datapersistentunit.pas

随便说说最近项目中的三层架构吧。讲点实际的东西。我最讨厌空讲道理。网上讲道理的太多了

unit DataPersistentUnit;

interface
  uses Windows, Messages, SysUtils, Classes, DBClient, MConnect, SConnect,
       CardServer_TLB, IDataPersistentUnit;

function DataPersistentObj: IDLLDataPersistent; external 'DLLDataPersistent.dll';

type TRDMDataSet = class(TPersistent)
  //封装之后的持久层方法调用：
  private
    IDLLDataPer: IDLLDataPersistent;
    DCOMConn: TDCOMConnection;
    SocketConn: TSocketConnection;
  published
    function BeginTrans(out pMsg: WideString): Boolean; safecall;
    function CommitTrans(out pMsg: WideString): Boolean; safecall;
    function RollBackTrans(out pMsg: WideString): Boolean; safecall;
    function SelectRDMDS(const SqlStr: WideString; var DataSet: TClientDataSet): Boolean; safecall;
    function InsertRDMDS(const SqlStr: WideString; out pMsg: WideString): Boolean; Stdcall;
    function UpdateRDMDS(const SqlStr: WideString; out pMsg: WideString): Boolean; Stdcall;
    function DeleteRDMDS(const SqlStr: WideString; out pMsg: WideString): Boolean; Stdcall;
    procedure CloseClientDS(var DataSet: TClientDataSet); safecall;
    Procedure CloseRDMDS(var DataSet: TClientDataSet); safecall; 
  public
    constructor Create(pDCOMConn: TDCOMConnection);  overload;
    constructor Create(pSocketConn: TSocketConnection); overload;
end;



implementation

constructor TRDMDataSet.Create(pDCOMConn: TDCOMConnection);
begin
  inherited Create;
  DCOMConn := pDCOMConn;
  if not pDCOMConn.Connected then
    pDCOMConn.Connected := true;

  IDLLDataPer := DataPersistentObj;
  IDLLDataPer.SetIDataPerDisp(IRDMCardServerDisp(IDispatch(pDCOMConn.GetServer)));
end;

constructor TRDMDataSet.Create(pSocketConn: TSocketConnection);
begin
  inherited Create;
  SocketConn := pSocketConn;
  if not pSocketConn.Connected then
    pSocketConn.Connected := true;

  IDLLDataPer := DataPersistentObj;
  IDLLDataPer.SetIDataPerDisp(IRDMCardServerDisp(IDispatch(pSocketConn.GetServer)));
end;

function TRDMDataSet.BeginTrans(out pMsg: WideString): Boolean; safecall;
begin
  Result := IDLLDataPer.BeginTrans(pMsg);
end;

function TRDMDataSet.CommitTrans(out pMsg: WideString): Boolean; safecall;
begin
  Result := IDLLDataPer.CommitTrans(pMsg);
end;

function TRDMDataSet.RollBackTrans(out pMsg: WideString): Boolean; safecall;
begin
  Result := IDLLDataPer.RollBackTrans(pMsg);
end;

function TRDMDataSet.SelectRDMDS(const SqlStr: WideString;
                         var DataSet: TClientDataSet): Boolean; safecall;
var
  sPrvName: WideString;
begin
  Result := False;

  if IDLLDataPer.SelectData(@SqlStr, sPrvName) then
  begin
    DataSet.ProviderName := sPrvName;
    try
      DataSet.Close;
      DataSet.Open;
      Result := true;
    except
      Result := false;
    end;
  end
  else
    begin
      if not DCOMConn.Connected then
        DCOMConn.Open;

      if IDLLDataPer.SelectData(@SqlStr, sPrvName) then
      begin
        DataSet.ProviderName := sPrvName;
        try
          DataSet.Close;
          DataSet.Open;
          Result := true;
        except
          Result := false;
        end;
      end;
    end;
end;

function TRDMDataSet.InsertRDMDS(const SqlStr: WideString; out pMsg: WideString): Boolean; Stdcall;
begin
  Result := IDLLDataPer.InsertDataSet(@SqlStr, pMsg);
end;

function TRDMDataSet.UpdateRDMDS(const SqlStr: WideString; out pMsg: WideString): Boolean; Stdcall;
begin
  Result := IDLLDataPer.UpdateDataSet(@SqlStr, pMsg);
end;

function TRDMDataSet.DeleteRDMDS(const SqlStr: WideString; out pMsg: WideString): Boolean; Stdcall;
begin
  Result := IDLLDataPer.DeleteDataSet(@SqlStr, pMsg);
end;

procedure TRDMDataSet.CloseClientDS(var DataSet: TClientDataSet); safecall;
begin
  CloseRDMDS(DataSet);
  DataSet.Close;
end;

Procedure TRDMDataSet.CloseRDMDS(var DataSet: TClientDataSet); safecall;
var
  lsProviderName: WideString;
begin
  lsProviderName := DataSet.ProviderName;
  IDLLDataPer.CloseDataSet(@lsProviderName);
end;

end.