Is it possible to ask for elevated permissions from within a Java Application? Suggestions I've seen seem to all be centered around running an external executable or setting up a manifest to request privileges on launch. These aren't available to, for instance, applets. Is there any way to request elevation from a running application?
UAC is not something that a running process can request (doesn't matter what language you are running in). You have to request elevation at launch time.
The way that most windows apps handle this (and make it look like they are requesting elevation) is to spawn an extra copy of themselves, requesting elevation, and passing sufficient command line arguments to the new process so that the appropriate dialog can be displayed.
This is why UAC elevation in a dialog is always initiated by a button click that opens a new dialog.
So, in the Java world, you just have to do exactly what everyone else has to do: launch your app again, requesting elevation. There are several ways to launch elevated, the 'run as' verb probably being the easiest.
Looks like Sun will have to handle that kind of situation in the JRE since there's no other way of doing elevated actions than by running an external process.
If JRE supported it, JVM would probably have to run a separate, elevated process for the java code requesting the elevation.
For now however, only the manifest or running an external application are the only solutions available as far as I know.
The question is, what do you need elevation for?
You have to use an external (native) application to do this. This post provides source code and a great explanation:
UAC Prompt From Java
You could use jna and do a ShellExec. For lpOperation use "runas" (this is not documented). Since you likely need the full path to the (current) JavaVM which is stored in the registrylook at registry access, part of JNA.
Goto the folder where java is installed.
open the properties of javaw.exe / java.exe and set "run as administator" option true.
Related
I have a Java application that lives in the system tray that I compile to a executable jar file. I would like to add the option within my program to add to the system startup items.
As I do not know of any uniform way to do this for all operating systems I assumed I would have to write code to do it for each one I intend to support so I started with Windows.
When I attempted to add it to the registry at [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run] using the code available here I discovered that under Windows 7 and 8 unless I have administrator privileges (by running from an elevated command prompt) my edits to the registry do not apply.
Then I spent a day trying to figure out how to get the Jar to relaunch itself with admin privileges before I gave up on that hacky workaround.
Can the task I'm trying to achieve even be accomplished and if so how?
For the most part, you're actually looking to add the feature of auto starting on user login, rather than on system startup. For windows, if you add the registry entry under:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
This location does not suffer from permissions issues when run as an ordinary user, and has been supported for a long time under Windows (I'm thinking Windows 95 time frame here), so should be a safe change across all systems.
For Linux, assuming that the operating system is following the Open Desktop AutoStart specification, then you need to create the appropriate .desktop file in $HOME/.config/autostart/ and it should autostart on login in that case.
For Mac OS X, you need to create a launch agent plist in $HOME/Library/LaunchAgents. The Daemons and services documentation details how to construct this file.
Working around user privileges is not a good idea. The registry entry is the preferred way to go. Also keep in mind that the jar by itself is not executable, it requires the jvm, so what you might want to do is use a wrapper and register that.
Due to a suite of antivirus and security policies, a java applet I developed for my organization loads very slowly. The problem is not the cache or the applet, but rather it's JVM. When Windows first loads, if I go to command window and enter "java", it will take nearly a minute for the response (the command usage text) to come up. Subsequent commands are responded immediately.
So, one mitigation I can think of is to set all users to run java once as they login. I can either put a shortcut to Start Up folder in the start menu, or create a registry key. If I want this to be as least intrusive as possible (load it in background and in low priority), what's the best way to do this?
Did you consider Windows Task Scheduler and task that starts on windows start-up?
You can add the call to java to the registry, under
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
http://msdn.microsoft.com/en-us/library/aa376977(v=vs.85).aspx
But what about not using java?
After spending half a day searching and trying, I'm finally giving up.
I have a java application of which I create a runnable jar (to include any other libs and just have a single jar file). With launch4j and the runnable jar I'm making an executable "MyApp.exe".
The executable ist working fine, but I want to pin it to my windows 7 taskbar. For now, I just have the taskbar entry "Close window".
After reading and implementing the following solutions with JNA
Pinning a Java application to the Windows 7 taskbar
Using JNA to get/set application identifier
my Application displays it's "Application User Model ID" correctly in the gui (just for testing purpose).
BUT: my program is shown as "javaw.exe" in the Task Manager and I still can't pin it to the taskbar, even though I set the launch4j option "custom process name and XP style manifest".
Background information: I'm working with a windows 7 admin account and I don't want the app the require admin rights.
Anyways, if I start the app "as administrator" from the context menu and confirm the UAC message, I can now pin to the taskbar. BUT: even though I set the "Application User Model ID" properly, windows still wants to pin "javaw.exe", even though my program is now shown as "MyApp.exe" in the TaskManager.
I'm totaly confused. But I'm obviously not the only one, having these issues.
=> See the last comments to Gregory Pakosz answer in Using JNA to get/set application identifier
Final questions:
Gregory Pakosz way with JNA to set the "Application User Model ID" ( https://stackoverflow.com/a/1928830/1128689 ) is working for me. But still, windows recognizes my app as an instance of "javaw.exe". What else do I have to do?
Did maybe some windows or java update break something here?
Do I really have to run my app with elevated user rights? I really don't want to...
Are there some more options in launch4j which I have to set?
Do I have to use a manifest file in launch4j?
I got this working by creating an Exe from a runnable jar with the help of JSmooth
.Pinned it to the taskbar, and ran it with no problems.
Hope this helps
No problem with winrun4j either, which is newer and easier to use than Jsmooth
The root cause: javaw is registered as a Host process (in Windows' registry). The shortcut behaviour is probably caused by following (source: Application User Model IDs (AppUserModelIDs))
Application-Defined and System-Defined AppUserModelIDs
Some applications do not declare an explicit AppUserModelID. They are
optional. In that case, the system uses a series of heuristics to
assign an internal AppUserModelID.
[...]
if the process was launched through a shortcut that contains launch
arguments (usually the target content to host as the "application"),
the system can determine identity and the application can be pinned
and relaunched.
About the Host Process behaviour:
Registering an Application as a Host Process
An application can set
the IsHostApp registry entry to cause that executable's process to be
considered a host process by the taskbar. This affects its grouping
and default Jump List entries.
Are you looking for this, which I used in my application to show the running Java application on windows taskbar..
SystemTray systemTray = new SystemTray(composite, parent.getShell(), parent.getDisplay(), "My Application");
systemTray.makeSystemTray();
I'd like to programmatically launch an application (a second JVM) from a Java app using JNA.
Please note that I can't :
add a Windows manifest to the JVM (minimal impact on the client)
use right click "runas administrator" (clicking "Allow" in the UAC dialog will be complicated enough)
I've seen other Questions with answers that states "use an exe" like Java: run as administrator but I was wondering if anybody tried this using JNA
To start an application with elevated privileges, you have to use ShellExecute and pass "runas" as the value of lpOperation parameter. This method does not require you to modify the JVM to add manifest to it. This behaves as if user right-clicked the application and selected Run as administrator command.
Note: on Windows XP, you should not use "runas" because it prompts for user credentials.
We're deploying a Web Start app that I and the other developers know how to install the shortcuts for (Control Panel -> Java on Windows, /Applications/Utilities/Java Preferences on OS X), but we have no reason to believe that end users know how to do this (or even know that it can be done).
Is there a way to either install the shortcuts automatically on first run, or (much preferably) ask the user if they'd like to install the shortcuts? I've been looking all over but the Sun/Oracle docs all say to go through the Java cache viewer, which I find completely ridiculous to ask of end users.
The JNLP specification allows for specifying that short cuts are to be created when the JNLP file is run.
Check the <jnlp><information><shortcut> tag.
The javaws command states:
Usage: javaws [control-options]
control-options include:
....
-import [import-options] <jnlp-file> import the application to the cache
import-options include:
....
-shortcut install shortcuts as if user allowed prompt
so you could probably do it through an invocation of javaws.
As of 1.6.0_18+, JWS offers the IntegrationService.
The IS can not only install/uninstall desktop shortcuts and menu items, but will report the success or failure of attempts to create/remove them.
Some minor points on standard use of shortcuts (through the JNLP file) using Windows and Linux. JWS will prompt the user only if the app. is sand-boxed. If the app. is trusted, it will go ahead and attempt to create the shortcut.
On Ubuntu Linux the menu items will fail silently, but the desk-top shortcut works. I have been meaning to investigate whether Ubuntu menu items will work better using the IS, by targeting the sub-menu to one of the standard sub-menus offered. If that is the case, menu items might be installed by the application targeting different menu structures on different OS'.