作者: slightboy, 时间: 2006-10-14
首发于: http://cs.alienwave.cn/Topic/329.aspx
看到好多同学权限判断都是用字符串 然后或分割或截取
其实对于 允许/不允许(true/false) 这种的权限, 用逻辑运算再恰当不过了
声明下: 本文针对入门和为掌握的同学, 如果已经懂了那可以无视了
可能意思表达的不是很清楚, 敬请原谅.
逻辑运算符介绍:
And: 逻辑与
0 And 0 = 0
0 And 1 = 0
1 And 0 = 0
1 And 1 = 1
Or: 逻辑或
0 Or 0 = 0
0 Or 1 = 1
1 Or 0 = 1
1 Or 1 = 1
Xor: 异或
0 Xor 0 = 1
0 Xor 1 = 1
1 Xor 0 = 1
1 Xor 1 = 1
Not: 逻辑非
Not 1 = 0
Not 0 = 1
表达方式介绍:
1 表示 ture, 0 表示 false
举二位为例
第一位 表示 Read 的权限, 第二位 表示 Write 的权限, 可以表示一下四种权限
00 Read(false) Write(false)
01 Read(true) Write(false)
10 Read(false) Write(true)
11 Read(true) Write(true)
运算方式介绍:
还是继续上面的例子
Read = 01(1), Write = 10(2)
00(0) And Read = 0
01(1) And Read = Read
10(2) And Read = 0
11(3) And Read = Read
00(0) And Write = 0
01(1) And Write = 0
10(2) And Write = Write
11(3) And Write = Write
下面给出示例代码:
权限定义类(要有枚举类型该多好啊...)
Class PermissionTypePublic ReadPublic WritePublic DeletePrivate Sub Class_InitializeRead = 1Write = 2Delete = 4End SubEnd Class
权限类
Class PermissionSetComponentPrivate intValuePublic Property Get Read()Read = GetValue(Permission.Read)End PropertyPublic Property Let Read(arg)Call SetValue(Permission.Read, arg)End PropertyPublic Property Get Write()Write = GetValue(Permission.Write)End PropertyPublic Property Let Write(arg)Call SetValue(Permission.Write, arg)End PropertyPublic Property Get Delete()Delete = GetValue(Permission.Delete)End PropertyPublic Property Let Delete(arg)Call SetValue(Permission.Delete, arg)End PropertyPublic Property Get Value()Value = intValueEnd PropertyPublic Property Let Value(arg)intValue = argEnd PropertyPublic Function GetValue(intType)GetValue = (Value and intType) = intTypeEnd FunctionPublic Sub SetValue(intType, boolValue)IF (boolValue) ThenValue = Value Or intTypeElseValue = Value And (Not intType)End IFEnd SubEnd Class
运用示例代码:
Dim Permission : Set Permission = new PermissionTypeDim PermissionSet : Set PermissionSet = new PermissionSetComponentPermissionSet.Value = 0w("Read:")PermissionSet.Read = falsew(PermissionSet.Value &" "& PermissionSet.Read)PermissionSet.Read = truew(PermissionSet.Value &" "& PermissionSet.Read)w("Write:")PermissionSet.Write = falsew(PermissionSet.Value &" "& PermissionSet.Write)PermissionSet.Write = truew(PermissionSet.Value &" "& PermissionSet.Write)w("Delete:")PermissionSet.Delete = falsew(PermissionSet.Value &" "& PermissionSet.Delete)PermissionSet.Delete = truew(PermissionSet.Value &" "& PermissionSet.Delete)Function w(o)Response.Write("<br />"& o)End Function
今天的课程就到这里, 大家可以举一反三, 下课...