.net中错误日志的写入

18 public static void SaveError(Exception ex,HttpContext hc,HttpRequest hr)
19   {
20    string temp ;
21    StreamWriter sw ;
22
23    //如果存在文件
24    if(File.Exists(hr.PhysicalApplicationPath+@"Error.txt"))
25    {
26     sw = File.AppendText(hr.PhysicalApplicationPath+@"Error.txt") ;
27     temp = DateTime.Now.ToString() + "------------------------------------------------------------------------------------ ";
28     temp += "错误消息:" + ex.Message +" ";
29     temp += "导致错误的应用程序或对象的名称:" + ex.Source +" ";
30     temp += "堆栈内容:" + ex.StackTrace +" ";
31     temp += "引发异常的方法:" + ex.TargetSite +" ";
32     temp += "错误页面" +hr.RawUrl + " ";
33
34     sw.WriteLine(temp) ;
35     sw.Close() ;
36    }
37   }