Question

VB编程中如何将UTF-8和Unicode互相转换？

本人相菜鸟，希望注释下哦，还有用法。 VB编程中如何将UTF-8编码和Unicode编码互相转换？把UTF-8转码成Unicode的，和把UTF-8转成Unicode.....

Answer 1

'Utf8 转换为 Unicode
Public Function UTF8_Decode(ByVal s As String) As String
Dim lUtf8Size As Long
Dim sBuffer As String
Dim lBufferSize As Long
Dim lResult As Long
Dim b() As Byte
If LenB(s) Then
On Error GoTo EndFunction
b = StrConv(s, vbFromUnicode)
lUtf8Size = UBound(b) + 1
On Error GoTo 0
'Set buffer for longest possible string i.e. each byte is
'ANSI<=&HFF, thus 1 unicode(2 bytes)for every utf-8 character.
lBufferSize = lUtf8Size * 2
sBuffer = String$(lBufferSize, vbNullChar)
'Translate using code page 65001(UTF-8)
lResult = MultiByteToWideChar(CP_UTF8, 0, b(0), _
lUtf8Size, StrPtr(sBuffer), lBufferSize)
'Trim result to actual length
If lResult Then
UTF8_Decode = Left$(sBuffer, lResult)
'Debug.Print UTF8_Decode
End If
End If
EndFunction:
End Function

'Unicode转换为UTF-8.
Public Function UTF8_Encode(ByVal strUnicode As String) As String 'ByVal strUnicode As Byte
Dim TLen As Long
TLen = Len(strUnicode)
If TLen = 0 Then Exit Function
Dim lBufferSize As Long
Dim lResult As Long
Dim b() As Byte
'Set buffer for longest possible string.
lBufferSize = TLen * 3 + 1
ReDim b(lBufferSize - 1)
'Translate using code page 65001(UTF-8).
lResult = WideCharToMultiByte(CP_UTF8, 0, StrPtr(strUnicode), _
TLen, b(0), lBufferSize, vbNullString, 0)
'Trim result to actual length.
If lResult Then
lResult = lResult - 1
ReDim Preserve b(lResult)
UTF8_Encode = StrConv(b, vbUnicode)
End If
End Function

Answer 2

Private Declare Function WideCharToMultiByte Lib "kernel32" (ByVal CodePage As Long, ByVal dwFlags As Long, ByVal lpWideCharStr As Long, ByVal cchWideChar As Long, ByRef lpMultiByteStr As Any, ByVal cchMultiByte As Long, ByVal lpDefaultChar As String, ByVal lpUsedDefaultChar As Long) As Long
Private Declare Function MultiByteToWideChar Lib "kernel32" (ByVal CodePage As Long, ByVal dwFlags As Long, ByVal lpMultiByteStr As Long, ByVal cchMultiByte As Long, ByVal lpWideCharStr As Long, ByVal cchWideChar As Long) As Long
Private Const CP_UTF8 = 65001

‘utf8转unicode
Function Utf8ToUnicode(ByRef Utf() As Byte) As String
Dim lRet As Long
Dim lLength As Long
Dim lBufferSize As Long
lLength = UBound(Utf) - LBound(Utf) + 1
If lLength <= 0 Then Exit Function
lBufferSize = lLength * 2
Utf8ToUnicode = String$(lBufferSize, Chr(0))
lRet = MultiByteToWideChar(CP_UTF8, 0, VarPtr(Utf(0)), lLength, StrPtr(Utf8ToUnicode), lBufferSize)
If lRet <> 0 Then
Utf8ToUnicode = Left(Utf8ToUnicode, lRet)
End If
End Function

‘unicode转utf8
Function UnicodeToUtf8(ByVal UCS As String) As Byte()
Dim lLength As Long
Dim lBufferSize As Long
Dim lResult As Long
Dim abUTF8() As Byte
lLength = Len(UCS)
If lLength = 0 Then Exit Function
lBufferSize = lLength * 3 + 1
ReDim abUTF8(lBufferSize - 1)
lResult = WideCharToMultiByte(CP_UTF8, 0, StrPtr(UCS), lLength, abUTF8(0), lBufferSize, vbNullString, 0)
If lResult <> 0 Then
lResult = lResult - 1
ReDim Preserve abUTF8(lResult)
UnicodeToUtf8 = abUTF8
End If
End Function

Private Sub Command1_Click()
Dim byt() As Byte
byt = UnicodeToUtf8("测试")
Debug.Print Hex(byt(0)) & Hex(byt(1)) & Hex(byt(2))
Debug.Print Utf8ToUnicode(byt())
End Sub