利用WM_COPYDATA进行进程间单向通信

一：发送方

var
  hwnd:THandle;
  cpStruct:COPYDATASTRUCT;
begin
  hwnd:=FindWindow(nil,PChar(FORMNAME));
  if hwnd<>0 then
  begin
    cpStruct.dwData:=0;
    cpStruct.cbData:=length('test')+1;
    cpStruct.lpData:=pchar('test');
    SendMessage(Handle,WM_COPYDATA,0,Cardinal(@cpStruct));//lParam和wParam的顺序不能交换，具体原因还未找到
  end;
end;

二：接收方

procedure WMCopyData(var Message: TWMCopyData); message WM_COPYDATA;

procedure TForm1.WMCopyData(var Message: TWMCopyData);
begin
  if message.Msg=WM_COPYDATA then
    Self.Text:=PChar(message.CopyDataStruct.lpData)
  else
    ShowMessage('方法不对');
end;