If there is a class com.app.A from JAR-1 loaded into the JVM then how can we load a new version of the same class com.app.A from another JAR-2 at runtime?
What are the different ways to do this?
- Abhijit
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2 Answers
One way is OSGi. You can have multiple versions of the same bundle (jar) in an OSGi environment.
Say we have JAR-1 and JAR-2 in OSGi runtime exposing the same packages but different versions like this.
JAR-1 exports > org.home.code;version=1.0.0
JAR-2 exports > org.home.code;version=2.0.0
Now when some other jar needs org.home.code as a dependency, it can specify which version it needs.
You can find some popular OSGi implementations here.
Comments
You have two options:
First: You can do it like it described here:
Java ClassLoader: load same class twice
Second: You can just manually try to replace old *.class to new one. You can catch plenty of exceptions if you made significant changes, like added methods etc. I changed some logging, made some internal method refactoring and it worked for me.
