The simple steps of aop are as follows, in fact, there are three simple steps:

Preparatory steps: import Maven dependencies, spring configuration files, and read configuration files in main

Aspect class configuration

Entry point configuration

Cut-in notification configuration

Maven dependencies

Common maven dependencies are as follows

        <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.3.21</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-expression</artifactId>
            <version>5.3.21</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
            <version>5.3.21</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>5.3.21</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>5.3.21</version>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjrt</artifactId>
            <version>1.9.1</version>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.9.1</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.3.21</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>5.3.21</version>
        </dependency>
        <dependency>
            <groupId>commons-logging</groupId>
            <artifactId>commons-logging</artifactId>
            <version>1.2</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.42</version>
            <scope>runtime</scope>
        </dependency>
    </dependencies>

ioc configuration file

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
         http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
         http://www.springframework.org/schema/context
         http://www.springframework.org/schema/context/spring-context-3.0.xsd http://www.springframework.org/schema/aop https://www.springframework.org/schema/aop/spring-aop.xsd">

    <!--    使用基于注解的包扫描器-->
    <context:component-scan base-package="com.itheima"/>
    <!--    开启基于注解的aop-->
    <aop:aspectj-autoproxy/>

Aop usage: Method cut-in based on annotations

Method entry requires the following steps

Create facet classes ,

Specify the pointcut configuration (target method) through the pointcut() empty method

Create the cut-in notification configuration in the aspect class , and perform method cut-in on the point-cut point

Aspect class: the class where the cut-in method is located, specified by @Aspect

1. Entry point:

Specify the target method to cut in, configuration syntax

@Pointcut("execution(* com.itheima.aop..*.*(..)))")

symbol	meaning
First *	Indicates the type of return value, * refers to any type
com.itheima.aop..	The package name of the target method.. refers to this package and sub-packages. refers to this package
the second *	Indicates the class name, * means all classes.
The third *	Indicates the method name, * means all methods.
(..)	Indicates parameter type.. Indicates any parameter type

2. Cut-in notification : cut-in method to each state of the point-cut point

state contains

@After("pointcut()")	post notification	After the pointcut method is executed, execute this method
@Before("entry point()")	advance notice	Execute this method before the pointcut method executes
@AfterReturning("entry point()")	return notice	After the pointcut method returns a value, execute this method
@AfterThrowing("entry point()")	Exception notification	Execute this method after an exception occurs in the pointcut method
@Around("entry point()")	surround notification	通过ProceddingJoinPoint参数在目标方法任何位置切入方法

通知内常用参数

ProcedingJoinPoint 正在执行的目标方法

JoinPoint 目标方法

aop使用:基于注解进行方法切入

方法切入需要以下几步

创建切面类,

通过<aop:pointcut>指定切入点（目标方法）

通过<aop:before>等创建切面类内的切入通知，对切入点进行方法切入

<!--    1.创建切面类-->
<bean id="aopTestObject" class="com.itheima.aop.AopTestObject"></bean>

<aop:config>
    <!--        2.切入点配置-->
    <aop:pointcut id="pointcut01" expression="execution(* com.itheima.aop..*.*(..))"/>

    <aop:aspect ref="aopTestObject">
        <!--            3.切入通知配置-->
        <aop:after method="需要指定切面类内的方法" pointcut-ref="pointcut01"/>
        <aop:before method="需要指定切面类内的方法" pointcut-ref="pointcut01"/>

    </aop:aspect>
</aop:config>

1.切入点:

指定要切入的目标方法，配置语法

"execution(* com.itheima.aop..*.*(..)))"

符号	含义
第一个 *	表示返回值的类型,*指任何类型
com.itheima.aop..	目标方法所在包名 ..指此包及子包下 .指此包下
第二个 *	表示类名，*即所有类。
第三个 *	表示方法名，*即所有方法。
(..)	表示参数类型 ..表示任何参数类型

2.切入通知：向切入点的各个状态下切入方法

状态包含

<aop:after pointcut-ref="切入点id">	后置通知	在切入点方法执行完后，执行此方法
<aop:before pointcut-ref="切入点id">	前置通知	在切入点方法执行之前，执行此方法
<aop:after-returning pointcut-ref="切入点id">	返回通知	在切入点方法返回值后，执行此方法
<aop:after-throwing pointcut-ref="切入点id">	异常通知	在切入点方法发生异常后，执行此方法
<aop:around pointcut-ref="切入点id">	环绕通知	在目标方法任何位置切入方法

Basic use of Spring-aop