SQL将图像下载到图片框'；内存不足'；错误

*strong text*好的，我有一个测试应用程序，它只是测试向SQL Server上传和下载图像的过程。上载代码可以工作，但当我尝试从SQL Server检索图像时，收到一个“内存不足”错误。但是，当我将picturebox从

.BackGroundImage

更改为仅

.Image

时，代码工作正常

我需要的图像是在一个BackGoundImage格式，以便我可以很容易地改变图像的大小（中心，拉伸等）

错误：

发生“System.OutOfMemoryException”类型的未处理异常 在System.Drawing.dll中

其他信息：内存不足

从SQL Server检索映像的代码为：

Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
'Retrieve Image
        GroupBox2.BringToFront()
        GroupBox2.Visible = True
        Label1.Visible = False
        TextBox1.Visible = False
        con.Open()
        Dim cmd As New SqlCommand("SELECT DP FROM PersonsA WHERE Members_ID = 1", con)
        cmd.CommandType = CommandType.Text
        Dim ImgStream As New IO.MemoryStream(CType(cmd.ExecuteScalar, Byte()))
        PictureBox2.BackgroundImage = Image.FromStream(ImgStream, False, True)

        ImgStream.Dispose()
        con.Close()
    End Sub

错误突出显示了

PictureBox2.BackgroundImage=Image.FromStream（ImgStream，False，True）

行

其他信息：

• 由于

  Members\u ID

  是主键，因此只需要1行
• SQL Server是MS SQL Server+Management Studio

• DP

  列的格式为“Image”，并按如下方式存储图片：

0xFFD8FF000104A46494600010201000000000000000FF

这是上传图像代码（正常）

导入和Dims

Imports System.Data.SqlClient
Imports System.IO
Public Class Form1
    'path variable use for Get application running path
    Dim path As String = (Microsoft.VisualBasic.Left(Application.StartupPath, Len(Application.StartupPath) - 9))
    Dim con As New SqlConnection("CONNECTION_STRING;")
    Dim cn As New SqlConnection("CONNECTION_STRING;")
    Dim cmd As SqlCommand

你知道我为什么会收到“内存不足错误”吗？这个程序很小，不需要使用过多的RAM，所以它必须和我的代码在一起

[编辑1]

以下Jaques非常有用的建议我将代码改为以下内容-注意有两个错误，因为read没有声明-应该声明为什么

 Dim cmd As New SqlCommand("SELECT DP FROM PersonsA WHERE Members_ID = 1", con)
        cmd.CommandType = CommandType.Text

        Dim Buffersize As Integer = 4096
        Dim retval As Long = 0
        Dim TempLen1 As Long = 0
        Dim startindex As Long = 0
        Dim reference_temp As [Byte]() = New [Byte](4095) {}
        Dim RefTemp As New List(Of Byte)()
        Dim Read As 
        retval = read.GetBytes(0, startindex, reference_temp, 0, buffersize)
        '0 is the first Column
        TempLen1 += retval
        While retval = buffersize
            RefTemp.AddRange(reference_temp)
            startindex += buffersize
            retval = read.GetBytes(0, startindex, reference_temp, 0, buffersize)
            TempLen1 += retval
        End While
        RefTemp.AddRange(reference_temp)
        Dim Reference_temp1 As Byte() = RefTemp.GetRange(0, CInt(TempLen1)).ToArray()
    End Sub

[编辑2]

我现在在

retval-read.GetBytes（16，startindex

…行上收到一个错误

“System.InvalidOperationException”类型的未处理异常 发生在Microsoft.VisualBasic.dll中

其他信息：没有数据时读取的尝试无效 现在

到目前为止，我的代码是：

  'Retrieve Image
        GroupBox2.BringToFront()
        GroupBox2.Visible = True
        Label1.Visible = False
        TextBox1.Visible = False
        con.Open()
        Dim cmd As New SqlCommand("SELECT DP FROM PersonsA WHERE Members_ID = 1", con)
        cmd.CommandType = CommandType.Text
        Dim read = cmd.ExecuteReader

        Dim Buffersize As Integer = 4096
        Dim retval As Long = 0
        Dim TempLen1 As Long = 0
        Dim startindex As Long = 0
        Dim reference_temp As [Byte]() = New [Byte](4095) {}
        Dim RefTemp As New List(Of Byte)()

        retval = read.GetBytes(16, startindex, reference_temp, 16, Buffersize)
        '0 is the first Column
        TempLen1 += retval
        While retval = buffersize
            RefTemp.AddRange(reference_temp)
            startindex += buffersize
            retval = read.GetBytes(16, startindex, reference_temp, 16, Buffersize)
            TempLen1 += retval
        End While
        RefTemp.AddRange(reference_temp)
        Dim Reference_temp1 As Byte() = RefTemp.GetRange(16, CInt(TempLen1)).ToArray()

        Dim ImgStream As New IO.MemoryStream(Reference_temp1)
        PictureBox2.BackgroundImage = Image.FromStream(ImgStream, False, True)
        ImgStream.Dispose()

---

为什么不使用数据读取器中的GetBytes，比如（它的C#，但我相信您可以转换为：）

将其转换为VB：

int buffersize = 4096;
long retval = 0;
long TempLen1 = 0;
long startindex = 0;
Byte[] reference_temp = new Byte[4096];
List<byte> RefTemp = new List<byte>();
retval = read.GetBytes(0, startindex, reference_temp, 0, buffersize);   //0 is the first Column
TempLen1 += retval;
while (retval == buffersize)
{
    RefTemp.AddRange(reference_temp);
    startindex += buffersize;
    retval = read.GetBytes(0, startindex, reference_temp, 0, buffersize);
    TempLen1 += retval;
}
RefTemp.AddRange(reference_temp);
byte[] Reference_temp1 = RefTemp.GetRange(0, (int)TempLen1).ToArray();

---

我要感谢Jaques为帮助我所做的努力。解决方案比这个答案简单一点——这仍然会导致“内存不足”错误。但是，我们非常赞赏所作的努力。最后，这段代码没有任何错误

'检索图像 GroupBox2.BringToFront（） GroupBox2.Visible=True Label1.Visible=False TextBox1.Visible=False 将流变暗为新内存流（）

---

是的，但我如何将其放入代码中，以便它使用SQL映像并将其输出到图片框？我已将我的代码“添加”到您的代码中。将C#部分按原样转换为VB，它应该可以工作。嗨，我真的很感谢你的帮助。我将您的代码转换为vb.net，在read.GetBtyes行中留下了两个错误。它说的是>“读取未声明”。请注意，我在代码的末尾添加了一行

Dim Read=cmd.ExecuteDataReader（）您需要添加它。在声明之后添加一个
if（read.HasRows）
可能是明智的，这样当没有行时，就不会出现异常。我编辑了答案是的，我自己想出来的。你能看一下我的第二次编辑吗？我添加了一个新错误的最新代码我可能没有正确地构造它。如果您得到一个
OutOfMemoryException
，通常是因为您的进程是32位的，并且已经分配了所有可寻址的2GB内存，或者它已经用完了所有的系统句柄或GDI句柄。无论哪种方式，您都可以通过观察任务管理器来判断。由于错误发生在System.Drawing.dll中，我强烈怀疑您的GDI句柄不足。每个进程限制为10000个GDI对象。理想情况下，您的流程应该不会接近该限制。
'Retrieve Image
        GroupBox2.BringToFront()
        GroupBox2.Visible = True
        Label1.Visible = False
        TextBox1.Visible = False
        con.Open()
        Dim cmd As New SqlCommand("SELECT DP FROM PersonsA WHERE Members_ID = 1", con)
        cmd.CommandType = CommandType.Text
        Dim read = cmd.ExecuteReader();
        if(read.HadRows) then       
             read.Read()   'Reads the first record from the DataReader

int buffersize = 4096;
long retval = 0;
long TempLen1 = 0;
long startindex = 0;
Byte[] reference_temp = new Byte[4096];
List<byte> RefTemp = new List<byte>();
retval = read.GetBytes(0, startindex, reference_temp, 0, buffersize);   //0 is the first Column
TempLen1 += retval;
while (retval == buffersize)
{
    RefTemp.AddRange(reference_temp);
    startindex += buffersize;
    retval = read.GetBytes(0, startindex, reference_temp, 0, buffersize);
    TempLen1 += retval;
}
RefTemp.AddRange(reference_temp);
byte[] Reference_temp1 = RefTemp.GetRange(0, (int)TempLen1).ToArray();

Dim ImgStream As New IO.MemoryStream(Reference_temp1)
PictureBox2.BackgroundImage = Image.FromStream(ImgStream, False, True)
ImgStream.Dispose()
EndIf

    con.Open()

    Dim cmd As New SqlCommand("SELECT DP FROM PersonsA WHERE Members_ID = 1", con)
    cmd.CommandType = CommandType.Text

    Dim image As Byte() = DirectCast(cmd.ExecuteScalar(), Byte())
    Stream.Write(image, 0, image.Length)

    con.Close()

    Dim bitmap As New Bitmap(stream)
    PictureBox2.BackgroundImage = bitmap
    PictureBox2.BackgroundImageLayout = ImageLayout.Stretch