ASP基础之内置类型及注意点

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发布时间：2019-06-09

本文共 8981 字，大约阅读时间需要 29 分钟。

我记得:

初学时,经常对Request的类型迷惑

初学时,经常对Request.Form的类型迷惑

初学时,经常对Request.Form("id")的类型迷惑

初学时,经常对.item, .items, .count, .content的表达迷惑不已.

其实,说不清道不明的原因还是自己太懒惰了,资料查得少,查得略,查得3心2意,自然失过错过.

很简单的事情 :

1 <%  2 On Error Resume Next  3 Dim i,biName,arrBI,AI  4 biName = "ObjectContext," &_  5          "Server," &_  6          "Application," &_  7          "Application.Contents," &_  8          "Application.StaticObjects," &_  9          "Session," &_ 10          "Session.Contents," &_ 11          "Session.StaticObjects," &_ 12          "Request," &_ 13          "Response," &_ 14          "Server.GetLastError," &_ 15          "Request.ServerVariables," &_ 16          "Request.ClientCertificate," &_ 17          "Request.Cookies," &_ 18          "Request.Form," &_ 19          "Request.QueryString," &_ 20          "Response," &_ 21          "Response.Cookies," &_ 22          "Request.Form(""ID"")," &_ 23          "Request.QueryString(""ID"")," &_ 24          "Request.Cookies(""ID"")," &_ 25          "Request.ClientCertificate(""Subject"")," &_ 26          "Request.ServerVariables(""URL"")," &_ 27          "Server.CreateObject(""ADODB.Connection"")," &_ 28          "Server.CreateObject(""ADODB.Recordset"")," &_ 29          "Server.CreateObject(""Scripting.FileSystemObject"")," &_ 30          "Server.CreateObject(""Scripting.Dictionary"")" 31          32 arrBI = Split(biName,",") 33 Response.Write("TrueTrueTrueTrue
     
       "& _ 34 "
" &_ 35 "
" &_ 36 "
" & vbNewLine) 38 39 For i = 0 To Ubound(arrBI) 40     Set AI = Eval(arrBI(i)) 41     Response.Write("
") 45     46     47     If Err > 0 Then Err.Clear 48     Dim v,hasItem,hasItems 49     hasItem = False 50     hasItems = False 51     hasContents = False 52     hasCount = False 53     54     v = TypeName(AI("0")) 55     If Err > 0 Then 56         Err.Clear 57     Else 58         hasItem = "" 59     End If 60     61     v = TypeName(AI.Items) 62     If Err > 0 Then 63         Err.Clear 64     Else 65         hasItems = "" 66     End If 67     68     v = TypeName(AI.Contents) 69     If Err > 0 Then 70         Err.Clear 71     Else 72         hasContents = "" 73     End If 74     75     76     v = TypeName(AI.Count) 77     If Err > 0 Then 78         Err.Clear 79     Else 80         hasCount = "" 81     End If 82     83     Response.Write("
" & vbNewLine)    87     88 Next 89 Response.Write("
                     TypeName操作         TypeName结果         是否有" &_ 37 "Items,Item,Contents,Count属性        
               " &_ 42                    ""&arrBI(i)&"<"&"/"& _ 43                    "span>          " &_ 44                    " "&TypeName(AI)&"         item:"& hasItem&" | " &_ 84                         "items:"& hasItems&" | " &_ 85                         "contents:"& hasContents&" | " &_ 86                         "count:"& hasCount&"        
      
     
" & vbNewLine) 90 %>

TypeName操作	TypeName结果	是否有" &_ 37 "Items,Item,Contents,Count属性
" &_ 42 ""&arrBI(i)&"<"&"/"& _ 43 "span>	" &_ 44 " "&TypeName(AI)&"	item:"& hasItem&" \| " &_ 84 "items:"& hasItems&" \| " &_ 85 "contents:"& hasContents&" \| " &_ 86 "count:"& hasCount&"

输出结果:

TypeName操作	TypeName结果	是否有Items,Item,Contents,Count属性
ObjectContext	IASPObjectContext	item:False \| items:False \| contents:False \| count:False
Server	IServer	item:False \| items:False \| contents:False \| count:False
Application	IApplicationObject	item:True \| items:False \| contents:True \| count:False
Application.Contents	IVariantDictionary	item:True \| items:False \| contents:False \| count:True
Application.StaticObjects	IVariantDictionary	item:True \| items:False \| contents:False \| count:True
Session	ISessionObject	item:True \| items:False \| contents:True \| count:False
Session.Contents	IVariantDictionary	item:True \| items:False \| contents:False \| count:True
Session.StaticObjects	IVariantDictionary	item:True \| items:False \| contents:False \| count:True
Request	IRequest	item:True \| items:False \| contents:False \| count:False
Response	IResponse	item:False \| items:False \| contents:False \| count:False
Server.GetLastError	IASPError	item:False \| items:False \| contents:False \| count:False
Request.ServerVariables	IRequestDictionary	item:True \| items:False \| contents:False \| count:True
Request.ClientCertificate	IRequestDictionary	item:True \| items:False \| contents:False \| count:True
Request.Cookies	IRequestDictionary	item:True \| items:False \| contents:False \| count:True
Request.Form	IRequestDictionary	item:True \| items:False \| contents:False \| count:True
Request.QueryString	IRequestDictionary	item:True \| items:False \| contents:False \| count:True
Response	IResponse	item:False \| items:False \| contents:False \| count:False
Response.Cookies	IRequestDictionary	item:True \| items:False \| contents:False \| count:True
Request.Form("ID")	IStringList	item:True \| items:False \| contents:False \| count:True
Request.QueryString("ID")	IStringList	item:True \| items:False \| contents:False \| count:True
Request.Cookies("ID")	IReadCookie	item:True \| items:False \| contents:False \| count:True
Request.ClientCertificate("Subject")	IRequestDictionary	item:True \| items:False \| contents:False \| count:True
Request.ServerVariables("URL")	IStringList	item:True \| items:False \| contents:False \| count:True
Server.CreateObject("ADODB.Connection")	Connection	item:False \| items:False \| contents:False \| count:False
Server.CreateObject("ADODB.Recordset")	Recordset	item:False \| items:False \| contents:False \| count:False
Server.CreateObject("Scripting.FileSystemObject")	FileSystemObject	item:False \| items:False \| contents:False \| count:False
Server.CreateObject("Scripting.Dictionary")	Dictionary	item:True \| items:True \| contents:False \| count:True

备注:

1.对于Request.Form,Request.QueryString,类型为 IRequestDictionary,它们是集合对象,它(们)拥有Item属性及Count方法.

对于Item,这里有参考部分:

Item 属性

展示集合中指定的项目。

.Item()

参数

Object

EnumNetworkDrive 或 EnumPrinterConnections 方法的结果，或者由 Environment 或 SpecialFolders 属性返回的对象。

natIndex

要检索的项目。

说明

Item 是每个集合的默认属性。对于 EnumNetworkDrive 和 EnumPrinterConnections 集合来说，索引是一个整数；对 Environment 和 SpecialFolders 集合来说，索引是一个字符串。

如果请求的文件夹 (strFolderName) 不可用，则 WshShell.SpecialFolders.Item (strFolderName) 在 VBScript 中返回 "Empty"，而在 JScript 中返回 "undefined"。

在这里,对于Request.Form(及Request.QueryString),当被用于输出,+-*/等操作时(TypeName,VarType等特殊类型操作除外),它相当于Request.Form.Item()(及Request.QueryString.Item()).它们相应返回接收到的参数字符串

如果要获取查询参数当中有多少个参数,可以如下代码:

<% Dim itemKey,itemVal For Each itemKey In Request.QueryString     itemVal = Request.QueryString.Item(itemKey) '或:Request.QueryString(itemKey)     Response.Write(itemKey & ": " & itemVal & "
" & vbNewLine) Next %>

2.对于Request.Form("id")(及Request.QueryString("id")),类型为 IStringList,它们也是集合对象,它(们)拥有Item属性及Count方法.

如果要获取查询参数当中ID参数项,用以下代码是严重错误的:

<% Dim itemKey,itemVal For Each itemKey In Request.QueryString.Item("id")     itemVal = Request.QueryString.Item("id").Item(itemKey) '或:Request.QueryString("id")(itemKey)     Response.Write(itemKey & ": " & itemVal & "
" & vbNewLine) Next %>

它不能正确输出各项.因为For each...Next语句对IRequestDictionary及IStringList的元素解析不一样,正确的代码为:

<% Dim itemKey,itemVal,iItem For iItem = 1 To Request.QueryString.Item("id").Count     itemKey = iItem     itemVal = Request.QueryString.Item("id").Item(itemKey) '或:Request.QueryString("id")(itemKey)     Response.Write(itemKey & ": " & itemVal & "
" & vbNewLine) Next %>

可见,Request.QueryString及Request.QueryString("id")在key-value方面有着差别.

前者:以各个接收的参数名分别作为item的key名.用for each ... next可正确枚举

后者:从1到count分别作为item的key名.用for each...next不可正确枚举(或不雅观),可用for ..to..next及count结合解决

至此,item,count及返回类型方面的归结暂时停止...

然后,对于item(),还有一些简写及其说明必须交代一下:

以下代码执行效果一样:

<% Response.Write "
" & Request.QueryString Response.Write "
" & Request.QueryString() Response.Write "
" & Request.QueryString.Item Response.Write "
" & Request.QueryString.Item() %>

以下代码执行效果一样:

<% Response.Write "
" & Request.QueryString("id") Response.Write "
" & Request.QueryString("id")() Response.Write "
" & Request.QueryString("id").Item Response.Write "
" & Request.QueryString("id").Item() Response.Write "
" & Request.QueryString.Item("id") Response.Write "
" & Request.QueryString.Item("id").Item Response.Write "
" & Request.QueryString.Item("id").Item() %>

以下代码执行效果一样:

<% Response.Write "
" & Request.QueryString.Count Response.Write "
" & Request.QueryString().Count %>

以下代码执行效果一样:

<% Response.Write "
" & Request.QueryString("id").Count Response.Write "
" & Request.QueryString.Item("id").Count %>

值得注意的地方:不要以下的错误的代码写法:

<% Response.Write "
" & Request.QueryString.Item.Count Response.Write "
" & Request.QueryString.Item().Count Response.Write "
" & Request.QueryString("id").Item.Count Response.Write "
" & Request.QueryString.Item("id").Item().Count %>

即item及item()之后不能接.Count,而item("id")或不用item时才能接.Count

因为不管IRequestDictionary还是IStringList,其Item()的结果为字符串了,不能再进行count调用

Request.QueryString.Item()其结果为所有的查询参数串成的字符串

Request.QueryString.Item("id").Item()或Reuqest.QueryString("id").Item()其结果为所有的查询参数为ID的参数名值串成的字符串

其它:Dictionary字典对象集合才有Items()方法,不要与item()或item(key)弄混.

字典的items()方法将返回一个变量数组,以结合for .. to .. next和Ubound()操作

字典同时还有item及count属性

字典符合For each...next操作

Application及Session当中还有类似Item的Contents属性,返回集合对象IVariantDictionary.操作性等同于IRequestDictionary

Application及Session当中还有Item属性,真的吗？？？（当然不是,是验证函数的问题！！）

本文参考：

＜＜Windows脚本技术＞＞　