As we learned before, pointcuts define a point where advice should be applied. Spring AOP uses AspectJ's expression language to define a point where advice should be applied. The following are the set of pointcut designators supported in Spring AOP:
|
Designator |
Description |
| execution | It restricts matching to join points by a method execution. |
| within |
It restricts matching to join points within certain types only. Example: within(com.packt.springhighperformance.ch3.TransferService). |
| args |
It restricts matching to join points where arguments are of the given type. Example: args(account,..). |
| this |
It restricts matching to join points where the bean reference or Spring proxy object is an instance of the given type. Example: this(com.packt.springhighperformance.ch3.TransferService). |
| target |
It restricts matching to join points where the target object is an instance of the given type. Example: target(com.packt.springhighperformance.ch3.TransferService). |
| @within |
It restrict matching to join points where the declared type has the given type of annotation. Example: @within(org.springframework.transaction.annotation.Transactional). |
| @target |
It restricts matching to join points where the target object has the given type of annotation. Example: @target(org.springframework.transaction.annotation.Transactional). |
| @args |
It restricts matching to join points where the type of the actual arguments passed have annotations of the given type. Example: @args(com.packt.springhighperformance.ch3.Lockable). |
| @annotation |
It restricts matching to join points where the executing method has the given annotation. Example: @annotation(org.springframework.transaction.annotation.Transactional). |
Let's see how to write the point expression using the execution designator:
- Using execution(<method-pattern>): Method matching to the pattern would be advised. The following is the method pattern:
[Modifiers] ReturnType [ClassType]
MethodName ([Arguments]) [throws ExceptionType]
- To create composite pointcuts by joining other pointcuts, we can use the &&, ||, and ! operators (these mean AND, OR, and NOT, respectively).
In the preceding method pattern, anything defined in [ ] is optional. Values without [ ] are mandatory to define.
The following diagram will illustrate point expression using the execution designator to apply advice whenever the findAccountById() method is executed:
