C＃Windows服务在安装后不返回剪贴板数据

Question

I have this code for a windows service program that should clear the clipboard every now and then. Testing it in a console app proved it is a working code (then turned the console app into service via Topshelf nuget package). But running it as a service it just won't do the job. After some basic logging, I found that the Clipboard.Hastext() (and all the others) return false after installing the service (directly installed from the debug folder). What did I miss or what is the difference between debug and deployed mode that should be considered?

    public class Service
    {
        readonly Timer timer;
        object clipboardData;

        public Service()
        {
            timer = new Timer(TimeSpan.FromMinutes(1).TotalMilliseconds)
            {
                AutoReset = true
            };
            timer.Elapsed += Timer_Elapsed;
        }

        /// <summary>
        /// Checks every minute if there is any data on the clipboard.
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Timer_Elapsed(object sender, ElapsedEventArgs e)
        {
            CurrentThreadParse(DoWork);
        }

        public void Start()
        {
            timer.Start();
        }

        public void Stop()
        {
            timer.Stop();
        }

        private void ChangeClipboardData()
        {
            if (Clipboard.ContainsText())
            {
                clipboardData = Clipboard.GetText();
                WriteChanged();
            }
            else if (Clipboard.ContainsImage())
            {
                clipboardData = Clipboard.GetImage();
                WriteChanged();
            }
            else if (Clipboard.ContainsAudio())
            {
                clipboardData = Clipboard.GetAudioStream();
                WriteChanged();
            }
            else if (Clipboard.ContainsFileDropList())
            {
                clipboardData = Clipboard.GetFileDropList();
                WriteChanged();
            }
#if DEBUG
            else
                Console.WriteLine("No change!");
#endif
        }

        private void WriteChanged()
        {
#if DEBUG
            Console.WriteLine("Clipboard data has changed!");
#endif
        }

        private object GetClipboardObject()
        {
            if (Clipboard.ContainsText())
                return Clipboard.GetText();
            else if (Clipboard.ContainsImage())
                return Clipboard.GetImage();
            else if (Clipboard.ContainsAudio())
                return Clipboard.GetAudioStream();
            else if (Clipboard.ContainsFileDropList())
                return Clipboard.GetFileDropList();
            return null;
        }

        private void ClearClipboard()
        {
            Clipboard.Clear();
            clipboardData = null;
#if DEBUG
            Console.WriteLine("Clipboard data removed!");
#endif
        }

        /// <summary>
        /// Sets the current thread as STA.
        /// </summary>
        /// <param name="threadStart">The code to run.</param>
        private void CurrentThreadParse(ThreadStart threadStart)
        {
            Thread thread = new Thread(threadStart);
            thread.SetApartmentState(ApartmentState.STA);
            thread.Start();
            thread.Join();
        }

        private void DoWork()
        {
            object clipboardObject = GetClipboardObject();
            if (clipboardData == null)
            {
                ChangeClipboardData();
            }
            else if (clipboardData.Equals(clipboardObject))
            {
                ClearClipboard();
            }
            else
            {
                //The last check returned data from the clipboard, but was changed,
                //so the clipboard should not be cleared.
                ChangeClipboardData();
            }
        }
    }

Full project can be found here: https://github.com/profgyuri/ClipboardService

Answer 1

It's not possible with a service.

Services are running in a separate session on Windows (session 0). Users are in different sessions always (session 1, 2, etc). User's clipboards cannot be accessed by services from another session.

Instead you may create a Windows Schedule task to be executed in user session, a Run only when user is logged on task ( link ). Schedule may have any repeat interval.