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Caij nplooj ntoos hlav AOP kawm tau nyob rau hauv 30 feeb

Txheej txheem cej luam:

Npaj Kev Pab Cuam (AOP) yog lwm txoj kev mus kom ze rau qhov kev pab cuam xws li Object Oriented Programming (OOP). Txawm li cas los, AOP yuav txheeb xyuas tau OOP los ntawm kev muab lwm txoj kev xav txog qhov kev pab cuam uas muaj ib daim ntawv thov software yog tsim. There are certain similarities in how OOP and AOP are used to build software code although they are named differently – in OOP the unit of modularity is known as class while that in AOP is known as Aspect. AOP applications are developed based on the caij nplooj ntoos hlav though the Spring framework can also be used without the AOP. This article discusses how to work with Spring AOP applications.









What is AOP?

AOP, raws li qhia lub npe, is another approach to software programming. Let us understand AOP with the help of an example. A program structure for a software application contains three layers: UI layer, business logic layer and database layer. To function properly, all layers need support and communication. Support and communication can be provided by efficient logging, ruaj, transaction management, profiling and more. In AOP parlance, the various units that provide support are known as concerns. Since these concerns provide support across layers, they are also referred to as cross-cutting concerns. These cross-cutting concerns are encapsulated in what are known as Aspects. Piv txwv, a logging module can be called an AOP Aspect for logging. Aspects are user-defined and can be defined on run time basis. There are many advantages of using Aspects. Ib, they are reusable across software applications and enterprises; Ob, since they contain procedures or functions, software developers just need to use them in their program structure; Peb, Aspects reduce development overhead.

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AOP Concepts

AOP concepts drive the AOP structure and to use AOP, it is required to learn the concepts. The main concepts are explained below.

Building an application with AOP








Now that we have some knowledge of the basics of AOP, we will see below how the concepts can be used to build a code with one or more examples:

Declare an aspect –

The example below shows how an aspect can be declared:

<aop:config>

<aop:aspect id=”aopAspect” nyob =”aopBean”>

…

</aop:aspect>

</aop:config>

<taum daim id =”aopBean” hoob =”…”>

…

</taum>

Declare a pointcut –

The example of pointcut is given below:

<aop:config>

<aop:aspect id=”aopAspect” nyob =”aopBean”>

<aop:pointcut id=”aopbusinessService”

expression=”tiav(* com.techalpine.Emp.getSal(..))”/>

…

</aop:aspect>

</aop:config>

<bean id=”yBean” hoob =”…”>

…

</taum>

In the above declaration, Ib pointcut hu ua aopbusinessService yog txais thiab nws yuav phim tiav ntawm tau txais() txujci.

Txis tswv yim –

Cov piv txwv hauv qab no qhia li cas tag nrho tsib tswv yim yuav txais:

<aop:config>

<aop:aspect id=”aopAspect” nyob =”aopBean”>

<aop:pointcut id=”aopbusinessService”

expression=”tiav(* com.techalpine.aopapp.service.***(..))”/>

<!– ua ntej lub ntsiab txhais –>

<aop:ua ntej pointcut-ref=”aopbusinessService”

txujci =”doAOPTask”/>

<!– ib lub ntsiab txhais lus tom qab lub ntsiab txhais –>

<aop:tom qab pointcut-ref=”aopbusinessService”

txujci =”doAOPTask”/>

<!– ib lub ntsiab lus tom qab rov qab mus txhais cov ntsiab lus –>

<!–Txoj kev doAOPTask yuav tsum muaj parameter hu ua aopVal –>

<aop:tom qab rov qab pointcut-ref=”aopbusinessService”

rov qab=”aopVal”

txujci =”doAOPTask”/>

<!– ib lub ntsiab lus tom qab ntuav lub ntsiab txhais –>

<!–Txoj kev doAOPTask yuav tsum muaj parameter hu ua aopex –>

<aop:tom qab ntuav pointcut-ref=”aopbusinessService”

ntuav=”ex”

txujci =”doAOPTask”/>

<!– ib ncig lub ntsiab txhais –>

<aop:Nyob ib ncig ntawm pointcut-ref=”aopbusinessService”

txujci =”doAOPTask”/> …

</aop:aspect>

</aop:config>

<taum daim id =”yBean” hoob =”…”>…

</taum>

Raws li pom los ntawm cov piv txwv saum toj no, Tag nrho tsib tswv yim tau txais siv cov <aop:aspect> caij.

Thaum twg txoj no tseg, Nws yuav tso cov taw tes tej qhov nqaij ntuag thiab cov zis ntawm cov ntsiab lus. Cov zis yuav nyob ntawm tus taw tes txiav txhais thiab lub tswv yim pab.

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Xaus

While AOP seems to be a pretty good option because of the re-usability aspect of its concerns, it is not without its problems. Ib, it can be an issue debugging an AOP framework-based code because the business classes are advised only after the aspects are configured. Ob, Advise can be given only for public methods and not for methods with default, private or public visibility. Tseem, AOP can be a good option because it complements OOP so well.



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