[FIXED] within is not necessary,spring aop.execution(* concert.Performance.perform(..)) && within(concert.*)

Issue

In the book "spring in action",there is an aspectj expresssion:

execution(* concert.Performance.perform(..)) && within(concert.*)

execution() Matches join points that are method execution.
You use the execution() designator to select Performance’s perform() method.

execution(* concert.Performance.perform(..))

within() Limits matching to join points within certain type.
you want to confine the reach of that pointcut to only the concert package.

within(concert.*)

But I think,left part and right part of the expression both matches join points,"* concert.Performance.perform(..)" indicates join points must be in one class "Performance",it is already in package "concert",so what is the use of "within(concert.*)"?
If it is an "or",maybe useful,but it is an "and".

Solution

in this case within(concert.*) is important and result will not be the same as just with execution(* concert.Performance.perform(..))

execution it's matching for methods.

within it's matching for types.

in this example you already has poincut execution -- for any parameter for method perform with any access modifier and you add 'specific type' - within(concert.*)

so your poincut it's --

execution(* concert.Performance.perform(..)) && within(concert.*)

for any return type , for method perform from class Performance from package concert that consume any type from package and sub - package concert

in case if you have just execution(* concert.Performance.perform(..)) it almost the same as for previous except that type can by ANY

Answered By - xyz
Answer Checked By - Mary Flores (JavaFixing Volunteer)