function T_SunnySky_SDK.JoinItems(AParamDic: TDictionary<string, string>): string;
var
  sb : TStringBuilder;
  key :  TPair<string,string>;
begin
   if not Assigned(AParamDic)  then
      Result := ''
   else if AParamDic.Count = 0  then
      Result := ''
   else begin
         sb := TStringBuilder.Create;
         try
             for key in AParamDic do
             begin
                 if sb.Length > 0  then
                   sb.Append('&');

                 sb.Append(key.Key);
                 sb.Append('=');
                 sb.Append(HTTPEncode(key.Value));
             end;

             Result := sb.ToString;
         finally
            sb.Free;
         end;
   end;
end;

　　

　Delphi 的 TStringBuilder 可以完美实现Jave ,C#的TStringBuilder功能．  :)