C# Enum 简易权限设计 使用FlagsAttribute属性

基本權限設計：

/// <summary>

/// 權限列舉

/// </summary>

[FlagsAttribute]

public enum Permissions

{

    [Description("未設定")]

    None = 0,

    [Description("建立")]

    Create = 1,

    [Description("讀取")]

    Read = 2,

    [Description("更新")]

    Update = 4,

    [Description("刪除")]

    Delete = 8,

    [Description("所有功能")]

    All = Create | Read | Update | Delete

}

技巧一：利用 2 的次方值，來作為列舉值以便日後做位元運算  ( & AND、 | OR、 ^ XOR)。

技巧二：現有權限中，加入新權限動作。(OR 運算)

Permissions permission = Permissions.None;

permission = permission | Permissions.Create;

MessageBox.Show(permission.ToString());

// Result: Create

技巧三：加入【FlagsAttribute】標籤

Permissions permission = Permissions.None;

permission = permission | Permissions.Create;

MessageBox.Show(permission.ToString());

// Result: Create ([FlagsAttribute]不影響結果)

permission = permission | Permissions.Read;

MessageBox.Show(permission.ToString());

// Result: 3 (未加入[FlagsAttribute])

// Result: Create, Read (加入[FlagsAttribute])

技巧四：現有權限中，移除某個權限動作。( XOR 與 AND 運算應用)

Permissions permission = Permissions.None;

permission = permission | Permissions.Create;

MessageBox.Show(permission.ToString());

// Result: Create

permission = permission | Permissions.Read;

permission = permission | Permissions.Update;

MessageBox.Show(permission.ToString());

// Result: Create, Read, Update

permission = (permission & (Permissions.All ^ Permissions.Read));

MessageBox.Show(permission.ToString());

// Result: Create, Update

技巧五：判斷現在權限中，是否擁有某個權限 (AND 運算)

Permissions permission = Permissions.None;

permission = permission | Permissions.Create;

MessageBox.Show(permission.ToString());

// Result: Create

permission = permission | Permissions.Read;

permission = permission | Permissions.Update;

MessageBox.Show(permission.ToString());

// Result: Create, Read, Update

permission = (permission & (Permissions.All ^ Permissions.Read));

MessageBox.Show(permission.ToString());

// Result: Create, Update

bool IsCreatable = false;

if((permission & Permissions.Create) == Permissions.Create)

{

    IsCreatable = true;

}

else

{

    IsCreatable = false;

}

MessageBox.Show(IsCreatable.ToString());

// Result: True

簡易權限類別設計：

   1:  /// <summary>

   2:  /// 我的權限

   3:  /// </summary>

   4:  public class MyPermission

   5:  {

   6:      private Permissions _permission;

   7:      private bool _isCreatable = false;

   8:      private bool _isReadable = false;

   9:      private bool _isUpdatable = false;

  10:      private bool _isDeletable = false;

  11:   

  12:      /// <summary>

  13:      /// 權限

  14:      /// </summary>

  15:      public Permissions Permission

  16:      {

  17:          get { return _permission; }

  18:          set

  19:          {

  20:              _permission = value;

  21:   

  22:              IsCreatable = ((value & Permissions.Create) == Permissions.Create) ? true : false;

  23:              IsReadable = ((value & Permissions.Read) == Permissions.Read) ? true : false;

  24:              IsUpdatable = ((value & Permissions.Update) == Permissions.Update) ? true : false;

  25:              IsDeletable = ((value & Permissions.Delete) == Permissions.Delete) ? true : false;

  26:          }

  27:      }

  28:   

  29:      /// <summary>

  30:      /// 是否可建立?

  31:      /// </summary>

  32:      public bool IsCreatable

  33:      {

  34:          get { return _isCreatable; }

  35:          set

  36:          {

  37:              _isCreatable = value;

  38:   

  39:              if (value)

  40:              {

  41:                  AddPermissionFlag(Permissions.Create);

  42:              }

  43:              else

  44:              {

  45:                  RemovePermissionFlag(Permissions.Create);

  46:              }

  47:          }

  48:      }

  49:   

  50:      /// <summary>

  51:      /// 是否可讀?

  52:      /// </summary>

  53:      public bool IsReadable

  54:      {

  55:          get { return _isReadable; }

  56:          set 

  57:          {

  58:              _isReadable = value;

  59:   

  60:              if (value)

  61:              {

  62:                  AddPermissionFlag(Permissions.Read);

  63:              }

  64:              else

  65:              {

  66:                  RemovePermissionFlag(Permissions.Read);

  67:              }

  68:          }

  69:      }

  70:   

  71:      /// <summary>

  72:      /// 是否可新增?

  73:      /// </summary>

  74:      public bool IsUpdatable

  75:      {

  76:          get { return _isUpdatable; }

  77:          set

  78:          {

  79:              _isUpdatable = value;

  80:   

  81:              if (value)

  82:              {

  83:                  AddPermissionFlag(Permissions.Update);

  84:              }

  85:              else

  86:              {

  87:                  RemovePermissionFlag(Permissions.Update);

  88:              }

  89:          }

  90:      }

  91:   

  92:      /// <summary>

  93:      /// 是否可刪除?

  94:      /// </summary>

  95:      public bool IsDeletable

  96:      {

  97:          get { return _isDeletable; }

  98:          set

  99:          {

 100:              _isDeletable = value;

 101:   

 102:              if (value)

 103:              {

 104:                  AddPermissionFlag(Permissions.Delete);

 105:              }

 106:              else

 107:              {

 108:                  RemovePermissionFlag(Permissions.Delete);

 109:              }

 110:          }

 111:      }

 112:   

 113:      /// <summary>

 114:      /// 現有權限中增加某個權限

 115:      /// </summary>

 116:      /// <param name="addFlag">某個權限</param>

 117:      public void AddPermissionFlag (Permissions addFlag)

 118:      {

 119:          _permission = _permission | addFlag;

 120:      }

 121:   

 122:      /// <summary>

 123:      /// 現有權限中移除某個權限

 124:      /// </summary>

 125:      /// <param name="removeFlag">某權限</param>

 126:      public void RemovePermissionFlag (Permissions removeFlag)

 127:      {

 128:          _permission = (_permission & (Permissions.All ^ removeFlag));    

 129:      }

 130:  }

簡易權限類別使用：

   1:  MyPermission mp = new MyPermission();

   2:   

   3:  mp.Permission = Permissions.Create;

   4:  // Create

   5:  MessageBox.Show(mp.Permission.ToString());

   6:   

   7:  mp.AddPermissionFlag(Permissions.Read);

   8:  // Create, Read

   9:  MessageBox.Show(mp.Permission.ToString());

  10:   

  11:  mp.IsUpdatable = true;

  12:  // Create, Read, Update

  13:  MessageBox.Show(mp.Permission.ToString());

  14:   

  15:  mp.IsDeletable = true;

  16:  // All

  17:  MessageBox.Show(mp.Permission.ToString());

  18:   

  19:  mp.RemovePermissionFlag(Permissions.Delete);

  20:  // Create, Read, Update

  21:  MessageBox.Show(mp.Permission.ToString());

  22:   

  23:  mp.IsUpdatable = false;

  24:  // Create, Read

  25:  MessageBox.Show(mp.Permission.ToString());

 

from:http://www.dotblogs.com.tw/chhuang/archive/2008/04/26/3514.aspx