C# Enum 简易权限设计 使用FlagsAttribute属性
C# Enum 简易权限设计 使用FlagsAttribute属性
基本权限设计：
/// <summary>
/// 权限列举
/// </summary>
[FlagsAttribute]
public enum Permissions
{
[Description("未设定")]
None = 0,
[Description("建立")]
Create = 1,
[Description("读取")]
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
