Custom Java Based Gradle Plugin and Classpath of Consuming Projects

Question

I have made a plugin with a task that will search the classpath for classes annotated with a specific annotation, using the Reflections library from google (here). However, when consuming the plugin and running the task, the current modules' classpath is not used. How can I get the task to look at the output from the jar task (from the java plugin) as on the classpath?

Here is my example plugin:

package com.myplugin;

import org.gradle.api.Plugin;
import org.gradle.api.Project;

public class MyPlugin implements Plugin<Project> {
    @Override
    public void apply(Project project) {
        project.getTasks().create("myplugintask", MyPluginTask.class);
    }
}

My Task Code:

package com.myplugin;

import lombok.Data;
import org.gradle.api.DefaultTask;
import org.gradle.api.tasks.TaskAction;
import org.reflections.Reflections;

public class MyPluginTask extends DefaultTask {
    @TaskAction
    public void reflect() {
        Reflections reflections = new Reflections("com.consumer.reflected");

        for (Class<?> clazz : reflections.getTypesAnnotatedWith(Data.class)) {
            getLogger().info(clazz.toString());
        }
    }
}

And my consuming project has a class:

package com.consumer.reflected;

import lombok.Data;

@Data
public class SomeClass {
}

I would expect to be able to run:

gradle myplugintask

And see the SomeClass, but reflections returns zero results.

Note: I have tried implementating an instantiation of the plugin (and task) inside of the consumer project, and ran it as a standard jar, and that succeeds (output shows SomeClass)

Answer 1

In a nutshell, the task class needs an @InputFiles Iterable<File> classpath property, the plugin needs to configure this property (e.g. myTask.classpath = project.sourceSets.main.compileClasspath), and the task action needs to somehow pass the class path to the reflections library. I'm sure you can work out the rest.