监控文件变化

unit FileSysThread;

interface

uses
  Windows, SysUtils, Classes, comctrls;

type
  TFileSysNotifyThread = class(TThread)
  private
    ErrCode: Integer;
    KillAddress: PInteger;
    NotifyHandle: THandle;
    WatchPath: string;
    WatchMask: Integer;
    procedure SignalFileNotification;
  protected
    procedure Execute; override;
  public
    constructor Create(const AWatchPath: string; AWatchMask: Integer; var
      Myself: TFileSysNotifyThread);
    destructor Destroy; override;
  end;

implementation

uses Dialogs;

constructor TFileSysNotifyThread.Create(const AWatchPath: string; AWatchMask:
  Integer; var Myself: TFileSysNotifyThread);
begin
  inherited Create(True);
  WatchPath := AWatchPath;
  WatchMask := AWatchMask;
  KillAddress := Addr(Myself);
  Priority := tpLower;
  FreeOnTerminate := True;
  Suspended := False;
end;

destructor TFileSysNotifyThread.Destroy;
begin
  if NotifyHandle <> THandle(-1) then
    FindCloseChangeNotification(NotifyHandle);
  inherited Destroy;
  KillAddress^ := 0;
end;

procedure TFileSysNotifyThread.Execute;
begin
  NotifyHandle := FindFirstChangeNotification(PChar(WatchPath), False,
    WatchMask);
  if NotifyHandle <> THandle(-1) then
    while not Terminated do
    begin
      ErrCode := WaitForSingleObject(NotifyHandle, 250);
      case ErrCode of
        Wait_Timeout:
          ;
        Wait_Object_0:
          begin
            Synchronize(SignalFileNotification);
            FindNextChangeNotification(NotifyHandle);
          end;
      else
        ;
      end;
    end;
end;

procedure TFileSysNotifyThread.SignalFileNotification;
begin
  ShowMessage('文件已改变!');
end;

end.

unit Test;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls, ComCtrls, ExtCtrls, FileSysThread;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button3: TButton;
    Edit1: TEdit;
    Label1: TLabel;
    procedure Button1Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
  private
    { Private declarations }
    MyThread1: TFileSysNotifyThread;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
begin
  if MyThread1 = nil then
    MyThread1 := TFileSysNotifyThread.Create(edit1.text,
      File_Notify_Change_File_Name or File_Notify_Change_Dir_Name, MyThread1)
  else
    ShowMessage('线程正在运行');
end;

procedure TForm1.Button3Click(Sender: TObject);
begin
  if MyThread1 <> nil then
    MyThread1.Terminate
  else
    ShowMessage('线程未运行');
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  if MyThread1 <> nil then
  begin
    MyThread1.Terminate;
    MyThread1.WaitFor;
  end;
end;

end.