@SupportedAnnotationTypes({"moscow.droidcon2015.processor.BindView"})
public class DroidConProcessor extends AbstractProcessor {

    private final Map<TypeElement, BindViewVisitor> mVisitors = new HashMap<>();

    @Override
    public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
        if (annotations.isEmpty()) {
            return false;
        }

        final Set<? extends Element> elements = roundEnv.getElementsAnnotatedWith(BindView.class);
        for (final Element element : elements) { // element == MainActivity.mFab
            final TypeElement object = (TypeElement) element.getEnclosingElement(); // object == MainActivity
            BindViewVisitor visitor = mVisitors.get(object);
            if (visitor == null) {
                visitor = new BindViewVisitor(processingEnv, object);
                mVisitors.put(object, visitor);
            }
            element.accept(visitor, null);
        }

        for (final BindViewVisitor visitor : mVisitors.values()) {
            visitor.brewJava();
        }

        return true;
    }

    @Override
    public SourceVersion getSupportedSourceVersion() {
        return SourceVersion.latestSupported();
    }

}

public class BindViewVisitor extends ElementScanner7<Void, Void> {

    private final CodeBlock.Builder mFindViewById = CodeBlock.builder();

    private final Trees mTrees;

    private final Messager mLogger;

    private final Filer mFiler;

    private final TypeElement mOriginElement;

    private final TreeMaker mTreeMaker;

    private final Names mNames;

    public BindViewVisitor(ProcessingEnvironment env, TypeElement element) {
        super();
        mTrees = Trees.instance(env);
        mLogger = env.getMessager();
        mFiler = env.getFiler();
        mOriginElement = element;
        final JavacProcessingEnvironment javacEnv = (JavacProcessingEnvironment) env;
        mTreeMaker = TreeMaker.instance(javacEnv.getContext());
        mNames = Names.instance(javacEnv.getContext());
    }

}

    @Override
    public Void visitVariable(VariableElement field, Void aVoid) {
        ((JCTree) mTrees.getTree(field)).accept(new TreeTranslator() {
            @Override
            public void visitVarDef(JCTree.JCVariableDecl jcVariableDecl) {
                super.visitVarDef(jcVariableDecl);
                jcVariableDecl.mods.flags &= ~Flags.PRIVATE;
            }
        });
        final BindView bindView = field.getAnnotation(BindView.class);
        mFindViewById.addStatement("(($T) this).$L = ($T) findViewById($L)",
                ClassName.get(mOriginElement), field.getSimpleName(), ClassName.get(field.asType()), bindView.value());
        return super.visitVariable(field, aVoid);
    }

    public void brewJava() {
        final TypeSpec typeSpec = TypeSpec.classBuilder(mOriginElement.getSimpleName() + "$$Proxy") // MainActivity$$Proxy
                .addModifiers(Modifier.ABSTRACT)
                .superclass(ClassName.get(mOriginElement.getSuperclass())) // extends AppCompatActivity
                .addOriginatingElement(mOriginElement)
                .addMethod(MethodSpec.methodBuilder("setContentView")
                        .addAnnotation(Override.class)
                        .addModifiers(Modifier.PUBLIC)
                        .addParameter(TypeName.INT, "layoutResId")
                        .addStatement("super.setContentView(layoutResId)")
                        .addCode(mFindViewById.build()) // findViewById...
                        .build())
                .build();
        final JavaFile javaFile = JavaFile.builder(mOriginElement.getEnclosingElement().toString(), typeSpec)
                .addFileComment("Generated by DroidCon processor, do not modify")
                .build();
        try {
            final JavaFileObject sourceFile = mFiler.createSourceFile(
                    javaFile.packageName + "." + typeSpec.name, mOriginElement);
            try (final Writer writer = new BufferedWriter(sourceFile.openWriter())) {
                javaFile.writeTo(writer);
            }
            // TODO: MAGIC
        } catch (IOException e) {
            mLogger.printMessage(Diagnostic.Kind.ERROR, e.getMessage(), mOriginElement);
        }
    }

JCTree.JCExpression selector = mTreeMaker.Ident(mNames.fromString(javaFile.packageName));
selector = mTreeMaker.Select(selector, mNames.fromString(typeSpec.name));
((JCTree.JCClassDecl) mTrees.getTree(mOriginElement)).extending = selector;

// Generated by DroidCon processor, do not modify
package moscow.droidcon2015.activity;

import android.support.design.widget.FloatingActionButton;
import android.support.v7.app.AppCompatActivity;
import java.lang.Override;

abstract class MainActivity$$Proxy extends AppCompatActivity {
  @Override
  public void setContentView(int layoutResId) {
    super.setContentView(layoutResId);
    ((MainActivity) this).mFab = (FloatingActionButton) findViewById(2131492965);
  }
}

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//

package moscow.droidcon2015.activity;

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.view.View;
import android.view.View.OnClickListener;
import moscow.droidcon2015.activity.MainActivity$$Proxy;

public class MainActivity extends MainActivity$$Proxy {
    FloatingActionButton mFab;

    public MainActivity() {
    }

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        this.setContentView(2130968600);
        this.mFab.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
            }
        });
    }
}

@Override
public void visitMethodDef(JCTree.JCMethodDecl methodDecl) {
   super.visitMethodDef(methodDecl);
   methodDecl.body.stats = com.sun.tools.javac.util.List.<JCTree.JCStatement>of(
           mTreeMaker.Try(
                   mTreeMaker.Block(0, methodDecl.body.stats),
                   com.sun.tools.javac.util.List.<JCTree.JCCatch>nil(),
                   mTreeMaker.Block(0, com.sun.tools.javac.util.List.<JCTree.JCStatement>of(
                           mTreeMaker.Exec(mTreeMaker.Apply(
                                   com.sun.tools.javac.util.List.<JCTree.JCExpression>nil(),
                                   ident(mPackageName, mHelperClassName, "update"),
                                   com.sun.tools.javac.util.List.of(
                                           mTreeMaker.Literal(TypeTag.CLASS, mColumnName),
                                           mTreeMaker.Select(mTreeMaker.Ident(mNames._this), mNames.fromString(mFieldName)),
                                           mTreeMaker.Select(mTreeMaker.Ident(mNames._this), mNames.fromString(mPrimaryKey.call()))
                                   )
                           ))
                   ))
           )
   );
}

// было
public void setText(String text) {
   mText = text;
}

// стало
public void setText(String text) {
   try {
       this.mText = text;
   } finally {
       Foo$$SQLiteHelper.update("text", this.mText, this.mId);
   }
}