C# 如何使用ASP.NET显示存储在SQL Server数据库中的图片？

我有一个SQLServer2008数据库，它有一个包含图片的图像字段

我的ASP.NET web程序中有一个gridview，我需要在以下位置显示图片：

我的网格视图

我在窗体中的图像控件

我能得到一些示例代码吗

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提前谢谢。

我相信图像会以二进制形式出现。您需要将二进制文件转换为图像

这些参考资料将帮助您进行转换

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我相信图像将以二进制形式出现。您需要将二进制文件转换为图像

这些参考资料将帮助您进行转换

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您可以将数据uri方案与base64（假设它存储在base64中）字符串一起使用，即

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

看

因此，例如，如果您使用的是数据绑定控件，您将（例如，对于中继器）执行以下操作：

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

;base64，宽度=''高度=''/>

您可以将数据uri方案与base64（假设它存储在base64中）字符串一起使用，即

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

看

因此，例如，如果您使用的是数据绑定控件，您将（例如，对于中继器）执行以下操作：

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

;base64，宽度=''高度=''/>

使用通用处理程序从数据库中获取图像，并显示使用ifram将是在web上显示文件的更好选项

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

这是一个显示图像文件和pdf文件的通用处理程序代码。如果您只想显示图像文件，只需删除if-else条件并使用image/jpeg作为扩展名

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;
        }
    }
}

---

使用通用处理程序从数据库中获取图像，并显示使用ifram将是在web上显示文件的更好选项

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

这是一个显示图像文件和pdf文件的通用处理程序代码。如果您只想显示图像文件，只需删除if-else条件并使用image/jpeg作为扩展名

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;
        }
    }
}

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可能重复的是存储在Filestream中的图像还是存储在VARBINIAL列中的图像？可能重复的是存储在Filestream中的图像还是存储在VARBINIAL列中的图像；跨浏览器不完全支持数据uri，因此可能不适合您；跨浏览器不完全支持数据uri，因此可能不适合您。