LogCall.java

@Retention(RetentionPolicy.RUNTIME)
public @interface LogCall {
}

LogCallDecorator.java

@CodeDecorator
public class LogCallDecorator extends IOCDecoratorExtension<LogCall> {
  public LogCallDecorator(Class<LogCall> decoratesWith) {
    super(decoratesWith);
  }

  @Override
  public List<? extends Statement> generateDecorator(InjectableInstance<LogCall> ctx) {
    ctx.getInjector().addInvokeBefore(ctx.getMethod(),
        Stmt.invokeStatic(TestDataCollector.class, "beforeInvoke", Refs.get("a0"), Refs.get("a1")));

    ctx.getInjector().addInvokeAfter(ctx.getMethod(),
        Stmt.invokeStatic(TestDataCollector.class, "afterInvoke", Refs.get("a0"), Refs.get("a1")));

    return Collections.emptyList();
  }
}

MyDecoratedBean.java

@Singleton
public class MyDecoratedBean {
  private final Map<String, Integer> testMap = new HashMap<String, Integer>();

  @LogCall
  public void someMethod(final String text, final Integer blah) {
    testMap.put(text, blah);
  }

  public Map<String, Integer> getTestMap() {
    return testMap;
  }
}

TestDataCollector.java

public class TestDataCollector {
  private static final Map<String, Integer> beforeInvoke = new HashMap<String, Integer>();
  private static final Map<String, Integer> afterInvoke = new HashMap<String, Integer>();

  public static void beforeInvoke(String a, Integer b) {
    beforeInvoke.put(a, b);
  }

  public static void afterInvoke(String a, Integer b) {
    afterInvoke.put(a, b);
  }

  public static Map<String, Integer> getBeforeInvoke() {
    return beforeInvoke;
  }

  public static Map<String, Integer> getAfterInvoke() {
    return afterInvoke;
  }
}