Transform

1. //com.android.build.gradle.internal.dsl.BaseAppModuleExtension_Decorated实例
def android = project.extensions.getByType(AppExtension)
或
AppPlugin appPlugin = getProject().getPlugins().getPlugin(AppPlugin.class)
//com.android.build.gradle.internal.dsl.BaseAppModuleExtension_Decorated实例
def android = appPlugin.getExtension()
    
2. android.registerTransform(new MyClassTransform(project));

graph LR
registerTransform-->addTransform("BaseExtension.transforms.add(transform);")-->|TaskManager.createPostCompilationTasks|transformManager.addTransform-->TransformTask.transform

public abstract class BaseExtension implements AndroidConfig {
public void registerTransform(@NonNull Transform transform, Object... dependencies) {
        transforms.add(transform);
        transformDependencies.add(Arrays.asList(dependencies));
}
@Override
@NonNull
public List<Transform> getTransforms() {
    return ImmutableList.copyOf(transforms);
}

public abstract class TaskManager {
public void createPostCompilationTasks(
        @NonNull final VariantScope variantScope) {
        
         // ----- External Transforms -----
        // apply all the external transforms.
        List<Transform> customTransforms = extension.getTransforms();
        List<List<Object>> customTransformsDependencies = extension.getTransformsDependencies();

        for (int i = 0, count = customTransforms.size(); i < count; i++) {
            Transform transform = customTransforms.get(i);

            List<Object> deps = customTransformsDependencies.get(i);
            transformManager.addTransform(

public abstract class TransformTask extends StreamBasedTask {
    @TaskAction
    void transform(final IncrementalTaskInputs incrementalTaskInputs)
            throws IOException, TransformException, InterruptedException {
                                    transform.transform(
                                new TransformInvocationBuilder(context)
                                        .addInputs(consumedInputs.getValue())
                                        ....
                                        .build());

//TransformTask
@TaskAction
void transform(final IncrementalTaskInputs incrementalTaskInputs)
        throws IOException, TransformException, InterruptedException {

public interface TransformInput {
    Collection<JarInput> getJarInputs();
    Collection<DirectoryInput> getDirectoryInputs();
}

private void doTransform(TransformInvocation transformInvocation) throws ExecutionException, InterruptedException {
     Collection<TransformInput> inputs = transformInvocation.getInputs();
       for (TransformInput input : inputs) {
            for (DirectoryInput directoryInput : input.getDirectoryInputs()) {
            }

            for (JarInput inputJar : input.getJarInputs()) {
            }
        }