如何使用 java 在 Windows 操作系统中检测工作站/系统屏幕锁定/解锁？

Question

I'm trying to note down workstation/System screen Lock and Unlock of each employee working in windows OS. I needed to store these record in a DataBase, using JAVA. I have searched all over and got on idea how to do it using JAVA. where ever I searched I get code for VB only.

Answer 1

You can do it in pure Java using JNA . Add jna.jar and jna-platform.jar to your project. And in this file com.sun.jna.platform.win32.Win32WindowDemo there is a full example of lock and unlock listener and much more. Here is the necessary code from thah Win32WindowDemo:

public class WorkstationLockListening implements WindowProc
{

    /**
     * Instantiates a new win32 window test.
     */
    public WorkstationLockListening()
    {
        // define new window class
        final WString windowClass = new WString("MyWindowClass");
        final HMODULE hInst = Kernel32.INSTANCE.GetModuleHandle("");

        WNDCLASSEX wClass = new WNDCLASSEX();
        wClass.hInstance = hInst;
        wClass.lpfnWndProc = WorkstationLockListening.this;
        wClass.lpszClassName = windowClass;

        // register window class
        User32.INSTANCE.RegisterClassEx(wClass);
        getLastError();

        // create new window
        final HWND hWnd = User32.INSTANCE.CreateWindowEx(User32.WS_EX_TOPMOST, windowClass, "'TimeTracker hidden helper window to catch Windows events", 0, 0, 0, 0, 0, null, // WM_DEVICECHANGE contradicts parent=WinUser.HWND_MESSAGE
                null, hInst, null);

        getLastError();
        System.out.println("window sucessfully created! window hwnd: " + hWnd.getPointer().toString());

        Wtsapi32.INSTANCE.WTSRegisterSessionNotification(hWnd, Wtsapi32.NOTIFY_FOR_THIS_SESSION);

        MSG msg = new MSG();
        while (User32.INSTANCE.GetMessage(msg, hWnd, 0, 0) != 0)
        {
            User32.INSTANCE.TranslateMessage(msg);
            User32.INSTANCE.DispatchMessage(msg);
        }

            /// This code is to clean at the end. You can attach it to your custom application shutdown listener
            Wtsapi32.INSTANCE.WTSUnRegisterSessionNotification(hWnd);
            User32.INSTANCE.UnregisterClass(windowClass, hInst);
            User32.INSTANCE.DestroyWindow(hWnd);
            System.out.println("program exit!");
    }

    /*
     * (non-Javadoc)
     * 
     * @see com.sun.jna.platform.win32.User32.WindowProc#callback(com.sun.jna.platform .win32.WinDef.HWND, int, com.sun.jna.platform.win32.WinDef.WPARAM, com.sun.jna.platform.win32.WinDef.LPARAM)
     */
    public LRESULT callback(HWND hwnd, int uMsg, WPARAM wParam, LPARAM lParam)
    {
        switch (uMsg)
        {
            case WinUser.WM_DESTROY:
            {
                User32.INSTANCE.PostQuitMessage(0);
                return new LRESULT(0);
            }
            case WinUser.WM_SESSION_CHANGE:
            {
                this.onSessionChange(wParam, lParam);
                return new LRESULT(0);
            }
            default:
                return User32.INSTANCE.DefWindowProc(hwnd, uMsg, wParam, lParam);
        }
    }

    /**
     * Gets the last error.
     * 
     * @return the last error
     */
    public int getLastError()
    {
        int rc = Kernel32.INSTANCE.GetLastError();

        if (rc != 0)
            System.out.println("error: " + rc);

        return rc;
    }

    /**
     * On session change.
     * 
     * @param wParam
     *            the w param
     * @param lParam
     *            the l param
     */
    protected void onSessionChange(WPARAM wParam, LPARAM lParam)
    {
        switch (wParam.intValue())
        {
            case Wtsapi32.WTS_SESSION_LOCK:
            {
                this.onMachineLocked(lParam.intValue());
                break;
            }
            case Wtsapi32.WTS_SESSION_UNLOCK:
            {
                this.onMachineUnlocked(lParam.intValue());
                break;
            }
        }
    }

    /**
     * On machine locked.
     * 
     * @param sessionId
     *            the session id
     */
    protected void onMachineLocked(int sessionId)
    {
        System.out.println("Machine locked right now!");
    }

    /**
     * On machine unlocked.
     * 
     * @param sessionId
     *            the session id
     */
    protected void onMachineUnlocked(int sessionId)
    {
        System.out.println("Machine unlocked right now!");
    }
}

We have solved this problem in Google Group Workstation Lock / Unlock listener . You can find there my own implementation but this code right here is much better! Enjoy :)

Answer 2

One more way, without any windows system libs, ect.

Main idea - screenshots for locked PC will be totally black, so you can take one and simply check that some critical points are black

-16777216 - magic number, that means FFFFFFFFFF000000xH and last 00 00 00 means RGB color code (actually black color)

        BufferedImage image = new Robot().createScreenCapture(new Rectangle(Toolkit.getDefaultToolkit().getScreenSize()));
        boolean isBlack;    
        isBlack = (image.getRGB(1,1)==-16777216)
                &(image.getRGB(1,image.getHeight()-1)==-16777216)
                &(image.getRGB(image.getWidth()-1,1)==-16777216)
                &(image.getRGB(image.getWidth()-1,image.getHeight()-1)==-16777216)
                &(image.getRGB(image.getWidth()/2,image.getHeight()/2)==-16777216);
        return isBlack;

Actually, there could be only one case with incorrect lock identification - when you have totally black wallpaper, with hidden taskbar and hidden icons.

Answer 3

Use JNI (Java Native Interface) to invoke functions from the Windows system dll.

Here is the sample code for use of functions which check workstation locking state: http://brutaldev.com/post/2008/05/23/Checking-if-the-workstation-is-locked.aspx

And here is the article about invoking dll-functions from Java via JNI: http://edn.embarcadero.com/article/20679

Answer 4

Have a look at Unlock Administrator

The purpose of the program is allow the admin at assign who can unlock the computer but it also has logging capability. It also allows you to run a script whenever the computer is locked or unlocked. This may be helpful to you.

Answer 5

Using JDIC Library,

To Check the system is Locked or Not

SystemInfo.isSessionLocked()

Answer 6

With JDK9 (JDK11) you can use java.awt.Desktop :

Desktop tempDesktop = Desktop.getDesktop(); tempDesktop.addAppEventListener(new UserSessionListener() {

        @Override
        public void userSessionDeactivated(UserSessionEvent aE) {
            LOG.info("Desktop:userSessionDeactivated Reason=" + aE.getReason() + " Source=" + aE.getSource());
            // Windows Key L: 
            // Tue Aug 31 11:22:49 CEST 2021:info:MainController:userSessionDeactivated Reason=LOCK

            // Close Lid:
            // Tue Aug 31 11:24:38 CEST 2021:info:MainController:userSessionDeactivated Reason=LOCK
            // Tue Aug 31 11:24:39 CEST 2021:info:MainController:systemAboutToSleep Source=java.awt.Desktop@741f67cd

            ptcUserStatus = PtcUserStatus.AWAY;

        }

        @Override
        public void userSessionActivated(UserSessionEvent aE) {
            LOG.info("Desktop:userSessionActivated Reason=" + aE.getReason() + " Source=" + aE.getSource());
            // Logon after Windows Key L
            // Tue Aug 31 11:22:53 CEST 2021:info:MainController:userSessionActivated Reason=LOCK

            // Open Lid:
            // Tue Aug 31 11:24:56 CEST 2021:info:MainController:systemAwoke Source=java.awt.Desktop@741f67cd
            // Tue Aug 31 11:25:06 CEST 2021:info:MainController:userSessionActivated Reason=LOCK
            ptcUserStatus = PtcUserStatus.BACK;
        }
    });