write to file asp.net c#

public void writeToFile(string msg)

{

string fileName = "tes.txt";

string appPath = HttpContext.Current.Request.ApplicationPath;

string physicalPath = HttpContext.Current.Request.MapPath(appPath);

fileName = Path.Combine(physicalPath, fileName);

StreamWriter writer = new StreamWriter(fileName);

writer.WriteLine(msg);

writer.Flush();

writer.Close();

}