用VB6读写数据库中的图片

很多兄弟在这里问关于VB6读写数据库中的图片的问题，在此有一例，希有所启发。;;;1，以人名和相关图片为例说明，数据库为Access，有如下字段：Name char,picture OLE object,FileLength Number。当为ms sql时，将picture改为lob即可。;;;2，示例包含control：commom dialog,picture,listbox。源码如下：Option ExplicitPrivate Declare Function GetTempFileName Lib "kernel32" Alias "GetTempFileNameA" (ByVal lpszPath As String, ByVal lpPrefixString As String, ByVal wUnique As Long, ByVal lpTempFileName As String) As LongPrivate Declare Function GetTempPath Lib "kernel32" Alias "GetTempPathA" (ByVal nBufferLength As Long, ByVal lpBuffer As String) As LongPrivate Const MAX_PATH = 260Private m_DBConn As ADODB.ConnectionPrivate Const BLOCK_SIZE = 10000' Return a temporary file name.Private Function TemporaryFileName() As StringDim temp_path As StringDim temp_file As StringDim length As Long;;;;' Get the temporary file path.;;;;temp_path = Space$(MAX_PATH);;;;length = GetTempPath(MAX_PATH, temp_path);;;;temp_path = Left$(temp_path, length);;;;' Get the file name.;;;;temp_file = Space$(MAX_PATH);;;;GetTempFileName temp_path, "per", 0, temp_file;;;;TemporaryFileName = Left$(temp_file, InStr(temp_file, Chr$(0)) - 1)End FunctionPrivate Sub Form_Load()Dim db_file As StringDim rs As ADODB.Recordset;;;;' Get the database file name.;;;;db_file = App.Path;;;;If Right$(db_file, 1) <> "" Then db_file = db_file & "";;;;db_file = db_file & "dbpict.mdb";;;;' Open the database connection.;;;;Set m_DBConn = New ADODB.Connection;;;;m_DBConn.Open _"Provider=Microsoft.Jet.OLEDB.4.0;" & _"Data Source=" & db_file & ";" & _"Persist Security Info=False";;;;' Get the list of people.;;;;Set rs = m_DBConn.Execute("SELECT Name FROM People ORDER BY Name", , adCmdText);;;;Do While Not rs.EOFlstPeople.AddItem rs!Namers.MoveNext;;;;Loop;;;;rs.Close;;;;Set rs = NothingEnd SubPrivate Sub Form_Resize();;;;lstPeople.Height = ScaleHeightEnd Sub' Display the clicked person.Private Sub lstPeople_Click()Dim rs As ADODB.RecordsetDim bytes() As ByteDim file_name As StringDim file_num As IntegerDim file_length As LongDim num_blocks As LongDim left_over As LongDim block_num As LongDim hgt As Single;;;;picPerson.Visible = False;;;;Screen.MousePointer = vbHourglass;;;;DoEvents;;;;' Get the record.;;;;Set rs = m_DBConn.Execute("SELECT * FROM People WHERE Name='" & _lstPeople.Text & "'", , adCmdText);;;;If rs.EOF Then Exit Sub;;;;' Get a temporary file name.;;;;file_name = TemporaryFileName();;;;' Open the file.;;;;file_num = FreeFile;;;;Open file_name For Binary As #file_num;;;;' Copy the data into the file.;;;;file_length = rs!FileLength;;;;num_blocks = file_length / BLOCK_SIZE;;;;left_over = file_length Mod BLOCK_SIZE;;;;For block_num = 1 To num_blocksbytes() = rs!Picture.GetChunk(BLOCK_SIZE)Put #file_num, , bytes();;;;Next block_num;;;;If left_over > 0 Thenbytes() = rs!Picture.GetChunk(left_over)Put #file_num, , bytes();;;;End If;;;;Close #file_num;;;;' Display the picture file.;;;;picPerson.Picture = LoadPicture(file_name);;;;picPerson.Visible = True;;;;Width = picPerson.Left + picPerson.Width + Width - ScaleWidth;;;;hgt = picPerson.Top + picPerson.Height + Height - ScaleHeight;;;;If hgt < 1440 Then hgt = 1440;;;;Height = hgt;;;;Kill file_name;;;;Screen.MousePointer = vbDefaultEnd SubPrivate Sub mnuRecordAdd_Click()Dim rs As ADODB.RecordsetDim person_name As StringDim file_num As StringDim file_length As StringDim bytes() As ByteDim num_blocks As LongDim left_over As LongDim block_num As Long;;;;person_name = InputBox("Name");;;;If Len(person_name) = 0 Then Exit Sub;;;;dlgPicture.Flags = _cdlOFNFileMustExist Or _cdlOFNHideReadOnly Or _cdlOFNExplorer;;;;dlgPicture.CancelError = True;;;;dlgPicture.Filter = "Graphics Files|*.bmp;*.ico;*.jpg;*.gif";;;;On Error Resume Next;;;;dlgPicture.ShowOpen;;;;If Err.Number = cdlCancel ThenExit Sub;;;;ElseIf Err.Number <> 0 ThenMsgBox "Error " & Format$(Err.Number) & _;;;;" selecting file." & vbCrLf & Err.DescriptionExit Sub;;;;End If;;;;' Open the picture file.;;;;file_num = FreeFile;;;;Open dlgPicture.FileName For Binary Access Read As #file_num;;;;file_length = LOF(file_num);;;;If file_length > 0 Thennum_blocks = file_length / BLOCK_SIZEleft_over = file_length Mod BLOCK_SIZESet rs = New ADODB.Recordsetrs.CursorType = adOpenKeysetrs.LockType = adLockOptimisticrs.Open "Select Name, Picture, FileLength FROM People", m_DBConnrs.AddNewrs!Name = person_namers!FileLength = file_lengthReDim bytes(BLOCK_SIZE)For block_num = 1 To num_blocks;;;;Get #file_num, , bytes();;;;rs!Picture.AppendChunk bytes()Next block_numIf left_over > 0 Then;;;;ReDim bytes(left_over);;;;Get #file_num, , bytes();;;;rs!Picture.AppendChunk bytes()End Ifrs.UpdateClose #file_numlstPeople.AddItem person_namelstPeople.Text = person_name;;;;End IfEnd Sub