I realise that there are other questions on this topic, all of which I have attempted to implement the answers of and failed. I would like to end up with a full blown answer, ideally with a demonstration, on how to, in Windows and only Windows set the desktop background instantly without having the user log in and out or lock and log back in. The approach that involves using the runtime console to push the registry entries about and then rundll32 user32.dll call UpdatePerUserSystemPreferences has yet to work for me. The desired behaviour is achieved when the user right clicks an image file in explorer and selects 'Set as desktop background'. I'd like to do that programatically even if it devolves to the level of opening a hidden explorer window and right-clicking a file in it as long as the user sees nothing of it. The application in question updates the user's desktop background image with useful system information. The image to be used will be generated and regenerated every five seconds.
Can I change my Windows desktop wallpaper programmatically in Java/Groovy?
So the correct way is with JNA if you are not familiar with JNA or if you haven't used JNA the link above is for you. Otherwise you are right about using natives but you never stated how you are using them so I am just taking shots in the dark here.
Related
I'm trying to build a report-building tool (which has a UI written in JavaFX) that has the following features:
When the system (re-)boots, it should auto-start in the background (without showing the UI)
It should have an icon in the system tray
The UI should only show when the user clicks on the system tray icon
A report should be generated either once a day/week/month, at a specific time, automatically
It should "snooze/sleep" in the interim period and use minimal resources while it awaits the next trigger time
It should show a toast pop-up / Windows notification / whatever when a new report has been generated
(The bold ones are the real problems, the italics are maybe solvable--given some resources I found--and the un-formatted one I have a work-around for, namely to place it on in the Startup folder in the AppData folder of the users' machine.)
But the clincher is the following: due to my company's policies, I'm NOT allowed to build register it as a Windows service. Also, converting it into a web service, placing it on a server, and using Control-M (or a cron expression) are also off the table. (That's a long story for another day.) I'm not sure how to implement it and I've been stuck on this for a bit.
I've taken a look at Quartz, this other StackOverflow question, and some other resources on how to run the Java app in the background, but most resources tell me to add it as a Windows service and I keep hitting a brick wall. Also, I don't know how much of an effect the application would have on the users' machines if I ran the application in the background with the solutions mentioned in the other StackOverflow answer. I need to have a minimal processing footprint in the interim period.
I'm also unsure of how to package the application as an EXE. For now, I'm going to turn it into an executable JAR. (Any help on this would also be welcome.)
I'm open to any suggestions and ideas and even other resources to look at for further reading. Anything to help me out here is welcome.
I try to make an application which must be full screen. But when i press CTRL+ALT+DEL task manager comes up. Even i disable task manager, at this time its error message comes up and make taskbar visible. Then user get the chance to go to the dekstop but i dont want user to get this chance. Only user could be able to go to desktop when it did what application wants from it. So i need taskbar keep bottom of other windows until user does what it should do. And i need to do this by my application which i try to code in Java
How can i change the status of task bar using registry?
Why not permanently disable the taskbar?
Follow this link to permanently disable the task bar.
You can edit .reg files in Java, follow This link to know how to edit .reg files
"But how can i do it by java without reseting the machine?"
As far as i came across, you have to reboot your system, no way out.
Ok i found it.
When i changed the value of 8th byte value of Settings variable to 10 in
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\StuckRects2
in registery
It just deselect the "Keep the task bar on top other windows" option
For applying the changes explorer.exe should be killed and re run
There are key strokes which Windows catches before they are sent to application and Ctrl+Alt+Del is one of those.
Regarding "Then user get the chance to go to the dekstop", if you set frame.setAlwaysOnTop(true);, user won't be able to switch to other any application.
You can use java's fullscreen API, and then use a Robot to force focus back to your application. See here: Java Full Screen Program (Swing) -Tab/ALT F4.
Good luck in whatever you are doing - it doesn't sound fun!
I have an applet packaged with a third part dll (from JTwain). My applet scans documents from the TWAIN compatible default printer. The applet fails on a paper jam and won't recover. The user navigates away from the page and the applet is destroyed. When returning to the page it fails again. Closing the browser (which kills java.exe process on the pc), and then returning to the page clears the problem and everything works.
I want to restart everything without requiring users to close down the browser. I've added a GUID query string to the URL's from which the applets resources are loaded - so I know nothing is being cached. I've checked in the windows task manager and there is no process created by the dll, it's all happening within the main java.exe process. I tried wrapping the scanning process in a thread so I could interrupt it in the stop or destroy methods (just in case the applets thread weren't stopped when the applet was destroyed), but that didn't work.
Any suggest would be greatly appreciated. Ideally I'd like some way to restart java when the applet unloads (but I doubt that's possible).
UPDATE
I've spent a couple of days trying to identify what causes the applet to fail. I still don't know :(
When the paper jam occurs something (not my code), is producing a couple of popups. The first alerts the user of the jam, and can be closed by clicking the OK button. The second says 'reading from device' and hangs. It cannot be close with the red, close window, icon in the top corner - I kill it from the task manager and windows asks to send a report regarding the 'non-responsive program'. I assume these popups are produced by the dll. And given that the second hangs, my assumption is that a thread started by the dll has hung while retaining a lock on some component of the TWAIN application. I get
com.asprise.util.jtwain.JTwainException: Failed to open the specified data source:
Source: TW-Brother MFC-9970CDW LAN Thrown
..when I try to access the scanner.
I'm at a bit of a loss as to how I can get more information. I'm testing my applet on a windows virtual pc (so as to use ie7), and don't have a method for step debugging in this environment. (And it's crashing on third party code for which I have no source anyway)
I see only two practical options here:
Use an API that handles paper jam without problems. Of course, that is easy to say (get robust API), harder to find.
Launch the app. free floating using Java Web Start. If it freezes up, the user can kill it and click the link for another instance in a new JVM. Or the applet might also call BasicService.showDocument(URLof.jnlp) if it can detect a problem with the DLL and is not itself frozen.
Of course, you should also report the bug to the ..Asprise(?) developers. The optimal solution would be to have the problem fixed at its source. Anything we do here is a 'workaround'.
I'm trying to capture images by using webcam in an applet. The applet makes use of JMF. But I managed to run applet without actually installing JMF. I kept a button in HTML webpage so that when the button gets clicked, the applet should capture the image.
But for me it is giving a java.lang.RuntimeException: No permission to capture from applets. How can this exception be resolved so an applet can capture image using webcam in HTML page?
In order to capture images in an applet, it is necessary:
For you to digitally sign the code.
For the user to click "OK" when prompted to run the signed code.
If the functionality is being called from a button using JavaScript, wrap the Java code in one of the AccessController.doPrivileged(PrivilegedAction) variants.
AFAIR the installer for JMF does not have the 'allow capture from applets' checked by default. That needs to be reconfigured in the JMF options. I forget how.
Update
I dont want to give client package to extra overhead of the installation of JMF.
That is just silly.
The components of the JMF must be available on the run-time class-path of the applet, for it to function. If they are downloaded by the JRE using the applet element (or whatever), then the user has incurred that 'overhead'.
But perhaps you mean you don't want to make the end user run the installer that advises to 'reboot' at the end. In that case, you are missing my point while avoiding answering my question. That question, again, is "How did you get the DLL?".
Applets run with very limited permissions and that might be causing the issue.. Here is an old post which has information about signing an applet to get the necessary permissions..hope this helps
I think flash is a much better option. There are really easy solutions for that even using Javascript + Flash.
Take a look at this: http://www.xarg.org/project/jquery-webcam-plugin/
This question asked Too many times in this forum..
Anyways..Here is the solution: Java swing Program to capture webcam images
you have to modify it for applet which takes only 30 minutes
Is it possible to get image contents of an obstructed window without bringing it to the front? Also, is it possible to send mouse clicks to a specific locations of such window? I want to do this in Java, using JNA, running Windows XP (if it is possible, would it also work on Windows 7?). If that can be done, would you mind telling me what functions will be needed and where can I read about it, because I have never worked with JNA yet. Thank you.