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asmTransformClasses

README.md

Use the Instrumentation.transformClassesWith() API to transform classes with ASM

This sample shows how to use the Instrumentation.transformClassesWith() API to transform classes using an ASM class visitor.

This recipe contains the following directories:

Module Content
build-logic Contains the Project plugin that is the core of the recipe.
app An Android application that has the plugin applied.

The build-logic sub-project contains the CustomPlugin, ExampleClassVisitorFactory, ClassMethodVisitor and CheckAsmTransformationTask classes.

CustomPlugin contains the code which calls the transformClassesWith() API on the classes. In this method, the class visitor which performs the transformation is specified, as well as the instrumentation scope and the instrumentation parameter initialization. The ExampleClassVisitorFactory is used as the class visitor factory, which transforms the classes using the ClassMethodVisitor. It contains ExampleParams as well, which are the parameters specified in the API call and used in the factory. An example usage is:

variant.instrumentation.transformClassesWith(
    ExampleClassVisitorFactory::class.java,
    InstrumentationScope.PROJECT
) { params ->
    params.newMethodName.set("transformedMethod")
}

Here, the newMethodName property is a parameter specified in ExampleParams. Lastly, the CheckAsmTransformationTask is included in this sample, which validates the transformation. Because this task creates a dependency on the classes, calling it runs the necessary tasks to gather the classes artifact, transform it, and validate the transformation.

To Run

To execute example you need to enter command:

./gradlew :app:checkDebugAsmTransformation