我如何显示图像到ImageButton asp.net C＃

Question

这通过将图像文件插入到头像列来更新数据库。 上载到数据库有效，但不会显示在图像按钮中。

protected void imgProfile_Click(object sender, ImageClickEventArgs e)
{
    SqlConnection connection = null;
    try
    {
        FileUpload img = (FileUpload)ofd;
        Byte[] imgByte = null;
        if (img.HasFile && img.PostedFile != null)
        {
            //To create a PostedFile
            HttpPostedFile File = ofd.PostedFile;
            //Create byte Array with file len
            imgByte = new Byte[File.ContentLength];
            //force the control to load data in array
            File.InputStream.Read(imgByte, 0, File.ContentLength);
        }
        // Insert the employee name and image into db
        string conn = ConfigurationManager.ConnectionStrings["SE255_AFloresConnectionString2"].ConnectionString;
        connection = new SqlConnection(conn);

        connection.Open();
        string sql = "UPDATE Users SET Avatar = ('" + imgByte + "') OUTPUT INSERTED.User_ID WHERE Username = ('" + Session["UserName"].ToString() + "')";
        SqlCommand cmd = new SqlCommand(sql, connection);

        int id = Convert.ToInt32(cmd.ExecuteScalar());
        userid.Text = "<script>alert('" + String.Format("Employee ID is" +" "+ id) + "')</script>";
        userid.Visible = false;

        //display
        imgProfile.ImageUrl = "~/Handler1.ashx?id=" + id;
    }
    catch
    {
        //lblResult.Text = "There was an error";
    }
    finally
    {
        connection.Close();
    }

这部分是我卡住的地方，不会在图像按钮上显示它，请帮忙

public void ProcessRequest(HttpContext context)
{
    Int32 empno;
    if (context.Request.QueryString["User_ID"] != null)
        empno = Convert.ToInt32(context.Request.QueryString["User_ID"]);
    else
        throw new ArgumentException("No parameter specified");

    context.Response.ContentType = "image/jpeg";
    Stream strm = ShowEmpImage(empno);
    byte[] buffer = new byte[4096];
    int byteSeq = strm.Read(buffer, 0, 4096);

    while (byteSeq > 0)
    {
        context.Response.OutputStream.Write(buffer, 0, byteSeq);
        byteSeq = strm.Read(buffer, 0, 4096);
    }       
}
public Stream ShowEmpImage(int empno)
{

    string conn = ConfigurationManager.ConnectionStrings["SE255_AFloresConnctionString2"].ConnectionString;
    SqlConnection connection = new SqlConnection(conn);
    string sql = "SELECT Avatar FROM Users WHERE User_ID = @ID";
    SqlCommand cmd = new SqlCommand(sql, connection);
    cmd.CommandType = CommandType.Text;
    cmd.Parameters.AddWithValue("@ID", empno);
    connection.Open();
    object img = cmd.ExecuteScalar();
    try
    {
        return new MemoryStream((byte[])img);
    }
    catch
    {
        return null;
    }
    finally
    {
        connection.Close();
    }
}

这是.aspx文件

    <script type="text/javascript" >
    function clk() {
        var ofd = document.getElementById('<%=ofd.ClientID%>');
        ofd.click();
    }

<asp:Label ID="lblUser" runat="server"></asp:Label>
<asp:Label ID="userid" runat="server"></asp:Label>


<div style="width:100%;">
    <asp:ImageButton ID="imgProfile" CssClass="img-circle img img-rounded" runat="server" Height="100px" Width="100px" OnClientClick="clk();" OnClick="imgProfile_Click"></asp:ImageButton>
    <div style="display:none">
    <asp:FileUpload ID="ofd" runat="server" />
</div>
</div>

Answer 1

string base64String = Convert.ToBase64String(bytes, 0, bytes.Length);
imgProfile.ImageUrl = "data:image/png;base64," + base64String;

在一种从数据库中获取图像字节的方法中，尝试上述几行。 为此，您甚至不需要ashx处理程序。 希望它会帮助你。

Answer 2

为了使其更好，请在您的类中添加此方法并在将其保存到数据库后调用该方法从数据库中获取字节。

public string GetImageAsByte64String(int empno)
{

string conn = ConfigurationManager.ConnectionStrings["SE255_AFloresConnctionString2"].ConnectionString;
SqlConnection connection = new SqlConnection(conn);
string sql = "SELECT Avatar FROM Users WHERE User_ID = @ID";
SqlCommand cmd = new SqlCommand(sql, connection);
cmd.CommandType = CommandType.Text;
cmd.Parameters.AddWithValue("@ID", empno);
connection.Open();
object img = cmd.ExecuteScalar();
try
{
    byte[] imgByte = (byte[])img;
    string base64String = Convert.ToBase64String(imgByte , 0, imgByte.Length);
    return  ("data:image/png;base64," + base64String);

}
catch
{
    return null;
}
finally
{
    connection.Close();
}
}

稍后按如下所示调用此方法以分配给imageButton的ImageUrl属性。

//display
imgProfile.ImageUrl = GetImageAsByte64String(id);