至少有三種以上辦法，可以把二進制數(shù)據(jù)（比如您從ASP的Request.BinaryRead方法得到的數(shù)據(jù)）轉(zhuǎn)換為字符串。
第一種：使用VBS的MultiByte 方法
實例：
Function SimpleBinaryToString(Binary)
'SimpleBinaryToString converts binary data (VT_UI1 | VT_ARRAY Or MultiByte string)
'to a string (BSTR) using MultiByte VBS functions
Dim I, S
For I = 1 To LenB(Binary)
S = S & Chr(AscB(MidB(Binary, I, 1)))
Next
SimpleBinaryToString = S
End Function
這個方法非常簡單明了，但是處理大數(shù)據(jù)流時，比較慢。
建議只用來處理100KB以下的數(shù)據(jù)。
下面的這個類似的方法，性能稍微好些：
Function BinaryToString(Binary)
'Antonin Foller, http://www.pstruh.cz
'Optimized version of a simple BinaryToString algorithm.
Dim cl1, cl2, cl3, pl1, pl2, pl3
Dim L
cl1 = 1
cl2 = 1
cl3 = 1
L = LenB(Binary)
Do While cl1<=L
pl3 = pl3 & Chr(AscB(MidB(Binary,cl1,1)))
cl1 = cl1 + 1
cl3 = cl3 + 1
If cl3>300 Then
pl2 = pl2 & pl3
pl3 = ""
cl3 = 1
cl2 = cl2 + 1
If cl2>200 Then
pl1 = pl1 & pl2
pl2 = ""
cl2 = 1
End If
End If
Loop
BinaryToString = pl1 & pl2 & pl3
End Function
BinaryToString方法比SimpleBinaryToString方法性能高20倍。建議用來處理2MB以下的數(shù)據(jù)。
第二種方法：使用ADODB.Recordset
ADODB.Recordset 可以讓你支持幾乎所有VARIANT支持的數(shù)據(jù)類型，你可以用它在string和
binary之間轉(zhuǎn)換。
Function RSBinaryToString(xBinary)
'Antonin Foller, http://www.pstruh.cz
'RSBinaryToString converts binary data (VT_UI1 | VT_ARRAY Or MultiByte string)
'to a string (BSTR) using ADO recordset
Dim Binary
'MultiByte data must be converted To VT_UI1 | VT_ARRAY first.
If vartype(xBinary)=8 Then Binary = MultiByteToBinary(xBinary) Else Binary = xBinary
Dim RS, LBinary
Const adLongVarChar = 201
Set RS = CreateObject("ADODB.Recordset")
LBinary = LenB(Binary)
If LBinary>0 Then
RS.Fields.Append "mBinary", adLongVarChar, LBinary
RS.Open
RS.AddNew
RS("mBinary").AppendChunk Binary
RS.Update
RSBinaryToString = RS("mBinary")
Else
RSBinaryToString = ""
End If
End Function
RSBinaryToString 沒有什么限制--除了物理內(nèi)存之外。這種處理方式是MultiByte方式的100倍！你可以用它來處理高達(dá)100MB的數(shù)據(jù)！ 這種轉(zhuǎn)換方式，你也可以用來把MultiByte strings轉(zhuǎn)換為String。下面這個方法把MultiByte strings轉(zhuǎn)換為Binary：Function MultiByteToBinary(MultiByte)
'© 2000 Antonin Foller, http://www.pstruh.cz
' MultiByteToBinary converts multibyte string To real binary data (VT_UI1 | VT_ARRAY)
' Using recordset
Dim RS, LMultiByte, Binary
Const adLongVarBinary = 205
Set RS = CreateObject("ADODB.Recordset")
LMultiByte = LenB(MultiByte)
If LMultiByte>0 Then
RS.Fields.Append "mBinary", adLongVarBinary, LMultiByte
RS.Open
RS.AddNew
RS("mBinary").AppendChunk MultiByte & ChrB(0)
RS.Update
Binary = RS("mBinary").GetChunk(LMultiByte)
End If
MultiByteToBinary = Binary
End Function
第三種：使用ADODB.Stream這種方式是比較常用的：'Stream_BinaryToString Function
'2003 Antonin Foller, http://www.pstruh.cz
'Binary - VT_UI1 | VT_ARRAY data To convert To a string
'CharSet - charset of the source binary data - default is "us-ascii"
Function Stream_BinaryToString(Binary, CharSet)
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 = adTypeBinary
'Open the stream And write text/string data To the object
BinaryStream.Open
BinaryStream.Write Binary
'Change stream type To binary
BinaryStream.Position = 0
BinaryStream.Type = adTypeText
'Specify charset For the source text (unicode) data.
If Len(CharSet) > 0 Then
BinaryStream.CharSet = CharSet
Else
BinaryStream.CharSet = "us-ascii"
End If
'Open the stream And get binary data from the object
Stream_BinaryToString = BinaryStream.ReadText
End Function
要存儲、獲取二進制數(shù)據(jù)，從一個本地文件、上傳的二進制數(shù)據(jù)文件或者ASP中，可以參考：Pure and Huge ASP file upload with progress.。 Tip keywords: Binary, Byte, Array, VT_UI1, VT_ARRAY, BinaryWrite, BinaryRead, ChrB, InstrB, LeftB, MidB, RightB, ASP, VBSCOPYRIGHT AND PERMITTED USE OF http://www.pstruh.cz/tips WEBSITE. The entire contents of PSTRUH Software website consist of copyright material owned by Antonin Foller, PSTRUH Software.
