mumrah/guice-jcl

Example project using JCL with Guice injection

Example of using Guice with JCL

This is a sample project to demonstrate how to use Google Guice dependency injection with JCL (JarClassLoader).

How it works

Instead of using JCL's JclObjectFactory to instantiate objects, you bind the Classes returned by JCL in a Guice module. Here is a simple example binding SomeImpl to SomeInterface. The impl class resides in "some.jar" which is loaded at runtime by JCL.

JarClassLoader jcl = new JarClassLoader();
jcl.add("some.jar");
Class<SomeInterface> clazz = (Class<SomeInterface>)jcl.loadClass("SomeImpl");
Injector injector = Guice.createInjector(new AbstractModule() {
    @Override
    protected void configure() {
      bind(SomeInterface.class).to(clazz);
    }
});

SomeInterface something = injector.getInstance(SomeInterface.class); // This returns SomeImpl

What's in this repo

Two plugins (plugin-a and plugin-b) which both depend on different versions of Jackson. JCL loads the plugins from a "plugins" directory at runtime and binds them to a Guice Multibinder. A dependent class then gets injected with both plugins and runs them.

To run the example: ./gradlew :main:run