code: public String encoding()
    {
      if (_readEncoding != null)
        return _readEncoding;
  
      CharSegment value = getHeaderBuffer("Content-Type");
  
      if (value == null)
        return null;
  
      int i = value.indexOf("charset");
      if (i < 0)
        return null;
  
      int len = value.length();
      for (i += 7; i < len && Character.isWhitespace(value.charAt(i)); i++) {
      }
  
      if (i >= len || value.charAt(i) != '=')
        return null;
  
      for (i++; i < len && Character.isWhitespace(value.charAt(i)); i++) {
      }
  
      if (i >= len)
        return null;
  
      char end = value.charAt(i);
      if (end == '"') {
        int tail;
        for (tail = ++i; tail < len; tail++) {
          if (value.charAt(tail) == end)
            break;
        }
  
        _readEncoding = Encoding.getMimeName(value.substring(i, tail));
  
        return _readEncoding;
      }
  
      int tail;
      for (tail = i; tail < len; tail++) {
        if (Character.isWhitespace(value.charAt(tail))
            || value.charAt(tail) == ';')
          break;
      }
  
      _readEncoding = Encoding.getMimeName(value.substring(i, tail));
  
      return _readEncoding;
    }
docs: Returns the character encoding of a post.