动态增长的文本文件的打开问题，请高手指点，就这点分，全给

Question

我有一台称量仪表，软件是厂家做的，称量记录在一个文本文件中，是按照顺序追加到文本文件中，一条称量数据作为一行追加到文本文件的尾部，我现在想这样，如果有新内容加到文本文件中，我就取最后一行，也就是最新的记录，现在的问题是：我不想通过文件字节大小和更新时间来判断文件是否有更新，我想有没有一个办法就像数据库中的触发器一样，也就是说如果这个文件内容变了，就触发，请各位高手指点啊，谢谢谢谢谢谢

Answer 1

定时用GetFileSize看看大小是否改变就可以啦。

Answer 2

问题：我想知道一个文件是否被改变，如何监视？一个方法是使用Timer不停监测，这样不精确并且来非CPU时间，那么有没有更好的方法呢？ 
来自Luke有：TFileChangeNotificationStatus=(fnsIdle,fnsError,fnsRunning);TFileChangeNotification=recordPathName:string;WatchSubtree:boolean;NotifyFilter:DWORD;Status:TFileChangeNotificationStatus;Changes:DWORD;wndHandle:HWND;NotificationMessage:DWORD;end;　TFileChangesMultipleWatcher = class(TThread)private{ Private declarations }FMutex:integer;FObjectsArray:array[0..(WAITOBJECTSCOUNT-1)]of integer;protectedprocedure Execute; override;publicNotification:TFileChangeNotification;constructor Create(Suspended:boolean);destructor Destroy; override;procedure Init;procedure Stop;end;　constructor TFileChangesMultipleWatcher.Create;var guid:TGUID;begininherited;coCreateGuid(guid);FMutex:=CreateMutex(nil,False,PChar('TFCMW.'+GuidToString(guid)));WaitForSingleObject(FMutex,INFINITE);if FMutex<>0 then FObjectsArray[0]:=FMutex;FreeOnTerminate:=True;end;//destructor TFileChangesMultipleWatcher.Destroy;begininherited;{$ifdef DEBUGGING_FILECHANGES} writeln(Notification.PathName,' -DESTROY'); {$endif}end;//procedure TFileChangesMultipleWatcher.Init;beginwith Notification do beginPathName:='';WatchSubtree:=False;NotifyFilter:=0;Status:=fnsIdle;Changes:=0;wndHandle:=0;NotificationMessage:=WM_USER;end;end;//procedure TFileChangesMultipleWatcher.Stop;beginTerminate;ReleaseMutex(FMutex);end;//procedure TFileChangesMultipleWatcher.Execute;var WaitStatus,hChanges:DWORD;Go:boolean;begintry while (not Terminated) do beginwith Notification do beginhChanges:=FindFirstChangeNotification(PChar(PathName),WatchSubtree,NotifyFilter);{$ifdef DEBUGGING_FILECHANGES} writeln('Notification Handle is',hChanges); {$endif}if (hChanges<>INVALID_HANDLE_VALUE) then tryFObjectsArray[1]:=hChanges;Status:=fnsRunning;Go:=True;while (Go) do begin{$ifdef DEBUGGING_FILECHANGES} writeln('WaitForSingleObject');{$endif}WaitStatus:=WaitForMultipleObjects(WAITOBJECTSCOUNT,@FObjectsArray,False,INFINITE);file://if Terminated then exit;case WaitStatus ofWAIT_ABANDONED:begin{$ifdef DEBUGGING_FILECHANGES} writeln('WAIT_ABANDONED');{$endif}end;WAIT_OBJECT_0:beginexit;{$ifdef DEBUGGING_FILECHANGES} writeln('WAIT_OBJECT_0');{$endif}end;WAIT_OBJECT_0+1:begininc(Changes);if (wndHandle<>0) thenPostMessage(wndHandle,NotificationMessage,Changes,NotificationMessage+Changes);{$ifdef DEBUGGING_FILECHANGES} writeln('WAIT_OBJECT_1');{$endif}end;WAIT_TIMEOUT:begin{$ifdef DEBUGGING_FILECHANGES} writeln('WAIT_TIMEOUT');{$endif}end;end;Sleep(100);Go:=FindNextChangeNotification(hChanges);end;finally{$ifdef DEBUGGING_FILECHANGES} writeln('FINALLY 1'); {$endif}FindCloseChangeNotification(hChanges);end else beginStatus:=fnsError;{$ifdef DEBUGGING_FILECHANGES} writeln('STATUS ERROR'); {$endif}end;end;end;finally{$ifdef DEBUGGING_FILECHANGES} writeln('FINALLY 2'); {$endif}ReleaseMutex(FMutex);end;{$ifdef DEBUGGING_FILECHANGES} writeln('BYE!'); {$endif}end;//