image upload /download

Question

hi..
pls help me to solve  error
 
mainpage aspx.cs
------------------------------
using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void btnSubmit_Click(object sender, EventArgs e)
{
SqlConnection connection = null;
try
{
FileUpload img = (FileUpload)imgUpload;
Byte[] imgByte = null;
if (img.HasFile && img.PostedFile != null)
{
//To create a PostedFile
HttpPostedFile File = imgUpload.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["Connection"].ConnectionString;
connection = new SqlConnection(conn);
connection.Open();
string sql = "INSERT INTO EmpDetails1(empname,empimg) VALUES(@enm, @eimg) SELECT @@IDENTITY";
SqlCommand cmd = new SqlCommand(sql, connection);
cmd.CommandType = CommandType.Text;
cmd.Parameters.AddWithValue("@enm", txtEName.Text.Trim());
cmd.Parameters.AddWithValue("@eimg", imgByte);
int id = Convert.ToInt32(cmd.ExecuteScalar());
lblResult.Text = String.Format("Employee ID is {0}", id);
}
catch
{
lblResult.Text = "There was an error";
}
finally
{
connection.Close();
}
}
protected void btnGet_Click(object sender, EventArgs e)
{
int id = 0;
id = Convert.ToInt32(txtEmpid.Text);
Image1.ImageUrl = "~/ShowImage.ashx?id=" + id;
}
}
 
handler.ashx
---------------
using System;
using System.Configuration;
using System.Web;
using System.IO;
using System.Data;
using System.Data.SqlClient;
 
public class ShowImage : IHttpHandler {
public void ProcessRequest(HttpContext context)
{
Int32 empno;
if (context.Request.QueryString["id"] != null)
empno = Convert.ToInt32(context.Request.QueryString["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["Connection"].ConnectionString;
SqlConnection connection = new SqlConnection(conn);
string sql = "SELECT empimg FROM empdetails1 WHERE empid = @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();
}
}
public bool IsReusable
{
get
{
return false;
}
}

}

--------------------------
error
object reference  not set to be instance of an object