All Superinterfaces:: Advice

All Known Subinterfaces:: ConstructorInterceptor, FieldInterceptor, MethodInterceptor

public interface Interceptor extends Advice

This interface represents a generic interceptor.

A generic interceptor can intercept runtime events that occur within a base program. Those events are materialized by (reified in) joinpoints. Runtime joinpoints can be invocations, field access, exceptions...

This interface is not used directly. Use the the sub-interfaces to intercept specific events. For instance, the following class implements some specific interceptors in order to implement a debugger:

class DebuggingInterceptor implements MethodInterceptor, 
    ConstructorInterceptor, FieldInterceptor {

  Object invoke(MethodInvocation i) throws Throwable {
    debug(i.getMethod(), i.getThis(), i.getArgs());
    return i.proceed();
  }

  Object construct(ConstructorInvocation i) throws Throwable {
    debug(i.getConstructor(), i.getThis(), i.getArgs());
    return i.proceed();
  }

  Object get(FieldAccess fa) throws Throwable {
    debug(fa.getField(), fa.getThis(), null);
    return fa.proceed();
  }

  Object set(FieldAccess fa) throws Throwable {
    debug(fa.getField(), fa.getThis(), fa.getValueToSet());
    return fa.proceed();
  }

  void debug(AccessibleObject ao, Object this, Object value) {
    ...
  }
}

See Also:

Interface Interceptor