unit Unit1;

interface

uses

 Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,Dialogs, StdCtrls;

const

 TIMER_ID = ;

type

 TForm1 = class(TForm)

    Label1: TLabel;

    btkilltime: TButton;

    btsettime: TButton;

    procedure Button1Click(Sender: TObject);

    procedure btkilltimeClick(Sender: TObject);

    procedure btsettimeClick(Sender: TObject);

 private

    { Private declarations }

 public

{ Public declarations }

// WM_TIMECHANGE只在用户手动改变系统时间时才会产生作用，且只需直接定义就起作用。

procedure WMTIMECHANGE(var Message: TWMTIMECHANGE); message WM_TIMECHANGE;

// WM_TIMER需配合KillTimer和SetTimer才能起作用；它保持与系统时间同步触发事件；

    procedure WMTimer(var Message: TWMTimer); message WM_TIMER;

 end;

var

 Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.WMTIMECHANGE(var Message: TWMTIMECHANGE);

begin

 ShowMessage('sss');

end;

procedure TForm1.WMTimer(var Message: TWMTimer);

begin

   Label1.Caption:=TimeToStr(now);

end;

procedure TForm1.btkilltimeClick(Sender: TObject);

begin

// KillTimer作用：向WINDOWS删除时间消息；参数200必须与SetTimer中参数200保持一致，此参数代表所注册的消息ID；

KillTimer(self.Handle, ); // KillTimer(self.Handle, TIMER_ID);

end;

procedure TForm1.btsettimeClick(Sender: TObject);

begin

   // SetTimer作用：向WINDOWS注册时间消息；参数1000代表每隔1秒触发一次WM_TIMER消息；

 SetTimer(self.Handle, , , nil); // SetTimer(self.Handle, TIMER_ID, , nil);

end;

end.