[VBS]转换二进制数据为字符串常用办法

至少有三种以上办法,可以把二进制数据(比如您从ASP的Request.BinaryRead方法得到的数据)转换为字符串。

第一种:使用VBS的MultiByte 方法

实例:

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 = SEnd Function
这个方法非常简单明了,但是处理大数据流时,比较慢。
建议只用来处理100KB以下的数据。
下面的这个类似的方法,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 & pl3End Function
BinaryToString方法比SimpleBinaryToString方法性能高20倍。
建议用来处理2MB以下的数据。
第二种方法:使用ADODB.Recordset
ADODB.Recordset 可以让你支持几乎所有VARIANT支持的数据类型,你可以用它在string和
binary之间转换。
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 IfEnd FunctionRSBinaryToString 没有什么限制--除了物理内存之外。
这种处理方式是MultiByte方式的100倍!
你可以用它来处理高达100MB的数据!
 
这种转换方式,你也可以用来把MultiByte strings转换为String。下面这个
方法把MultiByte strings转换为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 = BinaryEnd Function
第三种:使用ADODB.Stream
这种方式是比较常用的:
'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.ReadTextEnd Function
要存储、获取二进制数据,从一个本地文件、上传的二进制数据文件或者ASP中,可以参考:
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, VBS
    
      

COPYRIGHT 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.
 
郑昀兼做翻译。转贴请注明出处。


Trackback: http://tb.blog.csdn.net/TrackBack.aspx?PostId=12758


你可能感兴趣的:(字符串)