我需要实时将上传的二进制文件转换为base64字符串格式。我正在使用ASP和Vbscript,使用Midori的组件进行base64转换。对于小型文件(<20K),性能还可以。 但当超过75或100K时,完全失效。有没有有效的方法将大型二进制文件(2MB)转换为base64字符串格式?
谢谢, 肯尼
谢谢, 肯尼
Function ToBase64(rabyt)
Dim xml: Set xml = CreateObject("MSXML2.DOMDocument.3.0")
xml.LoadXml "<root />"
xml.documentElement.dataType = "bin.base64"
xml.documentElement.nodeTypedValue = rabyt
ToBase64 = xml.documentElement.Text
End Function
请注意,这将在base64编码中包含换行符,但大多数base64解码器都能容忍换行符。如果不能容忍,您可以简单地使用Replace(base64, vbLF, "")
来删除它们,这仍然比纯VBScript解决方案更快。
编辑 示例用法:
Dim sBase64: sBase64 = ToBase64(Request.BinaryRead(Request.TotalBytes))
你应该使用.NET方法Convert.ToBase64String和Convert.FromBase64String。
使用Convert.FromBase64String()方法。这将返回二进制数据(作为字节数组)。
要将二进制数据转换为Base64字符串,请参见vbscript中从二进制数据到字符串的转换函数
来自http://www.motobit.com/tips/detpg_Base64Encode/
Function Base64EncodeBinary(inData)
Base64EncodeBinary = Base64Encode(BinaryToString(inData))
End Function
Function Base64Encode(inData)
'rfc1521
'2001 Antonin Foller, Motobit Software, http://Motobit.cz
Const Base64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
Dim cOut, sOut, I
'For each group of 3 bytes
For I = 1 To Len(inData) Step 3
Dim nGroup, pOut, sGroup
'Create one long from this 3 bytes.
nGroup = &H10000 * Asc(Mid(inData, I, 1)) + _
&H100 * MyASC(Mid(inData, I + 1, 1)) + MyASC(Mid(inData, I + 2, 1))
'Oct splits the long To 8 groups with 3 bits
nGroup = Oct(nGroup)
'Add leading zeros
nGroup = String(8 - Len(nGroup), "0") & nGroup
'Convert To base64
pOut = Mid(Base64, CLng("&o" & Mid(nGroup, 1, 2)) + 1, 1) + _
Mid(Base64, CLng("&o" & Mid(nGroup, 3, 2)) + 1, 1) + _
Mid(Base64, CLng("&o" & Mid(nGroup, 5, 2)) + 1, 1) + _
Mid(Base64, CLng("&o" & Mid(nGroup, 7, 2)) + 1, 1)
'Add the part To OutPut string
sOut = sOut + pOut
'Add a new line For Each 76 chars In dest (76*3/4 = 57)
'If (I + 2) Mod 57 = 0 Then sOut = sOut + vbCrLf
Next
Select Case Len(inData) Mod 3
Case 1: '8 bit final
sOut = Left(sOut, Len(sOut) - 2) + "=="
Case 2: '16 bit final
sOut = Left(sOut, Len(sOut) - 1) + "="
End Select
Base64Encode = sOut
End Function
Function MyASC(OneChar)
If OneChar = "" Then MyASC = 0 Else MyASC = Asc(OneChar)
End Function
我使用以下代码进行c#编程:
public static string ImageToBase64(Image image, ImageFormat format)
{
using (MemoryStream ms = new MemoryStream())
{
// Convert Image to byte[]
image.Save(ms, format);
byte[] imageBytes = ms.ToArray();
// Convert byte[] to Base64 String
string base64String = Convert.ToBase64String(imageBytes);
return base64String;
}
}
public static Image Base64ToImage(string base64String)
{
// Convert Base64 String to byte[]
byte[] imageBytes = Convert.FromBase64String(base64String);
MemoryStream ms = new MemoryStream(imageBytes, 0,
imageBytes.Length);
// Convert byte[] to Image
ms.Write(imageBytes, 0, imageBytes.Length);
Image image = Image.FromStream(ms, true);
return image;
}
如果您需要VBScript,可以查看http://www.freevbcode.com/ShowCode.asp?ID=5248,或许能帮到您。
在base64-encode-string-in-vbscript中有一个很好的讨论。
此外,我发现this site对于尝试从vb代码中提取速度非常有用。那里有几个vb6的base 64变体,速度相当快。
这是对我有效的方法
Function Base64DataURI(url)
'Create an Http object, use any of the four objects
Dim Http
Set Http = CreateObject("WinHttp.WinHttpRequest.5.1")
'Send request To URL
Http.Open "GET", url, False
Http.Send
'Get response data As a string and encode as base64
Base64DataURI = Encrypt(Http.ResponseText)
End Function