عرض عملي: بناء @Timed مصغّر باستخدام وكيل

خطوة بخطوة

1. Define @Timed (RUNTIME, METHOD) and an interface PriceService with an implementation.
2. Write a Proxy.newProxyInstance handler that checks the annotation on the target method and logs elapsed time.
3. Call through the proxy; see the timing log.
4. Planned mistake: annotate only the interface method and read the annotation from the implementation class (not found). Fix: look up the annotation on the target class method (and note Spring's own lookup rules).
5. Add an internal call between two methods; show it is not timed (self-invocation).
6. Discuss reflection cost and caching Method lookups.