明天去坐火车,回家,今天就没有事做,本来在弄一个跨进程获取其他程序里面组件,如ListView,ListBox,Button等的信息,突然有个想法自己写个Timer,不用SetTimer函数,我们自己用个多线程也正好实现这个.反正前段时间多线程也弄得比较多,本来想单独讲讲的,现在就用个例子来说明吧.
写成一个控件:utTimer.pas
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unit utTimer;interfaceuses 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;implementationprocedure 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)); //自己创建,自己释放,这样能保证100%不内存泄露,个人习惯 FreeOnTerminate:=False; FTimer:=AOwner; sTmp:=FTimer.Name; sTmp1:=DateTimeToStr(Now()); FTerminateHandle:=CreateEvent(nil,True,False,PChar(sTmp + sTmp1 + 'T')); Assert(FTerminateHandle<>0); //用这个Event来通知主线程:Timer线程已经执行完了 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; //循环等待. while not Terminated do //每一次Wait后我们都需要判断下Terminate,不然在你等待的时候,线程就被Terminate了. //不过不判断也不要紧 //因为Terminate只是将Terminated设置成True. //也就是如果不判断,就多运行一次. //但是这个例子里面因为内层也有一个While循环,所以必须判断 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; //执行Timer事件. Synchronize(DoTimerEvent); end; end; WAIT_OBJECT_0 + 1: DoTerminate; WAIT_OBJECT_0 + 2: ResetEvent(FStopHandle); end; SetEvent(FExitHandle);end;end. |
两百行的代码,比较简单,就是一个线程在循环等待事件,然后相应的事件做相应的事.
其实主要是想说如何使用线程,我不喜欢将线程的FreeOnTerminate设置为True,因为感觉不安全,心里不踏实呀.
测试例子:Unit1.pas
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unit Unit1;interfaceuses 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//这个Timer不存在重入的情况,所以不需要先设置Enable为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. |
D7和D2010上面都测试了一下,米有发现问题.
如果有什么问题欢迎拍砖.哈哈
http://www.cnblogs.com/huangjacky/archive/2010/02/10/1667217.html