Annotated: Compositional and Named Pointcuts

Just as when defining pointcuts in XML, you can use named pointcuts when defining the AOP bindings using annotations.

Examples

Let's take a look at MyAspect.java

      import org.jboss.aop.Bind;
      import org.jboss.aop.Aspect;
      import org.jboss.aop.PointcutDef;
      import org.jboss.aop.pointcut.Pointcut;
      import org.jboss.aop.pointcut.Pointcut;

      @Aspect (scope=Scope.PER_VM)
      public class MyAspect
      {
         @PointcutDef("execution(POJO->new(..))")
         public static Pointcut pojoConstructors;

         @PointcutDef("get(* POJO->*)")
         public static Pointcut pojoFieldReads;

         @PointcutDef("set(* POJO->*)")
         public static Pointcut pojoFieldWrites;

         @PointcutDef("execution(* POJO->*(..))")
         public static Pointcut pojoMethods;

The @PointcutDef annotations create a named pointcut, so we get:

one matching exexutions of all constructors on the POJO class.
one matching exexutions of all methods on the POJO class.
one matching the reads of all fields in the POJ0 class
one matching the writes of all fields in the POJ0 class

The name of the annotated field becomes the name of the annotated field and is used when you reference the field. Note that for clarity we use org.jboss.aop.pointcut.Pointcut as the type of our field, but any type can be used.

Below we use composition to create a pointcut by referencing the two named pointcuts. As mentioned we reference them by the fully qualified names of the fields annotated with @PointcutDef

         @PointcutDef("MyAspect.pojoFieldReads OR MyAspect.pojoFieldWrites")
         public static Pointcut pojoFields;

         @Bind(pointcut = "MyAspect.pojoFields OR MyAspect.pojoMethods OR MyAspect.pojoConstructors")

         public Object anotherPOJOAdvice(Invocation invocation) throws Throwable
         {
            ...
         }

      }//End - class MyAspect

Running the example

Running the example you'll see composition in action

To compile and run:

  $ ant

It will javac the files and then run the AOPC precompiler to manipulate the bytecode, then finally run the example. The output should read as follows:

run:
     [java] --- pojo constructor ---
     [java] <<< MyAspect.anotherPOJOAdvice - calling constructor
     [java] constructor
     [java] >>> Leaving MyAspect.anotherPOJOAdvice
     [java] --- pojo.method(); ---
     [java] <<< MyAspect.anotherPOJOAdvice - calling method
     [java] method()
     [java] >>> Leaving MyAspect.anotherPOJOAdvice
     [java] --- pojo field write ---
     [java] <<< MyAspect.anotherPOJOAdvice - writing field
     [java] >>> Leaving MyAspect.anotherPOJOAdvice
     [java] --- pojo field read ---
     [java] <<< MyAspect.anotherPOJOAdvice - reading field
     [java] >>> Leaving MyAspect.anotherPOJOAdvice