Defining an Aspect

In this lesson, we will define an aspect to intercept all the calls to the business layer and log their output. We will create a number of aspects and place all of them in a separate package.

When we intercept method calls, we have the option to perform tasks before the method is executed as well as afterwards. To define an aspect for a cross-cutting concern, we will perform the following steps:

• Define aspect class.
• Write methods containing the advice to be executed when method calls are intercepted.
• Write pointcut expressions for intercepting method calls.

Aspect

Suppose we want to intercept method calls to check if the user has access before the method gets executed. Access check is a cross-cutting concern and instead of implementing it in every method, we can write it as an aspect.

We will create a class called AccessCheckAspect and place it in the aspect package. To establish that this is a configuration class, we will use the @Configuration annotation. We will also add the @Aspect annotation to establish that this class is related to AOP.