相关资料：
/html/xiancheng/376.html
1 unit Unit1; 2 3 interface 4 5 uses 6 Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics, 7 Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls; 8 9 type10 TMyThread = class(TThread)//自定义的线程11 protected12procedure Execute; override;13 end;14 15 TForm1 = class(TForm)16Button1: TButton;17procedure Button1Click(Sender: TObject);18 private19{Private declarations }20 public21{Public declarations }22 end;23 24 var25 Form1: TForm1;26 mytd: TMyThread;//线程对像27 implementation28 29 {$R *.dfm}30 31 //返回值：0-已释放；1-正在运行；2-已终止但未释放；3-未建立或不存在32 function CheckThreadFreed(aThread: TThread): Byte;33 var34 I: DWord;35 IsQuit: Boolean;36 begin37 if Assigned(aThread) then38 begin39IsQuit := GetExitCodeThread(aThread.Handle, I);40if IsQuit then //If the function succeeds, the return value is nonzero.41//If the function fails, the return value is zero.42begin43 if I = STILL_ACTIVE then //If the specified thread has not terminated,44 //the termination status returned is STILL_ACTIVE.45 Result := 146else47 Result := 2; //aThread未Free，因为Tthread.Destroy中有执行语句48end49else50Result := 0; //可以用GetLastError取得错误代码51 end52 else53 Result := 3;54 end;55 56 procedure TMyThread.Execute;57 var58 I: Integer;59 begin60 for I := 0 to 500000 do61 begin62Form1.Canvas.Lock;63Form1.Canvas.TextOut(10, 10, IntToStr(I));64Form1.Canvas.Unlock;65 end;66 end;67 68 procedure TForm1.Button1Click(Sender: TObject);69 begin70 if CheckThreadFreed(mytd)<>1 then //判断线程是否存在71 begin72mytd := TMyThread.Create(True);73mytd.FreeOnTerminate := True;74mytd.Resume;75 end;76 end;77 78 end.
View Code
