ASP.NETログパス

//1.
protected void Button_StreamWrite_Click(object sender, EventArgs e)
{
    StreamWriter sw = new StreamWriter(@"\xxx.log",true);
    sw.WriteLine("Start");
    sw.WriteLine("   ing...");
    sw.WriteLine("End");
    sw.Close();
}
      C  ,true =      ，     ,  ,  New  ,     

//2.    web    Path
protected void Button_StreamWrite_Click(object sender, EventArgs e)
{
    string appPath = HttpContext.Current.Server.MapPath(@"\log.txt");
    StreamWriter sw = new StreamWriter(appPath,true);
    sw.WriteLine("Start");
    sw.WriteLine("   ing...");
    sw.WriteLine("End");
    sw.Close();
}
      app   Path ,true =      ，     ,  ,  New  ,