springAOP : spring AOP with Annotations

Spring AspectJ AOP implementation provides many annotations:

@Aspect declares the class as aspect.

@Pointcut declares the pointcut expression.

The annotations used to create advices are given below:

@Before declares the before advice. It is applied before calling the actual method.

@After declares the after advice. It is applied after calling the actual method and before returning result.

@AfterReturning declares the after returning advice. It is applied after calling the actual method and before returning result. But you can get the result value in the advice.

@Around declares the around advice. It is applied before and after calling the actual method.

@AfterThrowing declares the throws advice. It is applied if actual method throws exception.

Understanding Pointcut

Pointcut is an expression language of Spring AOP.

The @Pointcut annotation is used to define the pointcut. We can refer the pointcut expression by name also. Let's see the simple example of pointcut expression.

@Pointcut("execution(* Employee.*(..))") 

private void doSomething() {} 

The name of the pointcut expression is doSomething(). It will be applied on all the methods of Employee class regardless of return type.

Understanding Pointcut Expressions

Let's try the understand the pointcut expressions by the examples given below:

@Pointcut("execution(public * *(..))") 

It will be applied on all the public methods.

@Pointcut("execution(public Employee.*(..))") 

It will be applied on all the public methods of Employee class.

@Pointcut("execution(* Employee.*(..))") 

It will be applied on all the methods of Employee class.

@Pointcut("execution(public Employee.set*(..))") 

It will be applied on all the public setter methods of Employee class.

@Pointcut("execution(int Employee.*(..))") 

It will be applied on all the methods of Employee class that returns int value.