Question

所以，我有一个使用WM_COPYDATA的类允许应用程序进行通信。

__next__

发送申请：

type
  TMyRec = record
    Name: string[255];
    Age: integer;
    Birthday: TDateTime;
  end;

function TAppCommunication.SendRecord(const ARecordToSend: Pointer; const ARecordType: PTypeInfo): Boolean;
var
  _Stream: TMemoryStream;
begin
  _Stream := TMemoryStream.Create;
  try
    _Stream.Write(NativeInt(ARecordType), SizeOf(TTypeInfo));
    _Stream.Write(NativeInt(ARecordToSend), SizeOf(ARecordToSend));
    _Stream.Position := 0;

    Result := SendStreamData(_Stream, TCopyDataType.cdtRecord)
  finally
    FreeAndNil(_Stream);
  end;
end;

function TAppCommunication.SendStreamData(const AStream: TMemoryStream;
  const ADataType: TCopyDataType): Boolean;
var
  _CopyDataStruct: TCopyDataStruct;
begin
  Result := False;

  if AStream.Size = 0 then
    Exit;

  _CopyDataStruct.dwData := integer(ADataType);
  _CopyDataStruct.cbData := AStream.Size;
  _CopyDataStruct.lpData := AStream.Memory;

  Result := SendData(_CopyDataStruct);
end;

function TAppCommunication.SendData(const ADataToSend: TCopyDataStruct)
  : Boolean;
var
  _SendResponse: integer;
  _ReceiverHandle: THandle;
begin
  Result := False;

  _ReceiverHandle := GetRemoteReceiverHandle;
  if (_ReceiverHandle = 0) then
    Exit;

  _SendResponse := SendMessage(_ReceiverHandle, WM_COPYDATA,
    integer(FLocalReceiverForm.Handle), integer(@ADataToSend));

  Result := _SendResponse <> 0;
end;

接收申请：

procedure TSenderMainForm.BitBtn1Click(Sender: TObject);
var
  _AppCommunication: TAppCommunication;
  _ms: TMemoryStream;
  _Rec: TMyRec;
  _Record: TAttrData;
begin
  _AppCommunication := TAppCommunication.Create('LocalReceiverName', OnAppMessageReceived);
  _ms := TMemoryStream.Create;
  try
    _AppCommunication.SetRemoteReceiverName('LocalReceiverNameServer');
    _AppCommunication.SendString('ąčęėįšųūž123');
    _AppCommunication.SendInteger(998);
    _AppCommunication.SendDouble(0.95);

    _Rec.Name := 'Edijs';
    _Rec.Age := 29;
    _Rec.Birthday := EncodeDate(1988, 10, 06);
    _Record.Len := 1988;
    //_ms.Write(_Rec, SizeOf(TMyRec));
    //_AppCommunication.SendStreamData(_ms, TCopyDataType.cdtRecord);
    _AppCommunication.SendRecord(@_rec, System.TypeInfo(TMyRec));
    //_AppCommunication.SendRecord(@_Record, System.TypeInfo(TAttrData));
  finally
    FreeAndNil(_ms);
    FreeAndNil(_AppCommunication);
  end;
end;

问题是如果我一起发送TypeInfo和记录，我在读第二个时失败了。如果我单独发送，我可以阅读TypInfo或记录。我该怎么办才能让它发挥作用？

Answer 1

您不能跨进程边界使用指针，更不用指向RTTI的指针。您不应该将指针发送到TMyRec（当然不是指针到其RTTI）。您需要发送实际 TMyRec本身的副本（您已将代码注释掉以完全相同），例如：

type
  PMyRec = ^TMyRec;
  TMyRec = packed record
    Name: string[255];
    Age: integer;
    Birthday: TDateTime;
  end;

function TAppCommunication.SendRecord(const ARecordToSend: Pointer; ARecordSize: Integer): Boolean;
var
  _Stream: TMemoryStream;
begin
  _Stream := TMemoryStream.Create;
  try
    _Stream.WriteBuffer(ARecordToSend^, ARecordSize);
    _Stream.Position := 0;
    Result := SendStreamData(_Stream, TCopyDataType.cdtRecord);
  finally
    FreeAndNil(_Stream);
  end;
end;

...

// need to cast to WPARAM and LPARAM, not Integer...
_SendResponse := SendMessage(_ReceiverHandle, WM_COPYDATA, WPARAM(FLocalReceiverForm.Handle), LPARAM(@ADataToSend)); 

... 

var
   _Rec: TMyRec;

_Rec.Name := 'Edijs';
_Rec.Age := 29;
_Rec.Birthday := EncodeDate(1988, 10, 06);
_AppCommunication.SendRecord(@_Rec, SizeOf(_Rec));

procedure TReceiverMainForm.OnAppMessageReceived(const ASender : TPair<HWND, string>; const AReceivedData: TCopyDataStruct; var AResult: integer);
var
  _MyRec: PMyRec;
begin
  ....
  else
  begin
    if AReceivedData.dwData = Ord(TCopyDataType.cdtRecord) then
    begin
      memLog.Lines.Add('Record received.');
      _MyRec := PMyRec(AReceivedData.lpData);
      // Use _MyRec^ data as needed...
      ShowMessage(_MyRec.Name + ', Age: ' + IntToStr(_MyRec.Age) + ', birthday: ' + DateToStr(_MyRec.Birthday));
    end else
      memLog.Lines.Add('Unknown data received.');
    AResult := -1;
  end;
end;

如果您需要在相同的cdtRecord ID下发送多种类型的记录，则需要在记录数据之前发送实际记录类型名称（而不是其RTTI），例如：

function TAppCommunication.SendRecord(const ARecordType: ShortString; const ARecordToSend: Pointer; ARecordSize: Integer): Boolean;
var
  _Stream: TMemoryStream;
begin
  _Stream := TMemoryStream.Create;
  try
    _Stream.WriteBuffer(@ARecordType, 1+Length(ARecordType));
    _Stream.WriteBuffer(ARecordToSend^, ARecordSize);
    _Stream.Position := 0;
    Result := SendStreamData(_Stream, TCopyDataType.cdtRecord);
  finally
    FreeAndNil(_Stream);
  end;
end;

var
   _Rec: TMyRec;

_Rec.Name := 'Edijs';
_Rec.Age := 29;
_Rec.Birthday := EncodeDate(1988, 10, 06);
_AppCommunication.SendRecord('TMyRec', @_Rec, SizeOf(_Rec));

procedure TReceiverMainForm.OnAppMessageReceived(const ASender : TPair<HWND, string>; const AReceivedData: TCopyDataStruct; var AResult: integer);
var
  _RecType: ShortString;
  _RecData: Pointer;
  _MyRec: PMyRec;
begin
  ....
  else
  begin
    if AReceivedData.dwData = Ord(TCopyDataType.cdtRecord) then
    begin
      memLog.Lines.Add('Record received.');
      _RecType := PShortString(AReceivedData.lpData)^;
      _RecData := PByte(AReceivedData.lpData)+1+Length(_RecType);
      if (_RetType = 'TMyRec') then
      begin
        _MyRec := PMyRec(_RecData);
        // Use _MyRec^ data as needed...
        ShowMessage(_MyRec.Name + ', Age: ' + IntToStr(_MyRec.Age) + ', birthday: ' + DateToStr(_MyRec.Birthday));
      end
      else
      ...
    end else
      memLog.Lines.Add('Unknown data received.');
    AResult := -1;
  end;
end;

否则，您需要使用更复杂的序列化机制，以更一般化的方式识别您的记录类型和字段。

如何读取其他进程内存

1 个答案: