Spring AOP的概念与实现过程详解

<!-- https://mvnrepository.com/artifact/org.aspectj/aspectjweaver -->
<dependency>
  <groupId>org.aspectj</groupId>
  <artifactId>aspectjweaver</artifactId>
  <version>1.9.7</version>
  <scope>runtime</scope>
</dependency>

<?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">
  <bean id="userServiceImpl" class="com.mount.service.UserServiceImpl"/>
  <bean id="log" class="com.mount.log.log"/>
  <bean id="afterLog" class="com.mount.log.AfterLog"/>
  <!--  配置AOP  -->
  <aop:config>
    <!-- 切入点 expression表达式  表示从哪里开始执行   -->
    <aop:pointcut id="pointcut" expression="execution(* com.mount.service.UserServiceImpl.*(..))"/>
    <!--      执行环绕增强  -->
    <aop:advisor advice-ref="log" pointcut-ref="pointcut"/>
    <aop:advisor advice-ref="afterLog" pointcut-ref="pointcut"/>
  </aop:config>
</beans>

// 执行前  实现spring内置接口MethodBeforeAdvice
public class log implements MethodBeforeAdvice {
    public void before(Method method, Object[] args, Object target) throws Throwable {
        System.out.println(target.getClass().getName()+"执行了"+method.getName()+"方法");
    }
}
// 执行后 实现AfterReturningAdvice 
public class AfterLog implements AfterReturningAdvice {
  public void afterReturning(Object returnValue, Method method, Object[] args, Object target) throws Throwable {
    System.out.println(target.getClass().getName()+"调用了"+method.getName()+"方法"+"返回的结果为"+returnValue);
  }
}

@Test
public void test01(){
  ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
  UserService bean = context.getBean("userServiceImpl", UserService.class);
  bean.insert();
}

<!--  配置AOP 方式二  -->
<bean id="diy" class="com.mount.diyLog.diyLogImpl"/>
<aop:config>
  <!--     自定义切面 ref引入的类   -->
  <aop:aspect ref="diy">
    <aop:pointcut id="pointcut" expression="execution(* com.mount.service.UserServiceImpl.*(..))"/>
    <aop:before method="before" pointcut-ref="pointcut"/>
    <aop:after method="after" pointcut-ref="pointcut"/>
  </aop:aspect>
</aop:config>

public class diyLog {
  public void before(){
    System.out.println("===before方法执行===");
  }
  public void after(){
    System.out.println("===after方法执行===");
  }
}

<!-- SpringAop开启注解支持 -->
<aop:aspectj-autoproxy/>
<!-- 映射自定义注解实现log类 -->
<bean id="annoLog" class="com.mount.annoLog.annoLogImpl"/>

// Aspect标注该类是一个切面
@Aspect
public class annoLogImpl {
  // 前置增强
  @Before("execution(* com.mount.service.UserServiceImpl.*(..))")
  public void before(){
    System.out.println("---方法执行前---");
  }
  // 后置增强
  @After("execution(* com.mount.service.UserServiceImpl.*(..))")
  public void after(){
    System.out.println("---方法执行后---");
  }
  // 环绕增强
  @Around("execution(* com.yuqu.dao.UserMapperImpl.*(..))")
    public Object around(ProceedingJoinPoint pjp) throws Throwable {
        System.out.println("环绕前");
        Object proceed = pjp.proceed();
        System.out.println("环绕后");
        System.out.println("执行信息："+pjp.getSignature());
        return proceed;
    }
}