) C # Use bitwise operations to manage permissions

Common bitwise operations include (&), (|), and (~), For example:

1 & 0 = 0, 1 | 0 = 1 ,~ 1 = 0

When designing the permission, we can convert the permission operation into bitwise operations for processing.

Step 1: Create an enumeration to indicate all permission operations:

 
[Flags]
 

 
Public EnumPermissions
 

 
{
 

 
Insert = 1,
 

 
Delete = 2,
 

 
Update = 4,
 

 
Query = 8
 

 
}
 

[Flags] indicates that this enumeration can support bitwise operations. For each enumerated value, we use the Npower of 2 to assign a value. In this way, the value is 1 = 0001 in binary format, 2 = 0010, 4 = 0100, 8 = 1000, etc. Each digit indicates a permission. 1 indicates that the permission is granted, and 0 indicates that no.

Next is the permission calculation:

1.Permission AdditionWe know that 0001 | 0100 = 0101, which means that both the First and Third BITs have the permissions, and the enumerated values are:

 
Permissions per = permissions. Insert | permissions. Update
 

2.Permission Subtraction, And is implemented using operations + non-operations. If you want to remove the insert permission above, the operation is:

 
Permissions per & = ~ Permissions. insert
 

That is, 0101 &~ 0001 = 0101 & 1110 = 0100

3.Permission judgmentWhen determining whether a user has the operation permission, the user's permission and operation permission should be performed and calculated. If the result is still the operation permission, indicates that the user has this permission:

Permissions per = permissions. Insert | permissions. update;If(Per & permissions. Insert = permissions. insert ){// Operation permission}
 

 
When the comparison process is 0101 & 0001 = 0001,000, the 0 bits of 1 are set to 0 and the other bits are compared to the 1 bits.
 

 
From: http://www.cnblogs.com/xiaosonl/archive/2009/06/17/1505312.html