Programación Orientada a Aspectos: Interceptando LLamadas Utilizando Metaclases

La mayor diferencia de este código con el anterior es que la casle SimplePOGO no implementa GroovyInterceptable y no dispone de un método invokeMethod().

generaciondecodigos@nereida:~/Lgroovy/objects$ cat -n AOP2.groovy
 1  class SimplePOGO {
 2      void simpleMethod1(){
 3          System.out.println("simpleMethod1() called")
 4      }
 5
 6      void simpleMethod2(String param1, Integer param2){
 7          System.out.println("simpleMethod2(${param1},${param2}) called")
 8          System.out.println("sleeping...")
 9          Timer.sleep(2000)
10      }
11
12  }
13
14  SimplePOGO.metaClass.invokeMethod = { String name, args ->
15      System.out.println("time before ${name} called: ${new Date()}")
16
17      //Get the method that was originally called.
18      def calledMethod = SimplePOGO.metaClass.getMetaMethod(name, args)
19
20      calledMethod?.invoke(delegate, args)
21
22      System.out.println("time after ${name} called: ${new Date()}\n")
23  }
24
25  simplePogo = new SimplePOGO()
26  simplePogo.simpleMethod1()
27  simplePogo.simpleMethod2("stringParam", 24)
28  simplePogo.simpleMethod3(1, 2, 4)

En la llamada

calledMethod?.invoke(delegate, args)

debemos referirnos a delegate ya que this hace alusión al objeto clausura. Dentro de la clausura delegate se refiere al objeto cuyos métodos estan siendo interceptados.

generaciondecodigos@nereida:~/Lgroovy/objects$ groovy AOP2.groovy
time before simpleMethod1 called: Tue Feb 23 16:47:40 WET 2010
simpleMethod1() called
time after simpleMethod1 called: Tue Feb 23 16:47:40 WET 2010

time before simpleMethod2 called: Tue Feb 23 16:47:40 WET 2010
simpleMethod2(stringParam,24) called
sleeping...
time after simpleMethod2 called: Tue Feb 23 16:47:42 WET 2010

time before simpleMethod3 called: Tue Feb 23 16:47:42 WET 2010
time after simpleMethod3 called: Tue Feb 23 16:47:42 WET 2010