Java 11-Kotlin批注处理器

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.SOURCE)
public @interface GenerateCode {
}

import javax.annotation.processing.AbstractProcessor;
import javax.annotation.processing.RoundEnvironment;
import javax.annotation.processing.SupportedAnnotationTypes;
import javax.annotation.processing.SupportedSourceVersion;
import javax.lang.model.SourceVersion;
import javax.lang.model.element.Element;
import javax.lang.model.element.TypeElement;
import java.io.IOException;
import java.io.Writer;
import java.util.Set;

@SupportedAnnotationTypes("com.example.GenerateCode")
@SupportedSourceVersion(SourceVersion.RELEASE_8)
public class CodeGeneratorProcessor extends AbstractProcessor {
    @Override
    public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
        for (Element element : roundEnv.getElementsAnnotatedWith(GenerateCode.class)) {
            if (element instanceof TypeElement) {
                String className = ((TypeElement) element).getQualifiedName().toString();
                try (Writer writer = processingEnv.getFiler().createSourceFile(className + "Generated").openWriter()) {
                    writer.write("public class " + className + "Generated {\n");
                    writer.write("    public void printClassName() {\n");
                    writer.write("        System.out.println(\"" + className + "\");\n");
                    writer.write("    }\n");
                    writer.write("}\n");
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return true;
    }
}

@GenerateCode
public class MyClass {
    public void myMethod() {
        // ...
    }
}

public class MyClassGenerated {
    public void printClassName() {
        System.out.println("com.example.MyClass");
    }
}