string msg= Encoding.UTF8.GetString(Encoding.UTF8.GetBytes(strcode)); 

string strcode="我是小明";byte[] buffer=Encoding.UTF8.GetBytes(strcode);string msg= Encoding.UTF8.GetString(buffer,0,buffer.Length);

/// <summary> /// 按字節數截取字符串的方法(比SubString好用) /// </summary> /// <param name="source">要截取的字符串（可空）</param> /// <param name="NumberOfBytes">要截取的字節數</param> /// <param name="encoding">System.Text.Encoding</param> /// <param name="suffix">結果字符串的后綴（超出部分顯示為該后綴）</param> /// <returns></returns> public static string SubStringByBytes(string source, int NumberOfBytes, System.Text.Encoding encoding, string suffix = "...") {  if(string.IsNullOrWhiteSpace(source) || source.Length == 0)  return source;  if(encoding.GetBytes(source).Length <= NumberOfBytes)  return source;  long tempLen = 0;  StringBuilder sb = new StringBuilder();  foreach(var c in source)  {  Char[] _charArr = new Char[] { c };  byte[] _charBytes = encoding.GetBytes(_charArr);  if((tempLen + _charBytes.Length) > NumberOfBytes)  {   if(!string.IsNullOrWhiteSpace(suffix))   sb.Append(suffix);   break;  }  else  {   tempLen += _charBytes.Length;   sb.Append(encoding.GetString(_charBytes));  }  }  return sb.ToString(); } /// <summary> /// 按字節數截取字符串的方法(比SubString好用) /// </summary> /// <param name="source">要截取的字符串（可空）</param> /// <param name="NumberOfBytes">要截取的字節數</param> /// <param name="encoding">UTF-8，Unicode，GB2312...</param> /// <param name="suffix">結果字符串的后綴（超出部分顯示為該后綴）</param> /// <returns></returns> public static string SubStringByBytes(string source, int NumberOfBytes, string encoding = "UTF-8", string suffix = "...") {  return SubStringByBytes(source, NumberOfBytes, Encoding.GetEncoding(encoding), suffix); }