encoding - 在 VBScript 中对字符串进行 Base64 编码

Question

我有一个 Web 服务加载驱动程序，它是 Windows 脚本文件 (WSF)，其中包括一些 VBScript 和 JavaScript 文件。我的 Web 服务要求传入消息采用 Base64 编码。我目前有一个 VBScript 函数可以执行此操作，但效率非常低(内存密集型，主要是由于 VBScript 糟糕的字符串连接)

[旁白；是的，我见过Jeff's latest blog post 。连接发生在大小为 1,000 到 10,000 字节的消息之间的循环中。]

我尝试过使用一些自定义字符串连接例程；一种使用数组，一种使用 ADODB.Stream。这些有一点帮助，但我认为如果我有其他方法来编码消息而不是通过我自己的 VBS 函数，会更有帮助。

是否有其他方式对我的消息进行编码，最好使用 native Windows 方法？

Answer 1

我最初使用的是 Antonin Foller 的一些 VBScript 代码: Base64 Encode VBS Function和 Base64 Decode VBS Function 。

搜索 Antonin 的网站，我看到他有一些 quoted printable encoding, using the CDO.Message object 的代码，所以我尝试了。

最后，我将Mark的回答中提到的代码移植到VBScript(还使用了this SO问题中的一些代码)，并使用了Stream___StringToBinary和 Stream_BinaryToString来自 Antonin 网站的函数来获取使用 MSXML 编码的函数。

我进行了一项快速测试，测量所有四种方法中 1,500 个字符消息的编码时间(我需要发送到网络服务的平均消息大小):

• native VBScript (VBScript)
• 引用可打印，使用 CDO.Message (QP)
• 引用的可打印二进制文件，使用 CDO.Message(QP 二进制文件)
• MSXML/ADODB.Stream (MSXML)

结果如下:

Iterations   : 10,000
Message Size :  1,500

+-------------+-----------+
+ Method      | Time (ms) + 
+-------------+-----------+
| VBScript    |   301,391 |
+-------------+-----------+
| QP          |    12,922 |
+-------------+-----------+
| QP (Binary) |    13,953 |
+-------------+-----------+
| MSXML       |     3,312 |
+-------------+-----------+

I also monitored the memory utilization (Mem Usage for the cscript.exe process in the Windows Task Manager) while the test was running. I don't have any raw numbers, but the memory utilization for both the quoted printable and MSXML solutions were below the VBScript solution (7,000K for the former, around 16,000K for VBScript).

I decided to go with the MSXML solution for my driver. For those interested, here's the code I'm using:

base64.vbs
Function Base64Encode(sText)
    Dim oXML, oNode

    Set oXML = CreateObject("Msxml2.DOMDocument.3.0")
    Set oNode = oXML.CreateElement("base64")
    oNode.dataType = "bin.base64"
    oNode.nodeTypedValue =Stream_StringToBinary(sText)
    Base64Encode = oNode.text
    Set oNode = Nothing
    Set oXML = Nothing
End Function

Function Base64Decode(ByVal vCode)
    Dim oXML, oNode

    Set oXML = CreateObject("Msxml2.DOMDocument.3.0")
    Set oNode = oXML.CreateElement("base64")
    oNode.dataType = "bin.base64"
    oNode.text = vCode
    Base64Decode = Stream_BinaryToString(oNode.nodeTypedValue)
    Set oNode = Nothing
    Set oXML = Nothing
End Function

'Stream_StringToBinary Function
'2003 Antonin Foller, http://www.motobit.com
'Text - string parameter To convert To binary data
Function Stream_StringToBinary(Text)
  Const adTypeText = 2
  Const adTypeBinary = 1

  'Create Stream object
  Dim BinaryStream 'As New Stream
  Set BinaryStream = CreateObject("ADODB.Stream")

  'Specify stream type - we want To save text/string data.
  BinaryStream.Type = adTypeText

  'Specify charset For the source text (unicode) data.
  BinaryStream.CharSet = "us-ascii"

  'Open the stream And write text/string data To the object
  BinaryStream.Open
  BinaryStream.WriteText Text

  'Change stream type To binary
  BinaryStream.Position = 0
  BinaryStream.Type = adTypeBinary

  'Ignore first two bytes - sign of
  BinaryStream.Position = 0

  'Open the stream And get binary data from the object
  Stream_StringToBinary = BinaryStream.Read

  Set BinaryStream = Nothing
End Function

'Stream_BinaryToString Function
'2003 Antonin Foller, http://www.motobit.com
'Binary - VT_UI1 | VT_ARRAY data To convert To a string 
Function Stream_BinaryToString(Binary)
  Const adTypeText = 2
  Const adTypeBinary = 1

  'Create Stream object
  Dim BinaryStream 'As New Stream
  Set BinaryStream = CreateObject("ADODB.Stream")

  'Specify stream type - we want To save binary data.
  BinaryStream.Type = adTypeBinary

  'Open the stream And write binary data To the object
  BinaryStream.Open
  BinaryStream.Write Binary

  'Change stream type To text/string
  BinaryStream.Position = 0
  BinaryStream.Type = adTypeText

  'Specify charset For the output text (unicode) data.
  BinaryStream.CharSet = "us-ascii"

  'Open the stream And get text/string data from the object
  Stream_BinaryToString = BinaryStream.ReadText
  Set BinaryStream = Nothing
End Function