spring-AOP基础入门_srring aop入门-优快云博客

本文链接：https://blog.youkuaiyun.com/lazy_zhuo/article/details/123773065

本文详细介绍了一种常用的设计模式——面向切面编程(AOP)在Java中的应用实践，包括使用Spring框架进行AOP编程的具体步骤，从引入依赖包、定义接口与实现类，到通过Spring API实现方法前后置通知，再到自定义类实现AOP及使用注解的方式，最后提供了测试代码。

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1、导入依赖包

<dependency>
   <groupId>org.aspectj</groupId>
   <artifactId>aspectjweaver</artifactId>
   <version>1.9.4</version>
</dependency>

2、接口

public interface UserService {
    public void add();
    public void delete();
    public void update();
    public void select();
}

3.实现类

public class UserServiceImp implements UserService{

    @Override
    public void add() {
        System.out.println("增加了一个用户");
    }

    @Override
    public void delete() {
        System.out.println("删除了一个用户");
    }

    @Override
    public void update() {
        System.out.println("增更新了一个用户");
    }

    @Override
    public void select() {
        System.out.println("查找了一个用户");
    }
}

4、实现aop接口
4.1、方法执行前

public class Log implements MethodBeforeAdvice {
    @Override
    //method:目标对象的方法
    //args:参数
    //target:目标对象
    public void before(Method method, Object[] args, Object target) throws Throwable {
        System.out.println(target.getClass().getName()+"的"+method.getName()+"被执行了");
    }
}

4.1、方法执行后

public class AfterLog implements AfterReturningAdvice {
    @Override
    //returnValue：返回值
    public void afterReturning(Object returnValue, Method method, Object[] args, Object target) throws Throwable {
        System.out.println("执行了"+method.getName()+"方法，返回结果为："+returnValue);
    }
}

方式一：使用spring的API接口
5、类注入到spring中:

<?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.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd">
    <bean id="userService" class="com.zhuo.service.UserServiceImp"/>
    <bean id="log" class="com.zhuo.log.Log"/>
    <bean id="afterLog" class="com.zhuo.log.AfterLog"/>
    <!--方式一：使用Spring API-->
    <aop:config>
        <!--切入点 ：expression表达式：execution()执行的位置-->
        <aop:pointcut id="pointcut" expression="execution(* com.zhuo.service.UserServiceImp.*(..))"/>
        <!--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>

6、测试

public class MyTest {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        //动态代理的是接口
        UserService userService = context.getBean("userService", UserService.class);
        userService.add();
    }
}

方式二：自定义类实现AOP
5、自定义类

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

<?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.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd">
    <bean id="userService" class="com.zhuo.service.UserServiceImp"/>
    <bean id="log" class="com.zhuo.log.Log"/>
    <bean id="afterLog" class="com.zhuo.log.AfterLog"/>
    <bean id="diy" class="com.zhuo.diy.DiyPointCut"/>
    
    <aop:config>
        <aop:aspect ref="diy"> <!--切面-->
            <!--切入点 expression表达式：execution()执行的位置-->
            <aop:pointcut id="point" expression="execution(* com.zhuo.service.UserServiceImp.*(..))"/>
            <!--通知-->
            <aop:before method="before" pointcut-ref="point"/>
            <aop:after method="after" pointcut-ref="point"/>
        </aop:aspect>
    </aop:config>
</beans>

6、测试

public class MyTest {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        //动态代理的是接口
        UserService userService = context.getBean("userService", UserService.class);
        userService.add();
    }
}

方式三：注解
1、编写类

@Aspect //标注这个类是一个切面
public class AnnotationPointCut {

    @Before("execution(* com.zhuo.service.UserServiceImp.*(..))")
    public void before(){
        System.out.println("=====方法执行前====");
    }

    @After("execution(* com.zhuo.service.UserServiceImp.*(..))")
    public void after(){
        System.out.println("=====方法执行后====");
    }

    //在环绕增强中，我们可以给定一个参数，代表我们要获取处理切入的点
    @Around("execution(* com.zhuo.service.UserServiceImp.*(..))")
    public void around(ProceedingJoinPoint jp) throws Throwable {
        System.out.println("=====环绕前====");

        //执行方法
        Object proceed = jp.proceed();

        System.out.println("=====环绕前====");
    }
}

2、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: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.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd">
    <bean id="userService" class="com.zhuo.service.UserServiceImp"/>
    <bean id="log" class="com.zhuo.log.Log"/>
    <bean id="afterLog" class="com.zhuo.log.AfterLog"/>

    <bean id="annotationPointCut" class="com.zhuo.diy.AnnotationPointCut"/>
    <!--开启注解支持-->
    <aop:aspectj-autoproxy/>
</beans>

3、测试

public class MyTest {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        //动态代理的是接口
        UserService userService = context.getBean("userService", UserService.class);
        userService.add();
    }
}