffCommand ceilingFanOff= new CeilingFanOffCommand(ceilingFan);/创建关电扇命令 GarageDoorOnCommand garageDoorOn =new GarageDoorOnCommand(garageDoor);/创建打开电扇命令 GarageDoorOffCommand garageDoorOff= new GarageDoorOffComma

16、nd(garageDoor);/创建关闭电扇命令 StereCDOnCommand stereCDOn = newStereCDOnCommand(stereCD);/创建打开CD命令 StereCDOffCommand stereCDOff = newStereCDOffCommand(stereCD);/创建关闭CD命令 remoteControl.SetCommand(0,lightOnCommand, lightOffCommand);/将电灯命令设置到对应的控制器上 Control.SetCommand(1,ceilingFanOn, ceilingFanOff); /将电灯命令设置

17、到对应的控制器上 remoteControl.SetCommand(2,garageDoorOn, garageDoorOff); /将车库门命令设置到对应的控制器上 remoteControl.SetCommand(3,stereCDOn, stereCDOff); /将CD命令设置到对应的控制器上 remoteControl.OnButtonWasPressed(0); remoteControl.OffButtonWasPressed(0); remoteControl.OnButtonWasPressed(1); remoteControl.OffButtonWasPressed(1)

18、; remoteControl.OnButtonWasPressed(2); remoteControl.OffButtonWasPressed(2); remoteControl.OnButtonWasPressed(3); remoteControl.OffButtonWasPressed(3); 1.5 实现撤销命令1.5.1 修改命令接口，新增Undo（）方法csharp view plain copy 在CODE上查看代码片派生到我的代码片public interfaceCommand void Execute(); void Undo();/新增撤销方法 1.5.2 修改命令，实现

19、Undo方法csharp view plain copy 在CODE上查看代码片派生到我的代码片public class LightOnCommand : Command private Light light; public LightOnCommand(Light light) this.light = light; public void Execute() light.On(); public void Undo()/实现Undo方法 light.Off(); 其他类都依次修改1.5.3 修改RemoteControl类，新增Command对象记录上一步操作csharp view pl

20、ain copy 在CODE上查看代码片派生到我的代码片public class RemoteControlWithUndo Command onCommands; Command offCommands; CommandundoCommand;/创建Command对象用来记录上一步执行的命令 publicRemoteControlWithUndo() onCommands = new Command7; offCommands = new Command7; Command noCommand = new NoCommand(); for(int i = 0; i < 7; i+) o

21、nCommandsi = noCommand; offCommandsi = noCommand; undoCommand = noCommand; . publicvoid OnButtonWasPressed(int index) onCommandsindex.Execute(); undoCommand = onCommandsindex;/记录打开命令 publicvoid OffButtonWasPressed(int index) offCommandsindex.Execute(); undoCommand = offCommandsindex;/记录关闭命令 publicvo

22、id UndoButtonWasPressed()/执行撤销 undoCommand.Undo(); 1.6 宏命令让遥控器具有Party模式，即一个按键能够同步调用多个命令，这就是所谓的宏命令。 csharp view plain copy 在CODE上查看代码片派生到我的代码片public class MacroCommand : Command Command commands;/定义命令数组，用来接收传入的命令 public MacroCommand(Command commands) mands = commands; public void Execute()/批量处理多个命令（即初始化的时候传入的命令数组） for (int i = 0; i <commands.Length; i+) commandsi.Execute(); public void Undo() for (int i = 0; i <