public string UtoGB(string str) 
            { 
                string[] ss = str.Split('%'); 
                byte[] bs = new Byte[ss.Length - 1]; 
                for (int i = 1; i < ss.Length; i++) 
                { 
                    bs[i - 1] = Convert.ToByte(Convert2Hex(ss[i]));   //ss[0]为空串  
                }

      1:
                char[] chrs = System.Text.Encoding.GetEncoding("GB2312").GetChars(bs); 
                string s = ""; 
                for (int i = 0; i < chrs.Length; i++) 
                { 
                    s += chrs[i].ToString(); 
                }

                  return s; 

      2:

                  return  System.Text.Encoding.GetEncoding("GB2312").GetString(bs); 
                } 
        private string Convert2Hex(string pstr) //转换为16进制
        { 
            if (pstr.Length == 2) 
            { 
                pstr = pstr.ToUpper(); 
                string hexstr = "0123456789ABCDEF"; 
                int cint = hexstr.IndexOf(pstr.Substring(0, 1)) * 16 + hexstr.IndexOf(pstr.Substring(1, 1)); 
                return cint.ToString(); 
            } 
            else 
            { 
                return ""; 
            } 
        }  

本文转自94cool博客园博客，原文链接：http://www.cnblogs.com/94cool/articles/1499271.html，如需转载请自行联系原作者