我需要log4j 1.2和2.5共存于同一webapp中

Question

I have a java webapp that uses Crystal's Business Objects runtime to run a report coded in that technology. The problem is that the monkeys at Crystal directly referenced a method in a log4j 1.2 class. This method isn't part of the log4j 1.2 to 2.5 bridge api. Nor should it be because Crystal shouldn't be calling it directly.

I have no choice but to use Crystal, our organization is locked in on it. I can only choose to either roll back the entire app to NOT use log4j2.5 like all of our other apps, OR I need to find a way they can coexist. When i put both jars in the classpath, the app tends to get confused as to what to load and we get no logging out. Remove that jar, and logging works great...but Crystal bombs.

I really don't want to roll everything back to 1.2. Is there a way to make them coexist nicely? Like make 1.2 higher on the classloader only when calling Crystal or something? Anyone know some trick that can help me here?

Answer 1

proxy-object proxy-object library

Put Crystal jar and all its dependencies in a folder (/path/to/crystalLib/)

Code Examples

Create any class from the Crystal library:

    File libDir = new File("/path/to/crystalLib/");

    ProxyCallerInterface caller = ObjectBuilder.builder()
            .setClassName("org.crystal.report")
            .setArtifact(DirArtifact.builder()
                    .withClazz(this.getClass())
                    .withVersionInfo(newVersionInfo(libDir))
                    .build())
            .build();
    String version = caller.call("crystalMethod").asString();

proxy-object library will handle separate class loader mess and you should be able to load any conflicting dependancies this way.