vb6 的 base64转换

VB6 中可以使用 Microsoft XML Core Services (MSXML) 提供的 Base64 编码和解码功能。以下是一个示例代码：

Private Function Base64Encode(ByVal sText As String) As String
    Dim xmlDoc As MSXML2.DOMDocument60
    Dim nodeElem As MSXML2.IXMLDOMElement

    Set xmlDoc = New MSXML2.DOMDocument60
    Set nodeElem = xmlDoc.createElement("b64")

    nodeElem.DataType = "bin.base64"
    nodeElem.nodeTypedValue = Stream_StringToBinary(sText)

    Base64Encode = nodeElem.Text

    Set nodeElem = Nothing
    Set xmlDoc = Nothing
End Function

Private Function Base64Decode(ByVal sText As String) As String
    Dim xmlDoc As MSXML2.DOMDocument60
    Dim nodeElem As MSXML2.IXMLDOMElement

    Set xmlDoc = New MSXML2.DOMDocument60
    Set nodeElem = xmlDoc.createElement("b64")

    nodeElem.DataType = "bin.base64"
    nodeElem.Text = sText

    Base64Decode = Stream_BinaryToString(nodeElem.nodeTypedValue)

    Set nodeElem = Nothing
    Set xmlDoc = Nothing
End Function

Private Function Stream_StringToBinary(ByVal sText As String) As Variant
    Dim Stream As ADODB.Stream

    Set Stream = New ADODB.Stream

    Stream.Open
    Stream.Type = adTypeText
    Stream.Charset = "utf-8"
    Stream.WriteText sText
    Stream.Position = 0
    Stream.Type = adTypeBinary
    Stream_StringToBinary = Stream.Read
    Stream.Close

    Set Stream = Nothing
End Function

Private Function Stream_BinaryToString(ByVal vBinary As Variant) As String
    Dim Stream As ADODB.Stream

    Set Stream = New ADODB.Stream

    Stream.Open
    Stream.Type = adTypeBinary
    Stream.Write vBinary
    Stream.Position = 0
    Stream.Type = adTypeText
    Stream.Charset = "utf-8"
    Stream_BinaryToString = Stream.ReadText
    Stream.Close

    Set Stream = Nothing
End Function

使用示例：

Dim sText As String
Dim sBase64 As String
Dim sDecoded As String

sText = "Hello, world!"

sBase64 = Base64Encode(sText)
MsgBox sBase64

sDecoded = Base64Decode(sBase64)
MsgBox sDecoded