BridgeLi's Blog

说实话，由于我个人某些基础不是很牢固，所以前一段时间关于 Spring Aop 踩了一个坑，其实很简单，今天就记录一下，先说结论：

不能被 Spring AOP 增强的方法：

1. 基于接口的动态代理：除 public 外的其它所有的方法，此外 public static 也不能被增强
2. 基于 CGLib 的动态代理：private、static、final 的方法，也就是只有 public 和 protected 可以，但是要注意切入点语法的配置

测试用例如下，pom 文件：

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.7.7</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>4.3.11.RELEASE</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.8.10</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>4.3.11.RELEASE</version>
        </dependency>

配置文件就比较简单了：

<?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: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-2.5.xsd
           http://www.springframework.org/schema/context
           http://www.springframework.org/schema/context/spring-context-2.5.xsd
           http://www.springframework.org/schema/aop
           http://www.springframework.org/schema/aop/spring-aop-2.5.xsd">
    <context:annotation-config/>
    <context:component-scan base-package="cn.bridgeli"/>
    <aop:aspectj-autoproxy/>

</beans>

切面类：

package cn.bridgeli.demo.aop;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
import org.springframework.stereotype.Component;

@Aspect
@Component
public class LogInterceptor {
    //    @Pointcut("execution(* * com.bjsxt.service..*.add(..))")
    @Pointcut("execution(* cn.bridgeli.demo.service..*.*(..))")
    public void myMethod() {
    }


    @Before("myMethod()")
    public void before() {
        System.out.println("method before");
    }

    @Around("myMethod()")
    public void aroundMethod(ProceedingJoinPoint pjp) throws Throwable {
        System.out.println("method around start");
        pjp.proceed();
        System.out.println("method around end");
    }

}

测试类：

package cn.bridgeli.demo.service;

import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.stereotype.Service;

@Service("userService")
public class UserService {

    /**
     * private方法因为修饰符访问权限的控制，无法被子类覆盖
     */
    private void method1() {
        System.out.println("method1 executed");
    }

    /**
     * final 方法无法被子类覆盖
     */
    private final void method2() {
        System.out.println("method2 executed");
    }

    /**
     * static 方法是类级别的方法，无法被子类覆盖
     */
    private static void method3() {
        System.out.println("method3 executed");
    }

    /**
     * public 方法可以被子类覆盖，因此可以被动态字节码增强
     */
    public void method4() {
        System.out.println("method4 executed");
    }

    /**
     * final 方法无法被子类覆盖
     */
    public final void method5() {
        System.out.println("method5 executed");
    }

    /**
     * protected 方法可以被子类覆盖，因此可以被动态字节码增强
     */
    protected void method6() {
        System.out.println("method6 executed");
    }

    /**
     * 测试
     *
     * @param args
     */
    public static void main(String[] args) {

        ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");
        UserService userService = (UserService) ctx.getBean("userService");
        System.out.println("initContext successfully");

        System.out.println("before method1");
        userService.method1();
        System.out.println("after1 method1");

        System.out.println("before method2");
        userService.method2();
        System.out.println("after1 method2");

        System.out.println("before method3");
        method3();
        System.out.println("after1 method3");

        System.out.println("before method4");
        userService.method4();
        System.out.println("after1 method4");

        System.out.println("before method5");
        userService.method5();
        System.out.println("after1 method5");

        System.out.println("before method6");
        userService.method6();
        System.out.println("after1 method6");

        if (ctx != null) {
            ctx.close();
        }
        System.out.println("close context successfully");
    }
}

参考资料：
1. http://jinnianshilongnian.iteye.com/blog/1857189
2. https://blog.csdn.net/yangshangwei/article/details/78094196