.net中的编码问题

 public static string UrlEncode(string str)
         {
             StringBuilder sb = new StringBuilder();
             byte[] byStr = System.Text.Encoding.UTF8.GetBytes(str); //默认是System.Text.Encoding.Default.GetBytes(str)
             for (int i = 0; i < byStr.Length; i++)
             {
                 sb.Append(@"%" + Convert.ToString(byStr[i], 16));
             }
            
             return (sb.ToString());
         }
 
 C#版web实现UrlEncode（这个方法只可以用于web）
 
private static string charTrans(string zh_cn)
         {
             return System.Web.HttpUtility.UrlEncode(zh_cn, Encoding.UTF8);
         }