乐在其中设计模式(C#) - 命令模式(Command Pattern)

using System; 
using System.Collections.Generic; 
using System.Text; 
 
namespace Pattern.Command 
{ 
         /// <summary> 
         /// Message实体类 
         /// </summary> 
         public  class MessageModel 
        { 
                 /// <summary> 
                 /// 构造函数 
                 /// </summary> 
                 /// <param name="msg">Message内容</param> 
                 /// <param name="pt">Message发布时间</param> 
                 public MessageModel( string msg, DateTime pt) 
                { 
                         this._message = msg; 
                         this._publishTime = pt; 
                } 
 
                 private  string _message; 
                 /// <summary> 
                 /// Message内容 
                 /// </summary> 
                 public  string Message 
                { 
                        get {  return _message; } 
                        set { _message = value; } 
                } 
 
                 private DateTime _publishTime; 
                 /// <summary> 
                 /// Message发布时间 
                 /// </summary> 
                 public DateTime PublishTime 
                { 
                        get {  return _publishTime; } 
                        set { _publishTime = value; } 
                } 
        } 
}

using System; 
using System.Collections.Generic; 
using System.Text; 
 
namespace Pattern.Command 
{ 
         /// <summary> 
         /// enum 
         /// 定义操作的两种方法Insert和Delete 
         /// </summary> 
         public  enum Action 
        { 
                 /// <summary> 
                 /// Insert 
                 /// </summary> 
                Insert, 
 
                 /// <summary> 
                 /// Delete 
                 /// </summary> 
                Delete 
        } 
}

using System; 
using System.Collections.Generic; 
using System.Text; 
 
namespace Pattern.Command 
{ 
         /// <summary> 
         /// 接收者（Receiver）角色 
         /// Sql方式操作Message 
         /// </summary> 
         public  class SqlMessage 
        { 
                 /// <summary> 
                 /// 操作 
                 /// </summary> 
                 /// <param name="action">操作的方法</param> 
                 /// <param name="mm">Message实体对象</param> 
                 public  void Operation(Action action, MessageModel mm) 
                { 
                         switch (action) 
                        { 
                                 case Action.Insert :    
                                        Insert(mm);    
                                         break; 
                                 case Action.Delete : 
                                        Delete(mm); 
                                         break; 
                        } 
                } 
 
                 /// <summary> 
                 /// 插入Message 
                 /// </summary> 
                 /// <param name="mm">Message实体对象</param> 
                 private  void Insert(MessageModel mm) 
                { 
                         // 代码略 
                } 
 
                 /// <summary> 
                 /// 删除Message 
                 /// </summary> 
                 /// <param name="mm">Message实体对象</param> 
                 private  void Delete(MessageModel mm) 
                { 
                         // 代码略 
                } 
        } 
}

using System; 
using System.Collections.Generic; 
using System.Text; 
 
namespace Pattern.Command 
{ 
         /// <summary> 
         /// 命令（Command）角色 
         /// </summary> 
         public  interface ICommand 
        { 
                 /// <summary> 
                 /// 执行 
                 /// </summary> 
                 /// <returns>操作的方法及操作的信息</returns> 
                 string Execute(); 
 
                 /// <summary> 
                 /// 取消执行 
                 /// </summary> 
                 /// <returns>操作的方法及操作的信息</returns> 
                 string UnExecute(); 
        } 
}

using System; 
using System.Collections.Generic; 
using System.Text; 
 
namespace Pattern.Command 
{ 
         /// <summary> 
         /// 具体命令（ConcreteCommand）角色 
         /// </summary> 
         public  class SqlMessageCommand : ICommand 
        { 
                 /// <summary> 
                 /// 操作的方法 
                 /// </summary> 
                 private Action _action; 
 
                 /// <summary> 
                 /// Message实体对象 
                 /// </summary> 
                 private MessageModel _mm; 
 
                 /// <summary> 
                 /// 构造函数 
                 /// </summary> 
                 /// <param name="action">操作的方法</param> 
                 /// <param name="mm">Message实体对象</param> 
                 public SqlMessageCommand(Action action, MessageModel mm) 
                { 
                         this._action = action; 
                         this._mm = mm; 
                } 
 
                 /// <summary> 
                 /// 执行 
                 /// </summary> 
                 /// <returns>操作的方法及操作的信息</returns> 
                 public  string Execute() 
                { 
                         new SqlMessage().Operation(_action, _mm); 
 
                         return _action.ToString() +  "：" + _mm.Message; 
                } 
 
                 /// <summary> 
                 /// 取消执行（调用一个方法，以决定取消执行的算法） 
                 /// </summary> 
                 /// <returns>操作的方法及操作的信息</returns> 
                 public  string UnExecute() 
                { 
                        _action = GetUndoAction(_action); 
                         new SqlMessage().Operation(_action, _mm); 
 
                         return _action.ToString() +  "：" + _mm.Message; 
                } 
 
                 /// <summary> 
                 /// 获得取消执行的算法 
                 /// </summary> 
                 /// <param name="action">操作的方法</param> 
                 /// <returns></returns> 
                 private Action GetUndoAction(Action action) 
                { 
                        Action undo; 
 
                         switch (action) 
                        { 
                                 case Action.Insert :    
                                        undo = Action.Delete;    
                                         break; 
                                 case Action.Delete : 
                                        undo = Action.Insert; 
                                         break; 
                                 // 这句没啥用 
                                 default : 
                                        undo = Action.Insert; 
                                         break; 
                        } 
 
                         return undo; 
                } 
        } 
}

using System; 
using System.Collections.Generic; 
using System.Text; 
 
namespace Pattern.Command 
{ 
         /// <summary> 
         /// 请求者（Invoker）角色 
         /// </summary> 
         public  class Message 
        { 
                 /// <summary> 
                 /// 命令集合（保存每次操作） 
                 /// </summary> 
                 private List<ICommand> _listCommand =  new List<ICommand>(); 
 
                 /// <summary> 
                 /// 命令集合中当前要执行的命令的索引 
                 /// </summary> 
                 private  int current = 0; 
 
                 /// <summary> 
                 /// 执行Sql 
                 /// </summary> 
                 /// <param name="action">操作的方法</param> 
                 /// <param name="mm">Message实体对象</param> 
                 /// <returns>操作的方法及操作的信息</returns> 
                 public  string Do(Action action, MessageModel mm) 
                { 
                         string rtn = ""; 
 
                        ICommand cmd =  new SqlMessageCommand(action, mm); 
                        rtn = cmd.Execute(); 
 
                        _listCommand.Add(cmd); 
                        current++; 
 
                         return rtn; 
                } 
 
                 /// <summary> 
                 /// 撤销 
                 /// </summary> 
                 /// <param name="levels">执行撤销操作的次数</param> 
                 /// <returns>操作的方法及操作的信息（用空格分开多条记录）</returns> 
                 public  string Undo( int levels) 
                { 
                         string rtn = ""; 
 
                         for ( int i = 0; i < levels; i++) 
                        { 
                                 if (current > 0) 
                                { 
                                        ICommand cmd = _listCommand[--current]; 
                                        rtn += cmd.UnExecute() +  " "; 
                                } 
                        } 
 
                         return rtn; 
                } 
 
                 /// <summary> 
                 /// 重复 
                 /// </summary> 
                 /// <param name="levels">执行重复操作的次数</param> 
                 /// <returns>操作的方法及操作的信息（用空格分开多条记录）</returns> 
                 public  string Redo( int levels) 
                { 
                         string rtn = ""; 
 
                         for ( int i = 0; i < levels; i++) 
                        { 
                                 if (current < _listCommand.Count - 1) 
                                { 
                                        ICommand cmd = _listCommand[current++]; 
                                        rtn += cmd.UnExecute() +  " "; 
                                } 
                        } 
 
                         return rtn; 
                } 
        } 
}

using System; 
using System.Data; 
using System.Configuration; 
using System.Collections; 
using System.Web; 
using System.Web.Security; 
using System.Web.UI; 
using System.Web.UI.WebControls; 
using System.Web.UI.WebControls.WebParts; 
using System.Web.UI.HtmlControls; 
 
using Pattern.Command; 
 
public partial  class Command : System.Web.UI.Page 
{ 
         protected  void Page_Load( object sender, EventArgs e) 
        { 
                Message m =  new Message(); 
 
                Response.Write( "操作"); 
                Response.Write( "<br />"); 
                Response.Write(m.Do(Action.Insert,  new MessageModel( "第1条", DateTime.Now))); 
                Response.Write( "<br />"); 
                Response.Write(m.Do(Action.Insert,  new MessageModel( "第2条", DateTime.Now))); 
                Response.Write( "<br />"); 
                Response.Write(m.Do(Action.Insert,  new MessageModel( "第3条", DateTime.Now))); 
                Response.Write( "<br />"); 
                Response.Write(m.Do(Action.Insert,  new MessageModel( "第4条", DateTime.Now))); 
                Response.Write( "<br />"); 
                Response.Write(m.Do(Action.Delete,  new MessageModel( "第2条", DateTime.Now))); 
                Response.Write( "<br />"); 
                Response.Write(m.Do(Action.Insert,  new MessageModel( "第5条", DateTime.Now))); 
                Response.Write( "<br />"); 
                Response.Write(m.Do(Action.Delete,  new MessageModel( "第3条", DateTime.Now))); 
                Response.Write( "<br />"); 
                Response.Write(m.Do(Action.Insert,  new MessageModel( "第6条", DateTime.Now))); 
                Response.Write( "<br />"); 
                Response.Write(m.Do(Action.Insert,  new MessageModel( "第7条", DateTime.Now))); 
                Response.Write( "<br />"); 
                Response.Write( "<br />"); 
 
                Response.Write( "撤销4次操作"); 
                Response.Write( "<br />"); 
                Response.Write(m.Undo(4)); 
                Response.Write( "<br />"); 
                Response.Write( "<br />"); 
 
                Response.Write( "重复2次操作"); 
                Response.Write( "<br />"); 
                Response.Write(m.Redo(2)); 
                Response.Write( "<br />"); 
                Response.Write( "<br />"); 
 
                Response.Write( "撤销3次操作"); 
                Response.Write( "<br />"); 
                Response.Write(m.Undo(3)); 
        } 
}