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：

/// <summary>
/// 我的權限
/// </summary>
public class MyPermission
{
    private Permissions _permission;
    private bool _isCreatable = false;
    private bool _isReadable = false;
    private bool _isUpdatable = false;
    private bool _isDeletable = false;

    /// <summary>
    /// 權限
    /// </summary>
    public Permissions Permission
    {
        get { return _permission; }
        set
        {
            _permission = value;

            IsCreatable = ((value & Permissions.Create) == Permissions.Create) ? true : false;
            IsReadable = ((value & Permissions.Read) == Permissions.Read) ? true : false;
            IsUpdatable = ((value & Permissions.Update) == Permissions.Update) ? true : false;
            IsDeletable = ((value & Permissions.Delete) == Permissions.Delete) ? true : false;
        }
    }

    /// <summary>
    /// 是否可建立?
    /// </summary>
    public bool IsCreatable
    {
        get { return _isCreatable; }
        set
        {
            _isCreatable = value;

            if (value)
            {
                AddPermissionFlag(Permissions.Create);
            }
            else
            {
                RemovePermissionFlag(Permissions.Create);
            }
        }
    }

    /// <summary>
    /// 是否可讀?
    /// </summary>
    public bool IsReadable
    {
        get { return _isReadable; }
        set
        {
            _isReadable = value;

            if (value)
            {
                AddPermissionFlag(Permissions.Read);
            }
            else
            {
                RemovePermissionFlag(Permissions.Read);
            }
        }
    }

    /// <summary>
    /// 是否可新增?
    /// </summary>
    public bool IsUpdatable
    {
        get { return _isUpdatable; }
        set
        {
            _isUpdatable = value;

            if (value)
            {
                AddPermissionFlag(Permissions.Update);
            }
            else
            {
                RemovePermissionFlag(Permissions.Update);
            }
        }
    }

    /// <summary>
    /// 是否可刪除?
    /// </summary>
    public bool IsDeletable
    {
        get { return _isDeletable; }
        set
        {
            _isDeletable = value;

            if (value)
            {
                AddPermissionFlag(Permissions.Delete);
            }
            else
            {
                RemovePermissionFlag(Permissions.Delete);
            }
        }
    }

    /// <summary>
    /// 現有權限中增加某個權限
    /// </summary>
    /// <param name="addFlag">某個權限</param>
    public void AddPermissionFlag (Permissions addFlag)
    {
        _permission = _permission | addFlag;
    }

    /// <summary>
    /// 現有權限中移除某個權限
    /// </summary>
    /// <param name="removeFlag">某權限</param>
    public void RemovePermissionFlag (Permissions removeFlag)
    {
        _permission = (_permission & (Permissions.All ^ removeFlag));
    }
}

簡易權限類別使用：

MyPermission mp = new MyPermission();

mp.Permission = Permissions.Create;
// Create
MessageBox.Show(mp.Permission.ToString());

mp.AddPermissionFlag(Permissions.Read);
// Create, Read
MessageBox.Show(mp.Permission.ToString());

mp.IsUpdatable = true;
// Create, Read, Update
MessageBox.Show(mp.Permission.ToString());

mp.IsDeletable = true;
// All
MessageBox.Show(mp.Permission.ToString());

mp.RemovePermissionFlag(Permissions.Delete);
// Create, Read, Update
MessageBox.Show(mp.Permission.ToString());

mp.IsUpdatable = false;
// Create, Read
MessageBox.Show(mp.Permission.ToString());

 

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