delphi判断线程是否正在运行

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http://www.delphitop.com/html/xiancheng/376.html

 unit Unit1;

 interface

 uses
   Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
   Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;

 type
   TMyThread = class(TThread)//自定义的线程
   protected
     procedure Execute; override;
   end;

   TForm1 = class(TForm)
     Button1: TButton;
     procedure Button1Click(Sender: TObject);
   private
     { Private declarations }
   public
     { Public declarations }
   end;

 var
   Form1: TForm1;
   mytd: TMyThread;//线程对像
 implementation

 {$R *.dfm}

 //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
 function CheckThreadFreed(aThread: TThread): Byte;
 var
   I: DWord;
   IsQuit: Boolean;
 begin
   if Assigned(aThread) then
   begin
     IsQuit := GetExitCodeThread(aThread.Handle, I);
     if IsQuit then //If the function succeeds, the return value is nonzero.
     //If the function fails, the return value is zero.
     begin
       if I = STILL_ACTIVE then //If the specified thread has not terminated,
       //the termination status returned is STILL_ACTIVE.
       Result :=
     else
       Result := ; //aThread未Free，因为Tthread.Destroy中有执行语句
     end
     else
     Result := ; //可以用GetLastError取得错误代码
   end
   else
   Result := ;
 end;

 procedure TMyThread.Execute;
 var
  I: Integer;
 begin
   for I :=  to  do
   begin
     Form1.Canvas.Lock;
     Form1.Canvas.TextOut(, , IntToStr(I));
     Form1.Canvas.Unlock;
   end;
 end;

 procedure TForm1.Button1Click(Sender: TObject);
 begin
   if CheckThreadFreed(mytd)<> then //判断线程是否存在
   begin
     mytd := TMyThread.Create(True);
     mytd.FreeOnTerminate := True;
     mytd.Resume;
   end;
 end;

 end.