不是很大，就贴出来了：
unit dirnotify;
interface
uses
Windows, Messages, SysUtils, Classes,
Graphics, Controls, Forms, Dialogs;
type
EDirNotificationError = class(Exception);
TDirNotify = class;
TNotifyFilter = (nfFileName, nfDirName, nfAttributes, nfSize, nfLastWrite,
nfSecurity);
TNotifyFilters = set of TNotifyFilter;
TNotificationThread = class(TThread)
Owner: TDirNotify;
procedure Execute; override;
procedure DoChange;
end;
TDirNotify = class(TComponent)
private
FEnabled: Boolean;
FOnChange: TNotifyEvent;
FNotificationThread: TNotificationThread;
FPath: String;
FWatchSubTree: Boolean;
FFilter: TNotifyFilters;
procedure SetEnabled( Value: Boolean );
procedure SetOnChange( Value: TNotifyEvent );
procedure SetPath( Value: String );
procedure SetWatchSubTree( Value: Boolean );
procedure SetFilter( Value: TNotifyFilters );
procedure RecreateThread;
protected
procedure Change;
procedure Loaded; override;
public
constructor Create(AOwner: TComponent); override;
destructor Destroy; override;
published
property Enabled: Boolean read FEnabled write SetEnabled default True;
property OnChange: TNotifyEvent read FOnChange write SetOnChange;
property Path: String read FPath write SetPath;
property WatchSubTree: Boolean read FWatchSubTree write SetWatchSubTree;
property Filter: TNotifyFilters read FFilter write SetFilter default [nfFileName, nfDirName, nfAttributes, nfLastWrite, nfSecurity];
end;
procedure Register;
implementation
const
LASTERRORTEXTLENGTH = 500;
var
LastErrorText: array [0..LASTERRORTEXTLENGTH] of char;
function GetLastErrorText: PChar;
begin
FormatMessage( FORMAT_MESSAGE_FROM_SYSTEM,
nil, GetLastError, 0, LastErrorText, LASTERRORTEXTLENGTH, nil );
Result := LastErrorText;
end;
procedure TNotificationThread.Execute;
var
h: THandle;
nf: Longint;
wst: LongBool;
begin
nf := 0;
if (nfFileName in Owner.Filter) then nf := FILE_NOTIFY_CHANGE_FILE_NAME;
if (nfDirName in Owner.Filter) then nf := nf or FILE_NOTIFY_CHANGE_DIR_NAME;
if (nfAttributes in Owner.Filter) then nf := nf or FILE_NOTIFY_CHANGE_ATTRIBUTES;
if (nfSize in Owner.Filter) then nf := nf or FILE_NOTIFY_CHANGE_SIZE;
if (nfLastWrite in Owner.Filter) then nf := nf or FILE_NOTIFY_CHANGE_LAST_WRITE;
if (nfSecurity in Owner.Filter) then nf := nf or FILE_NOTIFY_CHANGE_SECURITY;
// yeahh, this one is stupid but Win98 malfunctions in any other value than 0 or 1
if Owner.FWatchSubTree then wst := Longbool(1)
else wst := Longbool(0);
h := FindFirstChangeNotification( Pointer(Owner.Path), wst, nf );
if (h = INVALID_HANDLE_VALUE) then
raise EDirNotificationError.Create( GetLastErrorText );
repeat
if (WaitForSingleObject( h, 1000 ) = WAIT_OBJECT_0) then
begin
Synchronize(DoChange);
if not FindNextChangeNotification( h ) then
raise EDirNotificationError.Create( GetLastErrorText );
end;
until Terminated;
end;
procedure TNotificationThread.DoChange;
begin
Owner.Change;
end;
constructor TDirNotify.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
FEnabled := True;
FFilter := [nfFileName];
end;
destructor TDirNotify.Destroy;
begin
FNotificationThread.Free;
inherited Destroy;
end;
procedure TDirNotify.Loaded;
begin
inherited;
RecreateThread;
end;
procedure TDirNotify.SetEnabled(Value: Boolean);
begin
if Value <> FEnabled then
begin
FEnabled := Value;
RecreateThread;
end;
end;
procedure TDirNotify.SetPath( Value: String );
begin
if Value <> FPath then
begin
FPath := Value;
RecreateThread;
end;
end;
procedure TDirNotify.SetWatchSubTree( Value: Boolean );
begin
if Value <> FWatchSubTree then
begin
FWatchSubTree := Value;
RecreateThread;
end;
end;
procedure TDirNotify.SetFilter( Value: TNotifyFilters );
begin
if Value <> FFilter then
begin
FFilter := Value;
RecreateThread;
end;
end;
procedure TDirNotify.SetOnChange(Value: TNotifyEvent);
begin
FOnChange := Value;
end;
procedure TDirNotify.Change;
begin
if Assigned(FOnChange) then
FOnChange(Self);
end;
procedure TDirNotify.RecreateThread;
begin
// destroy thread
FNotificationThread.Free;
FNotificationThread := nil;
if FEnabled and not(csDesigning in ComponentState)
and not(csLoading in ComponentState) and (FPath <> '') then
begin
// create thread
FNotificationThread := TNotificationThread.Create(True);
FNotificationThread.Owner := self;
FNotificationThread.Resume;
end;
end;
procedure Register;
begin
RegisterComponents('System', [TDirNotify]);
end;
end.
