I have a Java jar file that I run from a Windows command prompt: java jar-file class args…. I would like to use it in a web app, where it would run on the client side; more or less as an applet rather than a servlet. Is there an easy way to do this? Short of decompiling, I don't have access to the Java source code, but I would be willing to add additional classes to the jar file. One other complication: the arguments to the jar command include the names of an input and output file. I'm pretty sure I can replace them with i/o stream objects but a solution would need to translate data urls.
Is there an easy way to do this?
No. You might write a (trusted) applet wrapper that redirects the system out and in streams to use them in the applet, but applets are never easy.
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I am quite new to working with jars and from reading online I think what I am describing is possible but I am not sure about it. If anyone has an alternative pipeline, I welcome that as well. Thanks for your time.
I would like to do the following:
I have a java program running on my machine and I would like to accept requests jars during runtime from a remote user. The users submits the jar and I would like to add the classes in the jar (which implement some predefined interfaces) to my classpath and call functions that are implemented in the submitted jar. I am using thrift as my communication platform.
How can I receive the jar file in thrift?
Once I have the jar, how do I load it? (There is no path etc because it was received from elsewhere?)
I want to make a Chrome plugin that checks if mencoder.exe is present on the clients system. And if so, convert files with it.
Is that possible?
If not, can I make something like that in a Java applet or something? I'm open to suggestions!
It is possible with java applets, but you also need to implement a permission policy into the program. Here are two tutorials you should take a look at:
Java applets:
http://docs.oracle.com/javase/tutorial/deployment/applet/
Implementing Policy:
http://docs.oracle.com/javase/tutorial/security/userperm/policy.html
You can do it using java applet (like Laerte said), but implementing a policy is not the only option. May be it is easier digital signing (info) your applet with respective attributes in Manifest.mf (here and here) and wrapping your SO access source lines with this. In this way, you can distribute your applet without modifying client systems.
I have a java application(runnable jar) and VB scripts which I'm using to telnet to a remote machine and executing some cmds. So, I first execute the vbs files and then run my jar(in all everything is working fine).
But, now I want to integrate scripts and my java jar such that, running the jar should first trigger the script followed by Java related task.
Few thing which I've come across are -
I cannot trigger Vbs from Java(javax.script - correct me if I'm wrong). So, possible options to rewite the script in are -
Javascript(have no idea what my Javascript file would have so that after reading it inside java class I can write it to the Socket output stream.)
PHP(I tried this using Java bridge but it gives some error saying cgi needs to installed. And, I believe it also requires PHP to be installed on the host machine before executing my jar. So I'm not going any futher with this approach.)
Long story short, I don't want to create any dependencies - I am looking for something like where I can package any external lib with my jar(if required) and use it to execute my scripts.
You can execute the VB-Script in an external command. There are a lot of resources on the internet that explain how to do that - for instance this link also explains how to start a VB-Script from within java. However I do not know if you need the output from the script within the Java. If so you'll have to listen to the outputstream of the created process. You should find an example for that as well with that link (using the processbuilder)
If you have the script packaged within your jar, I fear you'll have to unpack it to a temporary folder and execute it there.
The closest I have seen about VB script as a JVM language is in answer here.
Visual Basic or VBScript as Java Scripting Engine
Have you seen this wikipedia entry about JVM languages?
http://en.wikipedia.org/wiki/List_of_JVM_languages
Also, have you considered using Ant and using it programmatically from java?
Another option is to use groovy/Ant from Java.
I just got a requirement to create a small (I assume standalone) utility to hit some code in our web application to do some custom processing of files from the app and then dump the files into a shared drive. My question is what is the best way for doing this? Do I just create a small app and then jar it up and run it off a command line or is there a better way?
Sorry, I didn't give enough detail. It's an old application, like over 10 years, so while it's been upgraded to jdk 1.6, most of the code uses the old collections, old loops, etc... There aren't any interfaces, very tightly coupled code that uses inheritance with lots of nested objects. The web app will do the processing. I think what they want is create some code outside of the application code that will login and then fire off the file processing code. Prior to this I had upgraded their version of Windward Reports in a separate branch and they want to make sure that the processed files: contracts, forms, etc.. don't get altered greatly as there are legal requirements on fonts and layouts. So this utility will go in, fire off the list of reports (a few thousand) dump it to a share drive so they can view them with another tool for comparision based on rules you can automate with that commercial tool, en masse. I was thinking create a small class with a main method, then jar it up and while the web server is running with my upgraded branch code, run the utility off the command line to fire it off.
There's not enough to go on here. How is the web app's functions exposed? If it's a REST interface then wget/curl/spring-rest-template are the way to go. If it's something like a JFS app then you're going to need something like Selenium to imitate a browser. If the functionality is in a shared library (JAR) then there web never even comes into play.
Well, I was originally looking at creating a standalone utility jar that I would run off the command line to connect with URLConnection to the app, but I found there is already testing code built into the application that I can run from a command line as long as I deploy the new code with the existing code. The utility will dump out the files to a shared drive and then XTest can be run to compare files. After reviewing the capabilities of XTest, it appears that it can handle the comparison of files well.
I am trying to create executable under windows platform for Java program using JNI ,C/C++ and invocation API, I have already created jar file for my program which includes all dependencies. I want to embed it in exe file, I was successful in running simple main class(present in file system) using JNI invocation API, I am planning to add jar file as resource in C/C++ program. But I don't know how do I run that jar file , One option is create temporary jar file on file system and run it using java, But I do not want to expose my jar file to everyone for security reasons, How can I run jar file on the fly using JNI ?
Compiling Java to an executable with GCJ does not work all the time, there are limitations as far as using reflection and other items such as UI classes, Look at this page.
If you convert you Java Code to a library or simply another module then you could link to it and simply run it without the need for a JVM.
My initial reaction was that I would be shocked if you could get this to work and have it be performant. But then I started thinking about it, and maybe you could pull this off using a custom class loader. If you embed the jar in the exe as a resource, it would be exactly the same as having the jar bytes be present at a particular offset in any file (whether an exe or not).
So, here's a potential strategy: implement a custom class loader that accepts the exe path and offset of the jar resource in that file. This would use a custom version of ZipFile that uses a fixed index offset for it's reads (unfortunately, it isn't going to be possible to use ZipFile itself - but if you grab the source of ZipFile it should be pretty obvious where you'll need to add the offset).
There is a bootstrapping issue here (how do you load the custom class loader?) - but I think it might be possible to do that from the JNI side. Basically you'd store the .class file for the loader as a separate resource in the exe, load it fully into memory then construct it using JNI calls. That will be a hassle, but it's just for one class, and then you can let the Java runtime take over the rest.
Sounds like an interesting project (Although, as others are pointing out, there isn't much security in what you are doing... I suppose that you could encrypt the embedded jar and add decryption code to the classloader, but you've kinda got to decide how far you want to take this thing).