spring的APO

一、pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>A02spring</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <!--https://mvnrepository.com/artifact/org.springframework/spring-context-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.8.RELEASE</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.aspectj/aspectjweaver -->
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.9.6</version>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

二、spring的xml配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/aop
        https://www.springframework.org/schema/aop/spring-aop.xsd">

    <!--要被增强的类-->
    <bean id="sourceMethod" class="com.wuxi.services.impl.StudentServiceImpl"></bean>
    <!--增强的功能所在的类-->
    <bean id="adviceMethod" class="com.wuxi.utils.LoggerService"></bean>

<!--
切入点表达式
    全通配符写法：* *..*.*(..)
    修饰符可省略，*既作为通配符，也作为占位符，..意味多级包或多个参数
通知类型（增强功能的方式）
    前置通知（aop:before）：在切入点之前运行
    后置通知（aop:after-returning）：在切入点正常运行之后运行
    异常通知（aop:after-throwing）：切入点运行发生异常时运行
    最终通知（aop:after）：不管切入点有没有发生异常都会执行
    环绕通知（aop:around）：相当于前置通知+后置通知+异常通知+最终通知
-->
    <aop:config>
        <aop:pointcut id="pt"
                      expression="execution(public void com.wuxi.services.impl.StudentServiceImpl.removeStudent())"/>
        <!--ref：增强的功能所在的类-->
        <aop:aspect id="logAdvice" ref="adviceMethod">
            <!--method：增强的功能具体方法-->
            <!--pointcut：被增强的切入点的表达式-->
            <!--<aop:before method="printLog" pointcut="execution(public void com.wuxi.services.impl.StudentServiceImpl.modifyStudent(String))"></aop:before>-->
            <!--<aop:pointcut id="pt" expression="execution(public void com.wuxi.services.impl.StudentServiceImpl.modifyStudent(String))"/>-->
            <aop:before method="printLog" pointcut-ref="pt"></aop:before>
            <aop:around method="printAroundLog"
                        pointcut="execution(public String com.wuxi.services.impl.StudentServiceImpl.findStudent())"></aop:around>
        </aop:aspect>
    </aop:config>

</beans>

三、要被增强的类的接口

package com.wuxi.services;

public interface StudentService {
    void modifyStudent(String name);

    String findStudent();

    void removeStudent();
}

四、要被增强的类

package com.wuxi.services.impl;

import com.wuxi.services.StudentService;

public class StudentServiceImpl implements StudentService {
    @Override
    public void modifyStudent(String name) {
        System.out.println("修改" + name);
    }

    @Override
    public String findStudent() {
        System.out.println("查询");
        return "孟美岐";
    }

    @Override
    public void removeStudent() {
        System.out.println("删除");
    }
}

五、增强的功能所在的类（通知类）

package com.wuxi.utils;

import org.aspectj.lang.ProceedingJoinPoint;

public class LoggerService {
    public void printLog() {
        System.out.println("打印日志");
    }

    public Object printAroundLog(ProceedingJoinPoint pjp) {
        Object proceed = null;
        try {
            System.out.println("环绕前置通知");
            Object[] args = pjp.getArgs();
            proceed = pjp.proceed(args);
            System.out.println("环绕后置通知");
        } catch (Throwable throwable) {
            System.out.println("环绕异常通知");
            throwable.printStackTrace();
        } finally {
            System.out.println("环绕最终通知");
        }
        return proceed;
    }
}

六、测试

package com.wuxi.tests;

import com.wuxi.services.StudentService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MySpringTest {
    public static void main(String[] args) {
        ApplicationContext ac = new ClassPathXmlApplicationContext("application.xml");

        StudentService studentService = (StudentService) ac.getBean("sourceMethod");
        // studentService.removeStudent();
        studentService.findStudent();
    }
}

七、APO的理解

　　APO（面向切面编程）就是在不改变原来方法的原则下，对方法的功能进行增强。思想是使用的是动态代理