明天去坐火車,回家,今天就沒有事做,本來在弄一個跨進程獲取其他程序里面組件,如ListView,ListBox,Button等的信息,突然有個想法自己寫個Timer,不用SetTimer函數,我們自己用個多線程也正好實現這個.反正前段時間多線程也弄得比較多,本來想單獨講講的,現在就用個例子來說明吧.
寫成一個控件:utTimer.pas
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unit
utTimer;
interface
uses
Windows,SysUtils,Classes;
type
THuangJackyTimerThread =
class
;
THuangJackyTimer =
class
(TComponent)
private
FTimeInterval:
Integer
;
FOnTimerDo:TNotifyEvent;
FTimerThread:THuangJackyTimerThread;
FEnable:
Boolean
;
procedure
SetEnable(bBool:
Boolean
);
procedure
SetTimeInterval(aValue:
Integer
);
procedure
StopThread;
procedure
StartThread;
public
constructor
Create(AOwner: TComponent); override;
destructor
Destroy; override;
published
property
TimeInterval:
Integer
read FTimeInterval
write
SetTimeInterval;
property
OnTimerDo:TNotifyEvent read FOnTimerDo
write
FOnTimerDo;
property
Enable:
Boolean
read FEnable
write
SetEnable;
end
;
THuangJackyTimerThread =
class
(TThread)
private
FTimer:THuangJackyTimer;
FTerminateHandle,FExitHandle,FStartHandle,FStopHandle:
Cardinal
;
procedure
DoTimerEvent;
protected
procedure
Execute;override;
public
constructor
Create(AOwner: THuangJackyTimer);
destructor
Destroy; override;
end
;
procedure
Register;
implementation
procedure
Register;
begin
RegisterComponents(
'HuangJacky'
,[THuangJackyTimer]);
end
;
{ THuangJackyTimer }
constructor
THuangJackyTimer
.
Create(AOwner: TComponent);
begin
inherited
;
FTimeInterval:=
1000
;
FTimerThread:=THuangJackyTimerThread
.
Create(Self);
FTimerThread
.
Resume;
end
;
destructor
THuangJackyTimer
.
Destroy;
begin
SetEvent(FTimerThread
.
FTerminateHandle);
WaitForSingleObject(FTimerThread
.
FExitHandle,
5000
);
FTimerThread
.
Free;
inherited
;
end
;
procedure
THuangJackyTimer
.
SetEnable(bBool:
Boolean
);
begin
if
Enable = bBool
then
Exit;
if
csDesigning
in
ComponentState
then
Exit;
if
Enable
then
begin
StopThread;
FEnable:=
False
;
end
else
begin
StartThread;
FEnable:=
True
;
end
;
end
;
procedure
THuangJackyTimer
.
SetTimeInterval(aValue:
Integer
);
begin
if
FTimeInterval = aValue
then
Exit;
InterlockedExchange(FTimeInterval,aValue);
end
;
procedure
THuangJackyTimer
.
StartThread;
begin
SetEvent(FTimerThread
.
FStartHandle);
end
;
procedure
THuangJackyTimer
.
StopThread;
begin
SetEvent(FTimerThread
.
FStopHandle)
end
;
{ THuangJackyTimerThread }
constructor
THuangJackyTimerThread
.
Create(AOwner: THuangJackyTimer);
var
sTmp,sTmp1:
string
;
begin
inherited
Create(
True
);
Assert(Assigned(AOwner));
//自己創建,自己釋放,這樣能保證100%不內存泄露,個人習慣
FreeOnTerminate:=
False
;
FTimer:=AOwner;
sTmp:=FTimer
.
Name;
sTmp1:=DateTimeToStr(Now());
FTerminateHandle:=CreateEvent(
nil
,
True
,
False
,
PChar
(sTmp + sTmp1 +
'T'
));
Assert(FTerminateHandle<>
0
);
//用這個Event來通知主線程:Timer線程已經執行完了
FExitHandle:=CreateEvent(
nil
,
True
,
False
,
PChar
(sTmp + sTmp1 +
'E'
));
Assert(FExitHandle<>
0
);
FStartHandle:=CreateEvent(
nil
,
True
,
False
,
PChar
(sTmp + sTmp1 +
'Sa'
));
Assert(FStartHandle<>
0
);
FStopHandle:=CreateEvent(
nil
,
True
,
False
,
PChar
(sTmp + sTmp1 +
'So'
));
Assert(FStopHandle<>
0
);
end
;
destructor
THuangJackyTimerThread
.
Destroy;
begin
CloseHandle(FStopHandle);
CloseHandle(FStartHandle);
CloseHandle(FExitHandle);
CloseHandle(FTerminateHandle);
inherited
;
end
;
procedure
THuangJackyTimerThread
.
DoTimerEvent;
begin
if
Assigned(FTimer
.
OnTimerDo)
then
FTimer
.
OnTimerDo(FTimer);
end
;
procedure
THuangJackyTimerThread
.
Execute;
var
Waits1:
array
[
0..2
]
of
Cardinal
;
Waits2:
array
[
0..1
]
of
Cardinal
;
procedure
DoTerminate;
begin
ResetEvent(FTerminateHandle);
Terminate;
end
;
begin
Waits1[
0
]:=FStartHandle;
Waits1[
1
]:=FTerminateHandle;
Waits1[
2
]:=FStopHandle;
Waits2[
0
]:=FStopHandle;
Waits2[
1
]:=FTerminateHandle;
//循環等待.
while
not
Terminated
do
//每一次Wait后我們都需要判斷下Terminate,不然在你等待的時候,線程就被Terminate了.
//不過不判斷也不要緊
//因為Terminate只是將Terminated設置成True.
//也就是如果不判斷,就多運行一次.
//但是這個例子里面因為內層也有一個While循環,所以必須判斷
case
WaitForMultipleObjects(
3
,@Waits1,
False
,INFINITE)
of
WAIT_OBJECT_0 +
0
:
begin
ResetEvent(FStartHandle);
if
Terminated
then
Break;
while
True
do
begin
case
WaitForMultipleObjects(
2
,@Waits2,
False
,FTimer
.
TimeInterval)
of
WAIT_OBJECT_0 +
0
:
begin
ResetEvent(FStopHandle);
Break
end
;
WAIT_OBJECT_0 +
1
:
begin
DoTerminate;
Break;
end
;
end
;
if
Terminated
then
Break;
//執行Timer事件.
Synchronize(DoTimerEvent);
end
;
end
;
WAIT_OBJECT_0 +
1
:
DoTerminate;
WAIT_OBJECT_0 +
2
:
ResetEvent(FStopHandle);
end
;
SetEvent(FExitHandle);
end
;
end
.
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兩百行的代碼,比較簡單,就是一個線程在循環等待事件,然后相應的事件做相應的事.
其實主要是想說如何使用線程,我不喜歡將線程的FreeOnTerminate設置為True,因為感覺不安全,心里不踏實呀.
測試例子:Unit1.pas
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unit
Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs,utTimer;
type
TForm1 =
class
(TForm)
procedure
FormCreate(Sender: TObject);
private
{ Private declarations }
Timer:THuangJackyTimer;
III:
Integer
;
procedure
DoTimer(S:TObject);
public
{ Public declarations }
end
;
var
Form1: TForm1;
implementation
{$R *.dfm}
procedure
TForm1
.
DoTimer(S: TObject);
begin
//這個Timer不存在重入的情況,所以不需要先設置Enable為True
Caption:=IntToStr(III);
Inc(III);
end
;
procedure
TForm1
.
FormCreate(Sender: TObject);
begin
Timer:=THuangJackyTimer
.
Create(Self);
Timer
.
TimeInterval:=
2000
;
Timer
.
OnTimerDo:=DoTimer;
Timer
.
Enable:=
True
;
end
;
end
.
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D7和D2010上面都測試了一下,米有發現問題.
如果有什么問題歡迎拍磚.哈哈
http://www.cnblogs.com/huangjacky/archive/2010/02/10/1667217.html