Updating library for Jar/Programs

Question

I'm looking for an update library for the software I am developing. It's a small software, but I'd like to imbue it with some nice features. One of those is auto-update. I've developed 2 class library to do this job for me, but I'd like a more robust library, becuase it's missing some features. Between the features the library could have, these could be in it:

• Generate a difference file based on the old version (jar for example). Given the current version of the jar, and the new jar file, generate a new jar that will be downloaded by the clients, puting only the files that were changed since the last update.
• Check some kind of checksum. Each file inside the JAR have it's own checksum, or the whole jar having a checksum.
• Generate those checksum. If possible, while attending to the first item. File by file, or jar by jar, given the new files.
• It would be nice if it could deal also if the input is a folder or a jar.
• Merge the current jar with the downloaded one.

P.S.: I'm not writing a web-based (that runs in a browser) application.

Thanks for the attention.

Answer 1

There are many possible ways of doing that. In fact, you already pointed what you need. While developing such a solution isn't a big deal, there are also many libraries and products that already do that.

Some examples are already stated in similar questions, like:

Autoupdate Feature in a Java Swing Desktop App

or

Design of auto-updating software

One example, out of a simple google web search is Autoupdate+ One thing to remember is that the install/update software doesn't necessarily need to be written in Java itself...

Answer 2

Found the perfect solution for my needs in this answer: java web start alternative

Please take a look at this software https://code.google.com/p/getdown/ It claims it can be GCJ and be used to update also non-Java applications. But this does fills my expectations!