I have a client who has a java based game which he wants to make available online (at the moment it is desktop version which he had to install). He asked me whether I can embed it into a webpage. After trying for several days still no joy. Can you please point me to the right direction. It have fives jar files(executable jar file) and a folder called lib which has five more jar files. Now I don't know whether it is possible to embed the game using applet/object tag. Can you please point me what to look at when dealing with these jar files.
..at the moment it is desktop version which he had to install..
Launch it from a link using Java Web Start. It might be necessary to digitally sign the Jars (what does the app. do?).
Note that a 'desktop application' would typically be coded using a JFrame, whereas the equivalent top-level container for embedding is a JApplet. A frame cannot simply be embedded in a web page.
As the rest of the problems mentioned, you'll need to be a lot more specific about what you tried and the results of those attempts, or find some psychic helpers.
Related
It is as simple as an application that can update itself.
More specific, maybe a launcher that loads a jar file from the web and replaces it with the current jar.
The approach that I want is:
A launcher which is coded in Java.
That launcher overall uses classloader e.t.c.
I want to keep the data from the previous jar. Maybe the data from the previous jar are written on a .txt file and pass them to the new one? (If possible)
I have no clue about classloader or any direction to follow.
So my question is "How can i use classloader to create an auto-update Java application?".
P.S. I want java web start to be the last choice. Some lines of code would help me very much.
Edit: I understand completely what are you saying in theory. What i am looking for is specific links or code which i can take as reference.
The question isn't a duplicate because i can't find links or code but theory.
You can use the URLClassLoader to load a jar file from an URL. Mind, URLs may also be local files, and I'd recommend that you download the jar file locally before loading it in, instead of loading it directly from the web. The reason for this is that you want the application to remain usable, even if the user cannot reach your server.
However, I'd also recommend against taking this approach. What if you want to update the launcher? It's better to download a seperate updater application from the main application, launch the seperate updater application, have that kill the main application and update it.
I have been using IntelliJ for a while now and I'm enjoying its suite of features but I'm having a hard time getting the run configurations to work for a java applet. I have a pre-existing Java tool that uses Swing and I'm using the JApplet class to load those GUI objects as an applet. The problem is I have a couple configuration files that I need loaded. I load these from the working directory and from my knowledge, this working directory would normally be the directory in which the applet resides. I think the major problem is IDEA sets the startup variable:
-Didea.launcher.bin.path=IDEA_BIN_DIR
I would like to be able to change this but I am seemingly unable to. I have tried overriding this flag by editing the applets run configuration VM parameters, but IDEA will continue putting the above one in even if I specify something different.
So in short, I'm having a hard time loading a local configuration file because I can't set the working directory for the run configuration in IDEA. Does anyone know how to get around this or know of a better way of running Java applets that use configuration files, in IDEA?
An applet normally runs in a sandbox in a browser, and such an applet can't access the local computer's file system, for security reasons.
Thus it is generally a bad idea to load configuration files from the file system, and "working directory" is not a useful term for an applet.
If these files change seldom (i.e. in principle only by the developer), you can put them to the applet's class files (i.e. in the jar file, or during development in the directory where the classes will be generated), and use class.getResource() or .getResourceAsStream() to load them.
If the configuration files should be definable by the webmaster, put them on the webserver - either at some fixed location relative to getCodeBase() or .getDocumentBase(), or specify them as parameters to your applet tag in the HTML tag.
If these are user specific configuration files (which the applet should be able to write), you either need to store them on the server and retrieve/store after a login (i.e. you need some logic at the server side), or you would store them at the client side.
The current way to do this would be using the JNLP API (in javax.jnlp.*) - there are some interfaces allowing Persistence, or loading/storing data (with the user having a FileChooser). Alternatively, you could sign your applet and request an AllPermission from the user - then you can access the file system.
Sorry, nothing of these answers your original question (I don't use IDEA), but maybe these help you to find another way.
i want to embed an open source editor to my java desktop application. But i am not sure yet how to do it. I got jnlp web start and jar file to import library.
The program which will be imported is like below.
In fact i just need internal frames but if it is too completed i can embed whole program too.
I think about 3 options but don't know which one really works and which one is better.
Run jnlp webstart in java code
Run jar file in java code(non-executable jar)
Import jar and use its api (This is really what i need but i m not sure how to do this. I debugged the code to understand which frame works how but i have no experience about it and i found it very complicated)
Any advices how to solve this problem ?
Thanks,
Bilal
The picture just shows the view but there's more behind. You can't just embed the internal frames into you application and use the editors functionality. You'll need all the model, controller, support, ... classes too.
You may be lucky, that the main frame is just a simple container and you can "replace" it with your own container. But I not too optimistic. I don't think, that the editor has an API that allows integrating the internal frames into another container. So Option 3 would be the best but I think it's out of reach. Is it a common editor? Maybe more help is possible if you just tell us its name.
I am currently working on desktop software based on java.It's quite a big code base (more than 40 jar files).
I wish to provide an automatic update functionality. The desktop software constantly checks one back end system to see if there are new versions of the jar files available.
The problem now is: How to replace the updated jar files?
If you deploy your application using Java Webstart (JNLP), you get this mechanism almost for free...
From http://mindprod.com/jgloss/javawebstart.html
The key benefit for Java Web Start is automatic update without having to download the entire program every time.
Easiest would be to check for updates on each startup, download the updates and then launch your application. I think this is the way that Java Web Start works (see aioobes answer).
More complex would be to use either the netbeans or eclipse framework for your application. Both are rather complex and you will have to rewrite your application to work with them. This solution supports live updates.
As far as I am aware there is no easy way to update a running application. It is possible to load new versions of a class with a different classloader, but not possible to unload old versions while they are still referenced.
You can make a little server and a launcher which downloads the newest version, replaces the old one, and starts the jar with:
Runtime.getRuntime().exec("java yourjar -jar");
And you terminate the launcher with:
System.exit(1)
You can also serialize down your state (keep it in memory) and then create a new ClassLoader instance pointing to the new .jar files. Then serialize up your state again using this new classloader. You have just changed the underlaying .jars within a executing product.
Please note that you do not need to change the classloader for everything only for the part that is actually using the .jar files. This can be tricky to conclude what parts that are. And you might get nasty linking errors if done wrongly. So..
.. to keep it simple, use WebStart or a preloader that updates the .jars and then starts the main app (basically what WebStart does for you).
A reason for rolling your own, is that you can use your own format for the .jars, encryption, other packing formats etc.
After reading some answers to many auto-update questions, I thought of a solution. This is how I would implement a secure auto-update for a Java/Kotlin jar application.
Assumption: the installer will contain two jars: a launcher and the main application. Any shortcuts created will point to the launcher, but still be the name of the application. The release will contain the main application and the installer.
The launcher is launched first:
First check if an update has already been downloaded as app_name_update.jar
if an update has been downloaded, rename app_name_update.jar to app_name.jar
Start app_name.jar
This part does not have to be in the launcher, but it's preferred as to not slow down the main application: at this point, the launcher should check for an update (e.g. GitHub releases API) and download it to {CWD}/unverified_app_name_update.jar.
Compare the hash of unverified_app_name_update.jar to an online location containing hashes for all published versions. hashes.txt would be an example found in the same github repository. If the software is open-source, GPG signed commits is a must and the launcher should check if the latest update is a verified commit! If its a proprietary application, keep the hashes.txt at a separate URL from the release where your company does not control the infrastructure (e.g. GitHub).
Main app launched:
No need to check for updates unless updates are mandatory, in which case check for update -> if update found, start loading animation "updating" while you can detect that the launcher is still running. Ensure that the launcher has no race condition while loops!
I found ready project to solve automatically updating.
You can update your app, in your cases you can update jars and resources of your desktop app. The idea of the this is next: wrap you app with starter which can control updating and running you app. In details you can find here.
I'm trying to use this tool
https://swingexplorer.dev.java.net/
to find some information out about an applet's swing structure. Unfortunately, I didn't develop the applet. I've pulled the jars for the applet from the cache, but there are several hundred .class files in the jars, and I don't know which one has the main method.
Is there a way to pinpoint the applet's entry point? The browser must be able to figure it out to run the applet, so that information has to be somewhere in the jar (or maybe the .idx files that were in the same directory with the jars).
Ideas appreciated.
The lifecycle of an Applet (or JApplet) is more complicated than start and run until the program is finished so there is no single main method. It will be managed by the browser (lifecycle tutorial.)
The applet class is specified by the deployment mechanism (e.g. applet/object/embed tags.) See the deployment tutorial for determining how this type is specified.
The entry class will either be in the applet tag, or JNLP for new plugin JRE 6u10+ applets. You should be able to see which one it is from the jar alone by grepping for referecnes to the Applet or JApplet classes or, say, the init()V method.
I was trying to use the wrong tool for the task.