VC/VB 进行图像数据存储数据库心得(2)

中华网科技 http://tech.china.com 2005-06-22 11:55:28

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pRs->Close();
pConnection->Close();
}
catch(_com_error &e)
{
// Notify the user of errors if any.
_bstr_t bstrSource(e.Source());
_bstr_t bstrDescription(e.Description());
CString sError;
sError.Format("Source : %s n Description : %sn",(LPCSTR)bstrSource,(LPCSTR)bstrDescription);
AfxMessageBox(sError);
}


三、VB把文件存入数据库IMAGE字段
Sub savepic(FileName As String, IndexNumber As Long)
Dim DcnNWind As New ADODB.Connection
Dim rs As ADODB.Recordset
Set rs = New ADODB.Recordset
DcnNWind.CursorLocation = adUseClient
DcnNWind.Open "Provider=SQLOLEDB.1;Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=CUSTOM;Data Source=SERVER"
rs.CursorType = adOpenKeyset
rs.LockType = adLockOptimistic
rs.Open "CustomInfo", DcnNWind, , adCmdTable
rs.Move (IndexNumber)
Call FileToBlob(rs.Fields("Image"), FileName, FileLen(FileName))
rs.UpdateBatch adAffectCurrent
End Sub

Private Sub FileToBlob(fld As ADODB.Field, FileName As String, Optional ChunkSize As Long )
Dim fnum As Integer, bytesLeft As Long, bytes As Long
Dim tmp() As Byte
If (fld.Attributes And adFldLong) = 0 Then
Err.Raise 1001, , "Field doesn‘t support the GetChunk method."
End If
fnum = FreeFile
Open FileName For Binary As fnum
bytesLeft = LOF(fnum)
Do While bytesLeft
bytes = bytesLeft
If bytes > ChunkSize Then bytes = ChunkSize
ReDim tmp(1 To bytes) As Byte
Get #1, , tmp
fld.AppendChunk tmp
bytesLeft = bytesLeft - bytes
Loop
Close #fnum
End Sub


四、VB把文件从IMAGE字段中读到文件中
Sub loadpic(IndexNumber As Long)
Dim DcnNWind As New ADODB.Connection
Dim rs As ADODB.Recordset
Set rs = New ADODB.Recordset
DcnNWind.CursorLocation = adUseClient
DcnNWind.Open "Provider=SQLOLEDB.1;Integrated Security=SSI;Persist Security Info=False;Initial Catalog=CUSTOM;Data Source=SERVER"
rs.CursorType = adOpenKeyset
rs.LockType = adLockOptimistic
rs.Open "CustomInfo", DcnNWind, , adCmdTable
rs.Move (IndexNumber)
Call BlobToFile(rs.Fields("Image"), "c:windowstemptmp.bmp", rs.Fields("Image").ActualSize)
End Sub

Private Sub BlobToFile(fld As ADODB.Field, FileName As String, Optional ChunkSize As Long )
Dim fnum As Integer, bytesLeft As Long, bytes As Long
Dim tmp() As Byte
If (fld.Attributes And adFldLong) = 0 Then
Err.Raise 1001, , "Field doesn‘t support the GetChunk method."
End If
If Dir$(FileName) <> "" Then Kill FileName
fnum = FreeFile
Open FileName For Binary As fnum
bytesLeft = fld.ActualSize
Do While bytesLeft
bytes = bytesLeft
If bytes > ChunkSize Then bytes = ChunkSize
tmp = fld.GetChunk(bytes)
Put #fnum, , tmp
bytesLeft = bytesLeft - bytes
Loop
Close #fnum
End Sub

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