API文档引用CD刻录作为示例,但同样适用于您的“任务关键型”过程.

Applications should call this function as they begin an operation that cannot be interrupted,such as burning a CD or DVD. When the operation has completed,call the ShutdownBlockReasonDestroy function to indicate that the system can be shut down.

请注意,该文档专门引用了用户关闭,但我不明白为什么它也不应该也适用于更新重启.

注意：记得检查功能是否成功;并在进程完成时销毁关闭原因.

根据您的评论,您似乎需要使用Windows API例程的帮助.我建议你在适当的库中声明外部函数. (但你可以毫无顾虑地在同一个单位进行测试.)

function ShutdownBlockReasonCreate(hWnd: HWND; Reason: LPCWSTR): BOOL; stdcall; external user32;
function ShutdownBlockReasonDestroy(hWnd: HWND): BOOL; stdcall; external user32;

以下演示了如何使用API​​.注意：注意错误检查.我已经演示了如何获取错误信息.你用它做什么取决于你.

要指出的另一个重要的事情(在评论中重复)是你不应该阻止主线程.有关详细信息,请参阅Vista here中首次引入这些更改时的Microsoft文档.

procedure TForm1.JobStartClick(Sender: TObject);
var
  LErr: Cardinal;
begin
  ListBox1.Items.Add('Attempting to block shutdown:');
  if (not ShutdownBlockReasonCreate(Application.MainForm.Handle,'Super Critical Job')) then
  begin
    LErr := GetLastError;
    ListBox1.Items.Add('... Failed: ' + SysErrorMessage(LErr));
    //Probably not safe to start your job in this case,but perhaps you
    //choose to give it a shot anyway.
    Exit;
  end;
  ListBox1.Items.Add('... success');

  FJobRunning := True;
  //Start the job.
  //However,NB do not run the job here.
  //If it takes a long time and is not asynchronous,you should probably
  //run your job on a separate thread.   ***Do not block the main thread
  //  otherwise Windows will still kill your app for not responding***
end;

procedure TForm1.JobEndClick(Sender: TObject);
var
  LErr: Cardinal;
begin
  if (not FJobRunning) then Exit;
  //End the job.
  //Again,do not block the main thread,so perhaps this is rather something
  //to do after you already know the job is done.
  FJobRunning := False;

  ListBox1.Items.Add('Allow shutdown');
  if (not ShutdownBlockReasonDestroy(Application.MainForm.Handle)) then
  begin
    LErr := GetLastError;
    ListBox1.Items.Add('... Failed: ' + SysErrorMessage(LErr));
  end;
end;

//Declare the handler for the WM_QUERYENDSESSION message as follows.
//procedure WMQueryEndSession(var AMsg : TWMQueryEndSession); message WM_QUERYENDSESSION;
procedure TForm1.WMQueryEndSession(var AMsg: TWMQueryEndSession);
begin
  ListBox1.Items.Add('WMQueryEndSession');
  if (FJobRunning) then
    //NB: This is very important.
    //You still need to confirm that your application wants to block
    //shutdown whenever you receive this message.
    AMsg.Result := 0
  else
    inherited;
end;