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This article focuses on "how to use Spring AOP for testing". Interested friends may wish to have a look at it. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn how to test with Spring AOP.

AOP parsing

Today to introduce the concept of AOP,AOP, another core technology point of Spring, is difficult to understand. I hope you will read the article carefully and practice according to the code in the article. There will be great gains at that time!

AOP (Aspect OrientProgramming), literally translating means aspect-oriented programming. AOP is a programming idea and a supplement to object-oriented programming (OOP). Object-oriented programming abstracts the program into all levels of objects, while aspect-oriented programming abstracts the program into various aspects. Pick a picture from the book "Spring practice (4th Edition)":

From this diagram, we can see that the so-called section is equivalent to the crosscutting point between application objects, which can be abstracted as a separate module.

Spring provides rich support for aspect-oriented programming through dynamic proxies. Allows cohesive development by separating the application's business logic from system-level services such as auditing and transaction management. Application objects only do what they are supposed to do-- complete the business logic-- that's all. They are not responsible for (or even aware of) other system-level concerns, such as logging or transaction support.

The effect of AOP is to ensure that developers add some common functions to the business components in the system without modifying the source code.

The basic running process of AOP is shown in the following figure:

Feature terms in the AOP domain:

Crosscutting concern: a method or function that spans multiple modules of an application. That is, it has nothing to do with our business logic, but the part we need to focus on is crosscutting concerns. Such as logs, security, caching, transactions and so on.

ASPECT: special objects where crosscutting concerns are modularized. That is, it is a class.

Advice: enhanced processing in the AOP framework. The notification describes when the aspect is executed and how to perform the enhancement processing. It is a method in the class.

Target (Target): the notified object.

Proxy: the object created after the notification is applied to the target object.

JointPoint: indicates a point that can be inserted into a section during the execution of an application, which can be a method call or an exception throw. In Spring AOP, a join point is always a call to a method.

Pointcut (PointCut): join points that can be inserted for enhancement processing.

Introduction: introduction allows us to add new methods or properties to existing classes.

Weaving: add enhancement processing to the target object and create an enhanced object, which is called weaving.

Advice Notification

Advice is an implementation of facets that can perform simple weaving (this is where weaving is done). There are 5 notification types in Spring AOP, which are as follows:

The execution order of each notification is shown in the following figure:

Case coding

Requirements: add logging function to the class, as shown below:

Implementation method 1: add the method logMsg () to each class. If the number of classes is small, it is not a big problem, and if there are hundreds of classes to deal with, then the workload is very large.

Implementation method 2: realize it through aop

First, add the configuration to the mvn

Examples are as follows:

Create an interface

Public interface UserService {public void add (); public void delete (); public void update (); public void search ();}

Create a pointcut class

Public class UserServiceImpl implements UserService {public void add () {System.out.println ("add users");} public void delete () {System.out.println ("Delete users");} public void update () {System.out.println ("Update users") } public void search () {System.out.println ("query user");}

Create a class to implement @ Before notification

Import java.lang.reflect.Method; import org.springframework.aop.MethodBeforeAdvice Public class BeforeLog implements MethodBeforeAdvice {/ / method: method of the target object to be executed / / objects: parameter of the called method / / Object: target object public void before (Method method, Object [] objects, Object o) throws Throwable {System.out.println (o.getClass (). GetName () + "+ method.getName () +" method is executed ");}}

Create a class to implement @ After notification

Import java.lang.reflect.Method; import org.springframework.aop.AfterReturningAdvice Public class AfterLog implements AfterReturningAdvice {/ / returnValue return value / / method called method / / args object parameters of the called method / / target called target object public void afterReturning (Object returnValue,Method method, Object [] args Object target) throws Throwable {System.out.println ("executed" + target.getClass () .getName () + "method," + "return value:" + returnValue) }}

Edit the xml file

The test classes are as follows:

Public static void main (String [] args) {ApplicationContextcontext = new ClassPathXmlApplicationContext ("bean3.xml"); UserServiceuserService = (UserService) context.getBean ("userService"); userService.search ();}

Execute the test code and the result is as follows

The search method of com.my.demo.aop.UserServiceImpl is executed / / the before method is executed

Query the search method in user / / UserServiceImpl

Carried out.

Search method of com.my.demo.aop.UserServiceImpl. Return value: null//after method executes

You can see that because the @ Before notification @ After notification is implemented, we automatically complete the call to before and afterReturning before and after calling the method.

At this point, I believe you have a deeper understanding of "how to test with Spring AOP". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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