关于禁止程序重复启动的另一种需要与实现《转》

程序需要禁止重复启动, 但需要保留新的、关闭旧的.
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从主窗口的类名下手吧; 写了一个函数, 在 OnCreate 中调用即可:

{ 函数 }
procedure CloseSameClassNameWindow(ACurrentWindow: HWND; const AClassName: string);
var
  h: HWND;
  buf: array[0..255] of Char;
begin
  h := ACurrentWindow;
  while h > 0 do
  begin
    h := GetWindow(h, GW_HWNDNEXT);
    GetClassName(h, buf, Length(buf));
    if buf = AClassName then
    begin
      SendMessage(h, WM_CLOSE, 0, 0);
      Break;
    end;
  end;
end;

{ 调用 }
procedure TForm1.FormCreate(Sender: TObject);
begin
  CloseSameClassNameWindow(Handle, ClassName);
end;

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从程序文件中控制更简单, 一句话:

program Project1;

uses
  Forms, Windows, Messages,
  Unit1 in 'Unit1.pas' {Form1};

{$R *.res}

begin
  Application.Initialize;
  SendMessage(FindWindow('TForm1', nil), WM_CLOSE, 0, 0); //假如主窗体的类名是 TForm1
  Application.MainFormOnTaskbar := True;
  Application.CreateForm(TForm1, Form1);
  Application.Run;
end.