Spring GAE Java 8 Objenesis

Objenesis went out last week partly because Google App Engine is now supporting Java 8 in beta. And they are no security manager anymore preventing Objenesis to work.

The problem was that Objenesis was checking if it was running on GAE to pick an instantiating strategy. So it was still running in degraded more on GAE Java 8. It is now fixed.

However, Spring uses an embedded version of Objenesis. So they need to upgrade. Luckily, they are super fast to do so. You can follow the issue but it will be in Spring 4.3.10 and Spring Boot 1.5.5.

Meanwhile, you might be eager to test your shiny new app on this new Google App Engine platform and would be really happy to make it work.

I have a solution for you. It isn’t pretty but it works.

In Java, in case you don’t know, you just need to put your class file in front of another one in the classpath to “shadow” it. It means your class will be used instead of the original implementation. In a war, everything in WEB-INF/classes goes before WEB-INF/lib. So you can easily shadow a class.

That’s what I did. My SpringObjenesis.java version shadows Spring one. It delegates to the real Objenesis implementation instead of the Spring embedded one. You only need to add the latest Objenesis (2.6) as a dependency to your project.