Delphi中DataSet和JSON的互转

//1）数据集转换为JSON字符串：
//需USES System.JSON;

 function DataSetToJson(ADataset: TDataSet): string;
 // [{"CityId":"18","CityName":"西安"},{"CityId":"53","CityName":"广州"}]
 var
 LRecord: string;
 LField: TField;
 i: integer;
 begin
 Result := '';
 if (not ADataset.Active) or (ADataset.IsEmpty) then
 Exit;
 Result := '[';
 ADataset.DisableControls;
 ADataset.First;
 while not ADataset.Eof do
 begin
 for i :=  to ADataset.FieldCount -  do
 begin
 LField := ADataset.Fields[i];
 if LRecord = '' then
 LRecord := '{"' + LField.FieldName + '":"' + LField.Text + '"'
 else
 LRecord := LRecord + ',"' + LField.FieldName + '":"' + LField.Text + '"';
 if i = ADataset.FieldCount -  then
 begin
 LRecord := LRecord + '}';
 if Result = '[' then
 Result := Result + LRecord
 else
 Result := Result + ',' + LRecord;
 LRecord := '';
 end;
 end;
 ADataset.Next;
 end;
 ADataset.EnableControls;
 Result := Result + ']';

 end;

//2）JSON字符串转换为数据集：

 procedure JsonToDataSet(AJson: string; ADataset: TDataSet);
 var
 jDataSet: TJSONArray;
 jRecord: TJSONObject;
 i, j: Integer;
 begin
 if (AJson = '') or (ADataset = nil) or (not ADataset.Active) then
 Exit;
 jDataSet := TJSONObject.Create.ParseJSONValue(AJson, True) as TJSONArray;
 while not ADataset.Eof do
 ADataset.Delete;
 for i :=  to jDataSet.Size -  do
 begin
 ADataset.Append;
 jRecord := jDataSet.Get(i) as TJSONObject;
 for j :=  to ADataset.FieldCount -  do
 ADataset.Fields[j].Text := jRecord.GetValue(ADataset.Fields[j].FieldName).ToString;
 ADataset.Post;
 end;
 end;