PREGUNTAS CONTESTADAS - Visual Basic.NET

Usando una PictureBox



Private sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load

       Dim ms As New MemoryStream(ExtraerImagen("Select foto from usuario"))

        Me.PictureBox1.Image = Image.FromStream(ms)

        Me.PictureBox1.SizeMode = PictureBoxSizeMode.StretchImage

End Sub



    Function ExtraerImagen(ByVal consulta As String) As Byte()

        Dim SqlSelect As String = consulta

        Dim Command As New SqlCommand(SqlSelect, con)

        Dim MyPhoto() As Byte = CType(Command.ExecuteScalar(), Byte())

        Return MyPhoto

    End Function



Y con un archivo pues sólo lo tienes que extraer y luego leer, para extraer usa este código:

private sub BtnExtraer_Click(sender As System.Object, e As System.EventArgs) Handles BtnExtraer.Click

            Try

                con.Open()

                Dim ex As String

                cmd.CommandText = "SELECT extension FROM archivoss WHERE id = " & Val(Me.TextBox2.Text)

                cmd.Connection = con

                Dim dr1 As SqlDataReader = cmd.ExecuteReader(CommandBehavior.CloseConnection)

                dr1.Read()

                ex = dr1.GetString(0)

                dr1.Close()

                con.Close()

                If SaveFileDialog1.ShowDialog = Windows.Forms.DialogResult.OK Then

                    con.Open()

                    Dim dire As String = Me.SaveFileDialog1.FileName & "." & ex

                    cmd.CommandText = "SELECT archivo FROM archivoss WHERE id = " & Val(Me.TextBox2.Text)

                    cmd.Connection = con

                    Dim dr As SqlDataReader = cmd.ExecuteReader(CommandBehavior.CloseConnection)

                    dr.Read()

                    Dim bufferSize As Int32 = Convert.ToInt32(dr.GetBytes(0, 0, Nothing, 0, 0))

                    Dim aByte(bufferSize - 1) As Byte

                    dr.GetBytes(0, 0, aByte, 0, bufferSize)

                    dr.Close()

                    WriteBinaryFile(aByte, dire)

                    MsgBox("Exportado", MsgBoxStyle.Information, "Echo")

                    Me.Close()

                End If

                Catch ex As Exception

                MessageBox.Show(ex.Message)

                con.Close()

            End Try

            con.Close()

End sub



Private Sub WriteBinaryFile(ByVal aByte() As Byte, ByVal fileName As String)

        If (aByte Is Nothing) Then _

            Throw New ArgumentNullException("aByte", "No se ha especificado ningún array de Bytes.")

        If (String.IsNullOrEmpty(fileName)) Then _

            Throw New ArgumentNullException("fileName", "No se ha especificado el archivo de destino.")

        Try

            If (File.Exists(fileName)) Then

                If (MessageBox.Show("Ya existe un archivo con el mismo nombre. " & "¿Desea sobrescribirlo?", "Grabar archivo", _

                    MessageBoxButtons.YesNo, _

                    MessageBoxIcon.Question) = _

                    Windows.Forms.DialogResult.No) Then Return

                File.Delete(fileName)

            End If

            Dim data As Long = aByte.Length

            Dim tempFileName As String = Path.GetTempFileName()

            Using fs As New FileStream(tempFileName, FileMode.OpenOrCreate)

                Dim bw As New BinaryWriter(fs)

                bw.Write(aByte, 0, Convert.ToInt32(data))

                bw.Flush()

                bw = Nothing

            End Using

            File.Move(tempFileName, fileName)

        Catch ex As Exception

            Throw

        End Try

    End Sub

    Private Sub TextBox2_KeyPress(sender As System.Object, e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox2.KeyPress

        Dim Sep = Application.CurrentCulture.NumberFormat.NumberDecimalSeparator

        If Not (Char.IsNumber(e.KeyChar) Or e.KeyChar.Equals(Sep) Or Char.IsControl(e.KeyChar)) Then e.Handled = True

    End Sub

    Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click

        Me.Close()

    End Sub