最近整理ASP/VBScript代碼，發(fā)現(xiàn)過(guò)去的一個(gè)ASP實(shí)現(xiàn)的MVC框架，可惜是個(gè)半成品，效率也成問(wèn)題，不過(guò)發(fā)現(xiàn)里面有些我寫(xiě)的代碼，感覺(jué)還稍稍可以拿出來(lái)見(jiàn)人，于是今天作此文以記之。
說(shuō)是ASP，其實(shí)和VBScript也脫不了干系，VBScript語(yǔ)言傳承于Visual Basic，VB的語(yǔ)法靈活度已經(jīng)不盡如人意了，VBS作為其子集可想而知。神馬反射、自省等先進(jìn)的技術(shù)，微軟在.NET中才引入。作為被拋棄的技術(shù)，也不奢望微軟能夠提供支持，于是頑固守舊的程序員只有絞盡腦汁的去模仿實(shí)現(xiàn)一些類(lèi)似的功能。
好吧，我承認(rèn)很長(zhǎng)一段時(shí)間我就是頑固守舊派中的一員，今天介紹的就是其中的一項(xiàng)功能，動(dòng)態(tài)創(chuàng)建一個(gè)屬性對(duì)象，屬性對(duì)象姑且這么稱(chēng)呼，也就是說(shuō)動(dòng)態(tài)創(chuàng)建的對(duì)象只包含屬性(Properties)。
下面貼出實(shí)現(xiàn)代碼供大家參考：
復(fù)制代碼 代碼如下:
'
' ASP/VBScript Dynamic Object Generator
' Author: WangYe
' For more information please visit
'
' This code is distributed under the BSD license
'
Const PROPERTY_ACCESS_READONLY = 1
Const PROPERTY_ACCESS_WRITEONLY = -1
Const PROPERTY_ACCESS_ALL = 0
Class DynamicObject
Private m_objProperties
Private m_strName
Private Sub Class_Initialize()
Set m_objProperties = CreateObject("Scripting.Dictionary")
m_strName = "AnonymousObject"
End Sub
Private Sub Class_Terminate()
If Not IsObject(m_objProperties) Then
m_objProperties.RemoveAll
End If
Set m_objProperties = Nothing
End Sub
Public Sub setClassName(strName)
m_strName = strName
End Sub
Public Sub add(key, value, access)
m_objProperties.Add key, Array(value, access)
End Sub
Public Sub setValue(key, value, access)
If m_objProperties.Exists(key) Then
m_objProperties.Item(key)(0) = value
m_objProperties.Item(key)(1) = access
Else
add key,value,access
End If
End Sub
Private Function getReadOnlyCode(strKey)
Dim strPrivateName, strPublicGetName
strPrivateName = "m_var" strKey
strPublicGetName = "get" strKey
getReadOnlyCode = _
"Public Function " strPublicGetName "() :" _
strPublicGetName "=" strPrivateName " : " _
"End Function : Public Property Get " strKey _
" : " strKey "=" strPrivateName " : End Property : "
End Function
Private Function getWriteOnlyCode(strKey)
Dim pstr
Dim strPrivateName, strPublicSetName, strParamName
strPrivateName = "m_var" strKey
strPublicSetName = "set" strKey
strParamName = "param" strKey
getWriteOnlyCode = _
"Public Sub " strPublicSetName "(" strParamName ") :" _
strPrivateName "=" strParamName " : " _
"End Sub : Public Property Let " strKey "(" strParamName ")" _
" : " strPrivateName "=" strParamName " : End Property : "
End Function
Private Function parse()
Dim i, Keys, Items
Keys = m_objProperties.Keys
Items = m_objProperties.Items
Dim init, pstr
init = ""
pstr = ""
parse = "Class " m_strName " :" _
"Private Sub Class_Initialize() : "
Dim strPrivateName
For i = 0 To m_objProperties.Count - 1
strPrivateName = "m_var" Keys(i)
init = init strPrivateName "=""" _
Replace(CStr(Items(i)(0)), """", """""") """:"
pstr = pstr "Private " strPrivateName " : "
If CInt(Items(i)(1)) > 0 Then ' ReadOnly
pstr = pstr getReadOnlyCode(Keys(i))
ElseIf CInt(Items(i)(1)) 0 Then ' WriteOnly
pstr = pstr getWriteOnlyCode(Keys(i))
Else ' AccessAll
pstr = pstr getReadOnlyCode(Keys(i)) _
getWriteOnlyCode(Keys(i))
End If
Next
parse = parse init "End Sub : " pstr "End Class"
End Function
Public Function getObject()
Call Execute(parse)
Set getObject = Eval("New " m_strName)
End Function
Public Sub invokeObject(ByRef obj)
Call Execute(parse)
Set obj = Eval("New " m_strName)
End Sub
End Class
對(duì)于屬性對(duì)象分別提供了Property直接訪問(wèn)模式和set或者get函數(shù)訪問(wèn)模式，當(dāng)然我還提供了三種權(quán)限控制，在add方法中使用，分別是PROPERTY_ACCESS_READONLY（屬性只讀）、PROPERTY_ACCESS_WRITEONLY（屬性只寫(xiě)）和PROPERTY_ACCESS_ALL（屬性讀寫(xiě)），你可以像下面這樣使用（一個(gè)例子）：
復(fù)制代碼 代碼如下:
Dim DynObj
Set DynObj = New DynamicObject
DynObj.add "Name", "WangYe", PROPERTY_ACCESS_READONLY
DynObj.add "HomePage", "http://jb51.net", PROPERTY_ACCESS_READONLY
DynObj.add "Job", "Programmer", PROPERTY_ACCESS_ALL
'
' 如果沒(méi)有setClassName，
' 新創(chuàng)建的對(duì)象將會(huì)自動(dòng)命名為AnonymousObject
' 但是如果創(chuàng)建多個(gè)對(duì)象，就必須指定名稱(chēng)
' 否則就可能引起對(duì)象名重復(fù)的異常
DynObj.setClassName "User"
Dim User
Set User = DynObj.GetObject()
' 或者 DynObj.invokeObject User
Response.Write User.Name
' Response.Write User.getName()
Response.Write User.HomePage
' Response.Write User.getHomePage()
Response.Write User.Job
' Response.Write User.getJob()
' 改變屬性值
User.Job = "Engineer"
' User.setJob "Engineer"
Response.Write User.getJob()
Set User = Nothing
Set DynObj = Nothing
其原理很簡(jiǎn)單，就是通過(guò)給定的Key-Value動(dòng)態(tài)生成VBS Class腳本代碼，然后調(diào)用Execute執(zhí)行以便于將這段代碼加入到代碼上下文流中，最后再通過(guò)Eval新建這個(gè)對(duì)象。
好了，就介紹到這里，今后我可能還會(huì)陸續(xù)公開(kāi)一些Classic ASP的相關(guān)技巧代碼。
2012年11月7日更新
修復(fù)從舊項(xiàng)目移植過(guò)來(lái)導(dǎo)致的BUG。
修復(fù)了一些Bug增加了一些特性，我先把最新的代碼貼出來(lái)供大家參考：
復(fù)制代碼 代碼如下:
'
' ASP/VBScript Dynamic Object Generator
' Author: WangYe
' For more information please visit
'
' This code is distributed under the BSD license
'
' UPDATE:
' 2012/11/7
' 1. Add variable key validator.
' 2. Add hasattr_ property for determine
' if the property exists.
' 3. Add getattr_ property for get property
' value safety.
' 4. Class name can be accessed by ClassName_ property.
' 5. Fixed some issues.
'
Const PROPERTY_ACCESS_READONLY = 1
Const PROPERTY_ACCESS_WRITEONLY = -1
Const PROPERTY_ACCESS_ALL = 0
Class DynamicObject
Private m_objProperties
Private m_strName
Private m_objRegExp
Private Sub Class_Initialize()
Set m_objProperties = CreateObject("Scripting.Dictionary")
Set m_objRegExp = New RegExp
m_objRegExp.IgnoreCase = True
m_objRegExp.Global = False
m_objRegExp.Pattern = "^[a-z][a-z0-9]*$"
m_strName = "AnonymousObject"
m_objProperties.Add "ClassName_", _
Array(m_strName, PROPERTY_ACCESS_READONLY)
End Sub
Private Sub Class_Terminate()
Set m_objRegExp = Nothing
If IsObject(m_objProperties) Then
m_objProperties.RemoveAll
End If
Set m_objProperties = Nothing
End Sub
Public Sub setClassName(strName)
If Not m_objRegExp.Test(strName) Then
' Skipped Invalid Class Name
' Raise
Exit Sub
End If
m_strName = strName
m_objProperties("ClassName_") = _
Array(m_strName, PROPERTY_ACCESS_READONLY)
End Sub
Public Sub add(key, value, access)
If Not m_objRegExp.Test(key) Then
' Skipped Invalid key
' Raise
Exit Sub
End If
If key = "hasattr_" Then key = "hasattr__"
If key = "ClassName_" Then key = "ClassName__"
'Response.Write key
m_objProperties.Add key, Array(value, access)
End Sub
Public Sub setValue(key, value, access)
If m_objProperties.Exists(key) Then
m_objProperties.Item(key)(0) = value
m_objProperties.Item(key)(1) = access
Else
add key,value,access
End If
End Sub
Private Function getReadOnlyCode(strKey)
Dim strPrivateName, strPublicGetName
strPrivateName = "m_var" strKey
strPublicGetName = "get" strKey
getReadOnlyCode = _
"Public Function " strPublicGetName "() :" _
strPublicGetName "=" strPrivateName " : " _
"End Function : Public Property Get " strKey _
" : " strKey "=" strPrivateName _
" : End Property : "
End Function
Private Function getWriteOnlyCode(strKey)
Dim pstr
Dim strPrivateName, strPublicSetName, strParamName
strPrivateName = "m_var" strKey
strPublicSetName = "set" strKey
strParamName = "param" strKey
getWriteOnlyCode = _
"Public Sub " strPublicSetName _
"(" strParamName ") :" _
strPrivateName "=" strParamName " : " _
"End Sub : Public Property Let " strKey _
"(" strParamName ")" _
" : " strPrivateName "=" strParamName _
" : End Property : "
End Function
Private Function parse()
Dim i, Keys, Items
Keys = m_objProperties.Keys
Items = m_objProperties.Items
Dim init, pstr
init = ""
pstr = ""
parse = "Class " m_strName " :" _
"Private Sub Class_Initialize() : "
Dim strPrivateName, strAvailableKeys
For i = 0 To m_objProperties.Count - 1
strPrivateName = "m_var" Keys(i)
init = init strPrivateName "=""" _
Replace(CStr(Items(i)(0)), """", """""") """:"
pstr = pstr "Private " strPrivateName " : "
strAvailableKeys = strAvailableKeys Keys(i) ","
If CInt(Items(i)(1)) > 0 Then ' ReadOnly
pstr = pstr getReadOnlyCode(Keys(i))
ElseIf CInt(Items(i)(1)) 0 Then ' WriteOnly
pstr = pstr getWriteOnlyCode(Keys(i))
Else ' AccessAll
pstr = pstr getReadOnlyCode(Keys(i)) _
getWriteOnlyCode(Keys(i))
End If
Next
init = init "m_strAvailableKeys = Replace(""," _
strAvailableKeys """, "" "", """") : "
Dim hasstmt
hasstmt = "Private m_strAvailableKeys : " _
"Public Function hasattr_(ByVal key) : " _
"hasattr_ = CBool(InStr(m_strAvailableKeys," _
" "","" key "","") > 0) : " _
"End Function : " _
"Public Function getattr_(ByVal key, ByVal defaultValue) : " _
"If hasattr_(key) Then : getattr_ = Eval(key) : " _
"Else : getattr_ = defaultValue : End If : " _
"End Function : "
parse = parse init "End Sub : " _
hasstmt pstr "End Class"
End Function
Public Function getObject()
'Response.Write parse
Call Execute(parse)
Set getObject = Eval("New " m_strName)
End Function
Public Sub invokeObject(ByRef obj)
Call Execute(parse)
Set obj = Eval("New " m_strName)
End Sub
End Class
需要注意的幾個(gè)新特性：
1. 增加了類(lèi)名和屬性名驗(yàn)證措施，防止畸形的類(lèi)名或者屬性名導(dǎo)致動(dòng)態(tài)生成的代碼出現(xiàn)語(yǔ)法錯(cuò)誤。不過(guò)處理的方式是直接忽略，本來(lái)想Raise異常的，但考慮到VBS對(duì)異常處理不是很好的，所以采取忽略策略：
' 有效的類(lèi)名或?qū)傩悦仨氁宰帜搁_(kāi)頭
復(fù)制代碼 代碼如下:
Dim DynObj
Set DynObj = New DynamicObject
DynObj.setClassName "1User" ' 此句將被忽略，因?yàn)轭?lèi)名不能以數(shù)字開(kāi)始
' 下面這句也會(huì)被忽略，因?yàn)閷傩悦荒芤蕴厥夥?hào)開(kāi)始
DynObj.add "%Name", "WangYe", PROPERTY_ACCESS_READONLY
Set DynObj = Nothing
2. 對(duì)于動(dòng)態(tài)對(duì)象增加了hasattr_方法，該屬性用于檢測(cè)此對(duì)象是否支持相應(yīng)的屬性，可以在訪問(wèn)一個(gè)屬性前先確定該對(duì)象是否支持此屬性：
復(fù)制代碼 代碼如下:
Dim DynObj
Set DynObj = New DynamicObject
DynObj.add "Name", "WangYe", PROPERTY_ACCESS_READONLY
Response.Write DynObj.hasattr_("Name") ' True
Response.Write DynObj.hasattr_("Favor") ' False
Set DynObj = Nothing
3. 對(duì)于動(dòng)態(tài)對(duì)象增加了getattr_方法，此方法可以安全的獲取指定的屬性值，避免因?yàn)閷?duì)象不存在屬性值導(dǎo)致出錯(cuò)。方法原型為getattr_(ByVal propertyName, ByVal defaultValue)，參數(shù)propertyName指定屬性的名字，defaultValue是當(dāng)指定屬性不存在是可以返回的默認(rèn)值，比如下面代碼：
復(fù)制代碼 代碼如下:
Dim DynObj
Set DynObj = New DynamicObject
DynObj.add "Name", "WangYe", PROPERTY_ACCESS_READONLY
Response.Write DynObj.getattr_("Name", "N/A") ' WangYe
Response.Write DynObj.getattr_("Favor", "N/A") ' N/A
Set DynObj = Nothing
4. 動(dòng)態(tài)對(duì)象的類(lèi)名可以通過(guò)ClassName_屬性或者getClassName_()方法獲取。
2012年11月12日更新
修復(fù)雙引號(hào)導(dǎo)致構(gòu)造類(lèi)錯(cuò)誤或?qū)е聢?zhí)行任意代碼的Bug。
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