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Some Concepts about Spring Framework

Advice:
Advice specifies what to do at a joint point. In the case of Spring, this is the additional behavior that Spring will inject around a method invocation. It is most often defined in a method interceptor, which will be invoked as part of  an interceptor chain wrapping the method invocation.

Advice Type:
Before Advice, as its name implies, executes before the joint point
After Returning Advice: is inoked when a method returns successfully, without throw an exception
Throws Advice:

The following advice is invoked if a ServletException or a RemoteException is thrown. This class implements an afterThrowing() method taking all four arguments, so it has access to the invoked method, method arguments, and target object:

public static class ServletThrowsAdviceWithArguments implements ThrowsAdvice {
 
    public void afterThrowing(Method m, Object[] args, Object target,
ServletException ex) {
        // Do something with all arguments
    }
 
    public void afterThrowing(RemoteException ex) throws Throwable {
        // Do something with remote exception
    }
}


Pointcuts:
Pointcuts identify where advice should apply.

Spring Pointcut Concepts:
Spring pointcuts are essentially ways of identifying method invocations that fit a certain criteria.

Advisors: In order to pull pointcuts and advice together, we need an object that contains both: that is, containing the behavior that should be added(advice) and where that behavior should apply(pointcut). Spring introduces the concept of an Advisor. an object that includes both advice and a pointcut speciying where that advice should apply. Unlike advice and pointcut, an advisor is not an established AOP concept, but a Spring-specific term.

The purpose of an Advisor is to allow both advice and pointcuts to be reusable independently.

Introduction: means an advised object implement additional interfaces, which are not implemented by the target object.

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