CODEWITHSUNDEEP
javagradlereflectiongradle-plugin
user3489006
user3489006

Reputation:

Load classpath of project gradle plugin is applied to

I am writing a custom gradle plugin, which will generate some code for me, based on the code it finds in the project it is applied to. For this I need to find all classes that extend a specific class. The problem is that the class, that is extended, is not loaded in the classpath, since it is a dependency of the other project.

Currently I got this for my custom Task

public class GenerateCodeTask extends DefaultTask {

    @TaskAction
    public void generateCode() throws MalformedURLException, ClassNotFoundException {
        File buildDir = new File(getProject().getBuildDir(), "classes/main");
        File root = new File(getProject().getProjectDir(), "src/main/generated");

        URLClassLoader classLoader = new URLClassLoader(new URL[]{buildDir.toURL()});
        Class itemClass = classLoader.loadClass("net.minecraft.item.Item");
        Reflections reflections = new Reflections(classLoader);
        Set<Class<?>> items = reflections.getSubTypesOf(itemClass);
    }
}

And this for the plugin

public class EasymodsPlugin implements Plugin<Project> {
    @Override
    public void apply(Project p) {
        Task t = p.getTasks().create("generateCode", GenerateCodeTask.class);

        t.dependsOn(p.getTasks().getByPath("compileJava"));
    }
}

This is the error I am getting

java.lang.ClassNotFoundException: net.minecraft.item.Item

I know that the problem is that the library containing the class is not loaded, and that causes the exception. What I want is to be able to load all dependencies of my project into the classloader, so I can use reflections to find all "items" in the project (which I need to generate code)

Greetings Failender

Upvotes: 0

Views: 2390

Answers (1)

trompa
trompa

Reputation: 2007

I think you almost got it.

You need the compileClasspath property. I pass it as an input parameter to my task, and build the Class Loader from it:

In plugin:

Set<File> ccp = project.getConfigurations().getByName("compileClasspath").getFiles();
task.classpath = ccp;

In task:

@InputFiles
Iterable<File> classpath;

What this property is adding is:

  1. the path to the classes on projects it depends on that are generated under project_id/build dir. ( So no need to build the path manually )
  2. All library deps for your project. That i think you were missing.

So, in the case your class is of type 1:

It is better if you have different subprojects: the one that has the original classes and the other with the generated ones.

So the second depends on the first:

dependencies {
    compile project(':my_project_with_classes_to_extend')
}

In the case is the second one, you can just add the library as a dep to your project and it will find the class.

And rewire the tasks so you are sure the fist project is built before calling your task (just on root level of your 2nd project build.gradle):

I think that´s the part that wasn't really working for you, apparently, compileJava and build are not exactly the same. Or at least, compileJava wasnt working for me either.

myGeneratorTask.dependsOn( ":my_project_with_classes_to_extend:build" )
compileJava.dependsOn( "myGeneratorTask" )

Upvotes: 2

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