将图像存储到数据库 blob；从数据库检索到图片框

Question

嗨，我早些时候发布了这个并得到了一些帮助，但仍然没有可行的解决方案。感谢上次问答，我确定我的“保存到数据库”代码和“检索图片”代码有问题。即使我手动将图片保存在数据库中，它也不会检索。这是我从网络上的 3 或 4 个示例拼凑而成的代码。理想情况下，如果有人有一些已知的好代码并且可以指导我使用它，那将是最好的。

    Dim filename As String = txtName.Text + ".jpg"
    Dim FileSize As UInt32
    Dim ImageStream As System.IO.MemoryStream

    ImageStream = New System.IO.MemoryStream
    PbPicture.Image.Save(ImageStream, System.Drawing.Imaging.ImageFormat.Jpeg)
    ReDim rawdata(CInt(ImageStream.Length - 1))
    ImageStream.Position = 0
    ImageStream.Read(rawdata, 0, CInt(ImageStream.Length))
    FileSize = ImageStream.Length

    Dim query As String = ("insert into actors (actor_pic, filename, filesize) VALUES    (?File, ?FileName, ?FileSize)")
    cmd = New MySqlCommand(query, conn)
    cmd.Parameters.AddWithValue("?FileName", filename)
    cmd.Parameters.AddWithValue("?FileSize", FileSize)
    cmd.Parameters.AddWithValue("?File", rawData)

    cmd.ExecuteNonQuery()

    MessageBox.Show("File Inserted into database successfully!", _
    "Success!", MessageBoxButtons.OK, MessageBoxIcon.Asterisk)

![在此处输入图像描述][1]

'***** 使用以下代码重新绑定到图片框：

    Dim filename As String = txtName.Text + ".jpg"
    Dim FileSize As UInt32
    Dim ImageStream As System.IO.MemoryStream

    ImageStream = New System.IO.MemoryStream
    PbPicture.Image.Save(ImageStream, System.Drawing.Imaging.ImageFormat.Jpeg)
    ReDim rawdata(CInt(ImageStream.Length - 1))
    ImageStream.Position = 0
    ImageStream.Read(rawdata, 0, CInt(ImageStream.Length))
    FileSize = ImageStream.Length

    Dim query As String = ("insert into actors (actor_pic, filename, filesize) VALUES    (?File, ?FileName, ?FileSize)")
    cmd = New MySqlCommand(query, conn)
    cmd.Parameters.AddWithValue("?FileName", filename)
    cmd.Parameters.AddWithValue("?FileSize", FileSize)
    cmd.Parameters.AddWithValue("?File", rawData)

    cmd.ExecuteNonQuery()

    MessageBox.Show("File Inserted into database successfully!", _
    "Success!", MessageBoxButtons.OK, MessageBoxIcon.Asterisk)

Answer 1

好吧，由于没有得到任何帮助，我猛烈抨击了这个问题，并最终让它发挥了作用。这是我的工作代码。

从图片框保存到 MySQL (pbPicture)

    Dim filename As String = txtName.Text + ".jpg"
    Dim FileSize As UInt32

    conn.Close()

    Dim mstream As New System.IO.MemoryStream()
    PbPicture.Image.Save(mstream, System.Drawing.Imaging.ImageFormat.Jpeg)
    Dim arrImage() As Byte = mstream.GetBuffer()

    FileSize = mstream.Length
    Dim sqlcmd As New MySqlCommand
    Dim sql As String
    mstream.Close()

    sql = "insert into [your table]  (picture, filename, filesize) 
                               VALUES(@File, @FileName, @FileSize)"

    Try
        conn.Open()
        With sqlcmd
            .CommandText = sql
            .Connection = conn
            .Parameters.AddWithValue("@FileName", filename)
            .Parameters.AddWithValue("@FileSize", FileSize)
            .Parameters.AddWithValue("@File", arrImage)

            .ExecuteNonQuery()
        End With
    Catch ex As Exception
        MsgBox(ex.Message)
    Finally
        conn.Close()
    End Try

从 MySQL db 加载返回图片框

   Dim adapter As New MySqlDataAdapter
    adapter.SelectCommand = Cmd

    data = New DataTable

    adapter = New MySqlDataAdapter("select picture from [yourtable]", conn)

笔记！！只能在图片框中放一张图片，所以显然这个查询只能为你返回一条记录

    commandbuild = New MySqlCommandBuilder(adapter)
    adapter.Fill(data)

    Dim lb() As Byte = data.Rows(0).Item("picture")
    Dim lstr As New System.IO.MemoryStream(lb)
    PbPicture.Image = Image.FromStream(lstr)
    PbPicture.SizeMode = PictureBoxSizeMode.StretchImage
    lstr.Close()