Free jrebel alternative download#
Continue coding and see the changes in your app immediately 😉įirst, download the DCEVM installer for your Java installation. The project is pretty quick to release new versions for new Java updates.Start the application in debug mode and connect to it via the debugger interface from withing IDE.Configure the IDE to refresh plain text resources like XML, property files, in the running application (this has to be done by the IDE because it’s not supported by Java debugger).Configure the IDE to start the application with the HotswapAgent JAR as java agent and using the DCEVM engine instead of the standard JVM engine.
Free jrebel alternative install#
Install the DCEVM engine into a Java installation (JRE or JDK).
So to summarize, we are going to do this to work with HotSwap from our IDE of choice:
Free jrebel alternative code#
The alternative VM engine is basically a patched version of the standard engine, which improves code hot swap via the debugging interface, without impacting other functions of the JVM. However, getting the most of Hotswap Agent requires installing an alternative DCEVM engine into your JRE installation, which does much better job in reloading code changes than the standard VM engine in the HotSpot VM. It’s also possible to write custom plugins for any project or even specifically for your application. It essentially scans the classpath to detect the presence of known frameworks and tries to refresh the frameworks after a code or resource change is detected. Hotswap Agent itself is just a java agent, which has to be attached to the application. I’m going to write up how I got it running in my IDE and my Java EE server of choice – Payara Server. I tried HotswapAgent and it has worked very well as a free alternative of JRebel for me for my personal Java EE projects. I have some experience with JRebel and I liked it a lot, but I was using it on a commercial project where I didn’t pay for the license. But the downside is that it’s pretty expensive for a casual developer, doing just some hacking on his/her own or working on a non-commercial project. There’s been a lot of effort put into it to support all sorts of code and resource changes and refresh them with virtually any Java framework used by the application. Many developers know that JRebel can help a lot with updating the code on the fly. A while ago I’ve come across an opensource tool called HotswapAgent that speeds up code reloading. And all developers know that restoring the desired state of the application after a fresh restart takes time and is tedious. With Java, it’s always necessary to rebuild the source code in a bytecode, which can be then safely updated only by restarting the whole application.
As a Java EE developer, I sometimes envy how fast it’s possible to see the result of a code change in a running application with interpreted languages like PHP or JavaScript.
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