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.IO; //Directory, Path, FileInfo
using System.Text; //StringBuilder

public partial class _Default : System.Web.UI.Page 
{
    private const string TARGET_DIR = "~/";

    protected void btnSubmit_Click(object sender, EventArgs e)
    {
        //Check target directory
        string sTargetDir = Request.MapPath(TARGET_DIR);
        System.Diagnostics.Debug.Assert(Directory.Exists(sTargetDir));

        StringBuilder objDisplay = new StringBuilder();
        objDisplay.Append("<h3>You have just saved:</h3><ul>");
        
        //Iterate through posted files (foreach does not work with empty file inputs)
        for (int i = 0; i < Request.Files.Count; i++)
        {
            HttpPostedFile objFile = Request.Files[i];
            //Make sure file input has content
            if ((objFile.ContentLength > 0) && (objFile.FileName.Length > 0))
            {
                //Get target file path for save as
                string sFileName = Path.GetFileName(objFile.FileName);
                string sFilePath = Path.Combine(sTargetDir, sFileName);
                FileInfo objFileInfo = new FileInfo(sFilePath);
                //No business rule, i.e. we just want to avoid failure
                if (objFileInfo.Exists)
                {
                    objFileInfo.Attributes &= ~FileAttributes.ReadOnly;
                    objFileInfo.Delete();
                }
                //Save file
                objFile.SaveAs(sFilePath);
                //Append link
                objDisplay.AppendFormat("<li><a href=\"{0}\">{1}</a></li>",
                    this.ResolveUrl(Path.Combine(TARGET_DIR, sFileName)),
                    sFileName);
            }
        }

        objDisplay.Append("</ul>");
        litDisplay.Text = objDisplay.ToString();
    }
}