C# 设计模式系列教程-命令模式

 /// <summary>
 /// 接收者类，知道如何实施与执行一个请求相关的操作，任何类都可能作为一个接收者。
 /// </summary>
 public class Receiver
 {
  /// <summary>
  /// 真正的命令实现
  /// </summary>
  public void Action()
  {
   Console.WriteLine("Execute request!");
  }
 }

 /// <summary>
 /// 抽象命令类，用来声明执行操作的接口
 /// </summary>
 public interface ICommand
 {
  void Execute();
 }

 /// <summary>
 /// 具体命令类，实现具体命令。
 /// </summary>
 public class ConcereteCommand : ICommand
 {
  // 具体命令类包含有一个接收者，将这个接收者对象绑定于一个动作
  private Receiver receiver;

  public ConcereteCommand(Receiver receiver)
  {
   this.receiver = receiver;
  }

  /// <summary>
  /// 说这个实现是“虚”的，因为它是通过调用接收者相应的操作来实现Execute的
  /// </summary>
  public void Execute()
  {
   receiver.Action();
  }
 }

 /// <summary>
 /// 调度类，要求该命令执行这个请求
 /// </summary>
 public class Invoker
 {
  private ICommand command;

  /// <summary>
  /// 设置命令
  /// </summary>
  /// <param name="command"></param>
  public void SetCommand(ICommand command)
  {
   this.command = command;
  }

  /// <summary>
  /// 执行命令
  /// </summary>
  public void ExecuteCommand()
  {
   command.Execute();
  }
 }

 class Program
 {
  static void Main(string[] args)
  {
   Receiver receiver = new Receiver();
   ICommand command = new ConcereteCommand(receiver);
   Invoker invoker = new Invoker();

   invoker.SetCommand(command);
   invoker.ExecuteCommand();

   Console.Read();
  }
 }

 /// <summary>
 /// 银行帐号
 /// </summary>
 public class Account
 {
  /// <summary>
  /// 帐号总金额
  /// </summary>
  private decimal totalAmount { get; set; }

  /// <summary>
  /// 存钱
  /// </summary>
  /// <param name="amount"></param>
  public void MoneyIn(decimal amount)
  {
   this.totalAmount += amount;
  }

  /// <summary>
  /// 取钱
  /// </summary>
  /// <param name="amount"></param>
  public void MoneyOut(decimal amount)
  {
   this.totalAmount -= amount;
  }

  public decimal GetTotalAmout()
  {
   return totalAmount;
  }
 }

 public abstract class Command
 {
  protected Account account;

  public Command(Account account)
  {
   this.account = account;
  }

  public abstract void Execute();
 }

 /// <summary>
 /// 存款命令
 /// </summary>
 public class MoneyInCommand : Command
 {
  private decimal amount;

  public MoneyInCommand(Account account, decimal amount)
   : base(account)
  {
   this.amount = amount;
  }

  /// <summary>
  /// 实现存钱命令
  /// </summary>
  public override void Execute()
  {
   account.MoneyIn(amount);
  }
 }

 /// <summary>
 /// 取款命令类
 /// </summary>
 public class MoneyOutCommand : Command
 {
  private decimal amount;
  public MoneyOutCommand(Account account, decimal amount)
   : base(account)
  {
   this.amount = amount;
  }

  /// <summary>
  /// 实现取钱命令
  /// </summary>
  public override void Execute()
  {
   account.MoneyOut(amount);
  }
 }

 public class Invoker
 {
  private Command command;

  public void SetCommand(Command command)
  {
   this.command = command;
  }

  public void ExecuteCommand()
  {
   command.Execute();
  }
 }

 class Program
 {
  static void Main(string[] args)
  {
   // 创建银行帐号
   Account account = new Account();
   // 创建一个存入500元的命令
   Command commandIn = new MoneyInCommand(account,500);
   // 创建一个调度者
   BankAccount.Invoker invoker = new BankAccount.Invoker();

   // 设置存钱命令
   invoker.SetCommand(commandIn);
   // 执行
   invoker.ExecuteCommand();
   Console.WriteLine("The current amount is " + account.GetTotalAmout().ToString("N2"));

   // 再次存入500
   Command commandIn2 = new MoneyInCommand(account, 500);
   invoker.SetCommand(commandIn2);
   invoker.ExecuteCommand();
   Console.WriteLine("The current amount is " + account.GetTotalAmout().ToString("N2"));

   // 取出300
   Command commandOut = new MoneyOutCommand(account, 300);
   invoker.SetCommand(commandOut);
   invoker.ExecuteCommand();
   Console.WriteLine("The current amount is " + account.GetTotalAmout().ToString("N2"));

   Console.Read();
  }
 }