如何使用ASP.NET显示存储在SQL Server数据库中的图片？

Question

I have a SQL Server 2008 database that has image field which contains a picture.

I have a gridview in my ASP.NET web program, and I need to show the picture in:

1. my gridview

2. my image control that I have in the form

Can I get any sample code ?

Thanks in advance.

Answer 1

I believe that the Image will come over as binary. You will need to convert the binary to image.

These references will help you with the conversion

Silverlight 4.0: How to convert byte[] to image?

http://www.eggheadcafe.com/community/aspnet/2/10038022/convert-binary-data-to-an-image.aspx

Answer 2

use Generic handler to fetch image from database and to show that use ifram that will be better option to show files on web.

                iframeFile.Attributes.Add("src", "/ShowImage.ashx?id=" + id);

And this is a Generic handler code to show image files and also for pdf files. if you just want to show image files just remove if else conditions and use image/jpeg for extension.

public class ShowImage : IHttpHandler
{
    public void ProcessRequest(HttpContext context)
    {
        Int32 imgID;
        if (context.Request.QueryString["id"] != null)
            imgID = Convert.ToInt32(context.Request.QueryString["id"]);
        else
            throw new ArgumentException("No parameter specified");

        byte[] buffer = ShowEmpImage(imgID);
        bool temp = false;
        string extension = "";
        var enc = new ASCIIEncoding();
        var header = enc.GetString(buffer);
        dbClass db = new dbClass();
        extension = db.GetID("select fileExtension from tableName WHERE LOGuid=" + imgID, "fileExtension");
        if (extension == null || extension == "")
        {

            if (buffer[0] == 0x25 && buffer[1] == 0x50
            && buffer[2] == 0x44 && buffer[3] == 0x46)
            {
                temp = header.StartsWith("%PDF-");
                extension = "application/pdf";
            }
            else if (buffer[0] == 0xFF && buffer[1] == 0xD8
            && buffer[2] == 0xFF && buffer[3] == 0xE0)
            {
                temp = header.StartsWith("%JPG-");
                extension = "image/jpeg";
                extension = "image/jpg";
            }
            else if (buffer[0] == 0x89 && buffer[1] == 0x50
            && buffer[2] == 0x4E && buffer[3] == 0x47)
            {
                temp = header.StartsWith("%PNG-");
                extension = "image/jpeg";
                extension = "image/png";
            }
            else if (buffer[0] == 0x49 && buffer[1] == 0x49
            && buffer[2] == 0x2A && buffer[3] == 0x00)
            {
                temp = header.StartsWith("%TIF-");
                extension = "image/jpeg";
                extension = "image/tiff";
                extension = "image/tif";
            }
            else if (buffer[0] == 0x47 && buffer[1] == 0x49
            && buffer[2] == 0x46 && buffer[3] == 0x38)
            {
                temp = header.StartsWith("%GIF-");
                extension = "image/jpeg";
                extension = "image/gif";
            }
            else if (buffer[0] == 0x42 && buffer[1] == 0x4D
            && buffer[2] == 0x46 && buffer[3] == 0x38)
            {
                temp = header.StartsWith("%BMP-");
                extension = "image/jpeg";
                extension = "image/bmp";
            }
            else if (buffer[0] == 0x00 && buffer[1] == 0x00
            && buffer[2] == 0x01 && buffer[3] == 0x00)
            {
                temp = header.StartsWith("%ICO-");
                extension = "image/jpeg";
                extension = "image/ico";
            }
            else
                extension = "image/jpeg";
            //else
            //extension = "application/pdf";
        }
        context.Response.ContentType = extension;
        context.Response.AddHeader("content-length", buffer.Length.ToString());
        context.Response.BinaryWrite(buffer);
    }

    public byte[] ShowEmpImage(int imgID)
    {
        dbClass db = new dbClass();
        string sql = "SELECT LOGpdf FROM tableName WHERE LOGuid = @ID";
        SqlCommand cmd = new SqlCommand(sql, db.con);
        cmd.CommandType = CommandType.Text;
        cmd.Parameters.AddWithValue("@ID", imgID);
        object img = null;
        try
        {
            db.Connect();
            img = cmd.ExecuteScalar();
        }
        catch
        {
            return null;
        }
        finally
        {
            db.Disconnect();
        }
        return (byte[])img;
    }

    public bool IsReusable
    {
        get
        {
            return false;
        }
    }
}

Answer 3

You could use the data uri scheme with base64 (assuming it is stored in base64) string ie

<img src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg==" alt="Red dot">

See http://en.wikipedia.org/wiki/Data_URI_scheme

So for example if you were using a databound control you would ie for a repeater do this:

<ItemTemplate>
    <img src='data:image/<%# Eval("FileType") %>;base64,<%# Eval("ImageData") %> width='<%# Eval("ImgWidth")%>' height='<%# Eval("ImgHeight")%>' />
</ItemTemplate>