一种简单的直观的高效的权限设计
大部分系统都有权限系统。一般来说，它能管控人员对某个否页面的访问；对某些字段、控件可见或者不可见。对gridview中的数据是否可删除、可添加、可新增等等。大部分人都把权限作为一个子系统独立出来。但是这里我不是想设计一个权限管理系统，网上的设计方案太多了，可以说每个开发人员都有自己的开发权限管理系统的想法和思路。
在这篇文章中，我先用简单的C#代码模仿一个用户的权限，再使用sql去模拟。这是一种很简单，很直观，很高效的方式去判定用户的权限。
C#:
好吧，先从最简单开始，定义一个用户（User）类，如下。
1
class
User
2 {
3 bool CanDelete;
4 bool CanRead;
5 bool CanWrite;
6 bool CanModify;
7 bool CanCreate;
8 }
2 {
3 bool CanDelete;
4 bool CanRead;
5 bool CanWrite;
6 bool CanModify;
7 bool CanCreate;
8 }
这里设计5个属性来管控用户的权限。我发现这样虽然很直观，但是不宜扩张。我们将权限独立出来，在看下面代码：
1
enum
PermissionTypes :
int
2 {
3 None = 0 ,
4 Read = 1 ,
5 Write = 2 ,
6 Modify = 4 ,
7 Delete = 8 ,
8 Create = 16 ,
9 All = Read | Write | Modify | Delete | Create
10 }
11 class User
12 {
13 public PermissionTypes Permissions = PermissionTypes.None;
14 }
2 {
3 None = 0 ,
4 Read = 1 ,
5 Write = 2 ,
6 Modify = 4 ,
7 Delete = 8 ,
8 Create = 16 ,
9 All = Read | Write | Modify | Delete | Create
10 }
11 class User
12 {
13 public PermissionTypes Permissions = PermissionTypes.None;
14 }
我们先试用一下，你就能感觉到神奇之处：
1
//
创建一个用户
2 User admin = new User();
3 admin.Permissions = PermissionTypes.Read
4 | PermissionTypes.Write
5 | PermissionTypes.Delete;
6
7 // 验证权限
8 bool canRead = ((PermissionTypes.Read & admin.Permissions) == PermissionTypes.Read);
9 bool canWrite = ((PermissionTypes.Write & admin.Permissions) == PermissionTypes.Write);
10 bool canCreate = ((PermissionTypes.Create & admin.Permissions) == PermissionTypes.Create);
11
12 // 查看结果
13 Console.WriteLine(canRead); // true
14 Console.WriteLine(canWrite); // true
15 Console.WriteLine(canCreate); // false
16
2 User admin = new User();
3 admin.Permissions = PermissionTypes.Read
4 | PermissionTypes.Write
5 | PermissionTypes.Delete;
6
7 // 验证权限
8 bool canRead = ((PermissionTypes.Read & admin.Permissions) == PermissionTypes.Read);
9 bool canWrite = ((PermissionTypes.Write & admin.Permissions) == PermissionTypes.Write);
10 bool canCreate = ((PermissionTypes.Create & admin.Permissions) == PermissionTypes.Create);
11
12 // 查看结果
13 Console.WriteLine(canRead); // true
14 Console.WriteLine(canWrite); // true
15 Console.WriteLine(canCreate); // false
16
利用了'|'和'&'两个操作。但是这样看起来很是很别捏，初始化权限和验证权限用了一长串'|'和'&'运算的代码。很不直观。我在System.Enum中扩展一些方法供你调用，代码如下。
1
//
是否存在权限
2 public static bool Has < T > ( this System.Enum type, T value)
3 {
4 try
5 {
6 return ((( int )( object )type & ( int )( object )value) == ( int )( object )value);
7 }
8 catch
9 {
10 return false ;
11 }
12 }
13 // 判断权限
14 public static bool Is < T > ( this System.Enum type, T value)
15 {
16 try
17 {
18 return ( int )( object )type == ( int )( object )value;
19 }
20 catch
21 {
22 return false ;
23 }
24 }
25 // 添加权限
26 public static T Add < T > ( this System.Enum type, T value)
27 {
28 try
29 {
30 return (T)( object )((( int )( object )type | ( int )( object )value));
31 }
32 catch (Exception ex)
33 {
34 throw new ArgumentException(
35 string .Format(
36 " 不能添加类型 '{0}' " ,
37 typeof (T).Name
38 ), ex);
39 }
40 }
41
42 // 移除权限
43 public static T Remove < T > ( this System.Enum type, T value)
44 {
45 try
46 {
47 return (T)( object )((( int )( object )type & ~ ( int )( object )value));
48 }
49 catch (Exception ex)
50 {
51 throw new ArgumentException(
52 string .Format(
53 " 不能移除类型 '{0}' " ,
54 typeof (T).Name
55 ), ex);
56 }
57 }
2 public static bool Has < T > ( this System.Enum type, T value)
3 {
4 try
5 {
6 return ((( int )( object )type & ( int )( object )value) == ( int )( object )value);
7 }
8 catch
9 {
10 return false ;
11 }
12 }
13 // 判断权限
14 public static bool Is < T > ( this System.Enum type, T value)
15 {
16 try
17 {
18 return ( int )( object )type == ( int )( object )value;
19 }
20 catch
21 {
22 return false ;
23 }
24 }
25 // 添加权限
26 public static T Add < T > ( this System.Enum type, T value)
27 {
28 try
29 {
30 return (T)( object )((( int )( object )type | ( int )( object )value));
31 }
32 catch (Exception ex)
33 {
34 throw new ArgumentException(
35 string .Format(
36 " 不能添加类型 '{0}' " ,
37 typeof (T).Name
38 ), ex);
39 }
40 }
41
42 // 移除权限
43 public static T Remove < T > ( this System.Enum type, T value)
44 {
45 try
46 {
47 return (T)( object )((( int )( object )type & ~ ( int )( object )value));
48 }
49 catch (Exception ex)
50 {
51 throw new ArgumentException(
52 string .Format(
53 " 不能移除类型 '{0}' " ,
54 typeof (T).Name
55 ), ex);
56 }
57 }
使用一下：
1
//
创建一个用户
2 User admin = new User();
3 PermissionTypes permissions = new PermissionTypes();
4 admin.Permissions = permissions;
5 // 添加权限
6 admin.Permissions = admin.Permissions.Add(PermissionTypes.Create);
7 admin.Permissions = admin.Permissions.Add(PermissionTypes.Read);
8 admin.Permissions = admin.Permissions.Add(PermissionTypes.Write);
9 // 判断权限
10 bool canRead = admin.Permissions.Has(PermissionTypes.Read); // true
11 bool canWrite = admin.Permissions.Has(PermissionTypes.Write); // true
12 bool canDelete = admin.Permissions.Has(PermissionTypes.Delete); // false
13 bool canCreate = admin.Permissions.Has(PermissionTypes.Create); // true
14
15 Console.WriteLine(canRead); // true
16 Console.WriteLine(canWrite); // true
17 Console.WriteLine(canDelete); // false
18 Console.WriteLine(canCreate); // true
19 Console.Read();
2 User admin = new User();
3 PermissionTypes permissions = new PermissionTypes();
4 admin.Permissions = permissions;
5 // 添加权限
6 admin.Permissions = admin.Permissions.Add(PermissionTypes.Create);
7 admin.Permissions = admin.Permissions.Add(PermissionTypes.Read);
8 admin.Permissions = admin.Permissions.Add(PermissionTypes.Write);
9 // 判断权限
10 bool canRead = admin.Permissions.Has(PermissionTypes.Read); // true
11 bool canWrite = admin.Permissions.Has(PermissionTypes.Write); // true
12 bool canDelete = admin.Permissions.Has(PermissionTypes.Delete); // false
13 bool canCreate = admin.Permissions.Has(PermissionTypes.Create); // true
14
15 Console.WriteLine(canRead); // true
16 Console.WriteLine(canWrite); // true
17 Console.WriteLine(canDelete); // false
18 Console.WriteLine(canCreate); // true
19 Console.Read();
SQL：
大部分权限管理都是数据库的操作，好依照上面的思路，我在sqlserver里面模拟一下以上的操作,在sql中与或运算是很高效的。先设计两张表User和Permission。
1、获取有Read权限的所有用户：
1
select
*
from
[
User
]
where
PermissionTypes
&
1
=
1
Result:
2、获取有Delete权限的所有用户：
1
select
*
from
[
User
]
where
PermissionTypes
&
8
=
8
Result:
3、判断麒麟是否有有Delete权限
1
if
exists
(
select
*
from
[
User
]
where
Name
=
'
qilin
'
and
PermissionTypes
&
8
=
8
)
2 print ' true '
3 else
4 print ' flase '
2 print ' true '
3 else
4 print ' flase '
Result: flase
本文转自麒麟博客园博客，原文链接：http://www.cnblogs.com/zhuqil/archive/2010/04/02/Permission.html，如需转载请自行联系原作者
