SpringAOP之within和target的使用和区别

SpringAOP之within和target

目录

• SpringAOP之within和target
• 1、概述
• 2、约定
• 3、示例
• 4、配置切面

1、概述

@within和@target是在配置切点的时候使用到的两个修饰符，都是基于注解来配置切点。

比如当前有注解@A

• "@within(com.annotation.other.A1)"该配置就是：如果某个类上标注了注解@A，那么该类中的所有方法就会被匹配为切点，并且该类的子类中没有重写的父类方法也会被匹配为切点；
• "@target(com.annotation.other.A1)"该配置就是：如果某个类上标注了注解@A，那么该类中的所有方法就会被匹配为切点；

2、约定

本文说的子类和父类关系都是类之间的子类和父类。不涉及注解继承，也就是自定义注解中没有标注元注解–@Inherited。

@within和@target正确用法是 "@within/@target(注解的全类名)"，以下简写为 "@within/@target(@A1)"

3、示例

//注解@A1
@Retention(RetentionPolicy.RUNTIME)
@Target( ElementType.TYPE)
public @interface A1 {
}

//注解@A2
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface A2 {
}

三个有继承关系的类：

@A1
public  class Human {

    public void say(String sentence)
    {
        System.out.println("Human says:" + sentence);
    }

    public void run()
    {
        System.out.println("Human runs." );
    }

    public void jump()
    {
        System.out.println("Human jump." );
    }
}


@A2
public class Man  extends Human{

    @Override
    public void run()
    {
        System.out.println("Man runs." );
    }
    
    public void testMan(){
        System.out.println("Man testMan." );
    }
}

public class Boy extends Man{

    @Override
    public void jump()
    {
        System.out.println("Boy jump." );
    }

    public void test(){
        System.out.println("Bot test...");
    }
}

对应的类图：

4、配置切面

@Aspect
@Component
public class HumanAspect {

    @Before("@within(com.annotation.other.A1)")
    public void execute1(){
        System.out.println("@within --- A1");
    }

    @Before("@target(com.annotation.other.A1)")
    public void execute2(){
        System.out.println("@target --- A1");
    }

    @Before("@within(com.annotation.other.A2)")
    public void execute3(){
        System.out.println("@within --- A2");
    }

    @Before("@target(com.annotation.other.A2)")
    public void execute4(){
        System.out.println("@target --- A2");
    }
}

测试类：

public class SpringApplication {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(Config.class);
        Human human = context.getBean("human",Human.class);
        System.out.println("--------------- This is a Human ---------------");
        human.say("hello");
        human.jump();
        human.run();
        System.out.println("--------------- This is a man ---------------");
        Man man = context.getBean("man", Man.class);
        man.testMan();
        man.run();

        System.out.println("--------------- This is a boy ---------------");
        Boy boy = context.getBean("boy", Boy.class);
        boy.jump();
        boy.test();

    }
}

测试结果：

--------------- This is a Human ---------------
@within --- A1
@target --- A1
Human says:hello
@within --- A1
@target --- A1
Human jump.
@within --- A1
@target --- A1
Human runs.
--------------- This is a man ---------------
@within --- A2
@target --- A2
Man testMan.
@within --- A2
@target --- A2
Man runs.
--------------- This is a boy ---------------
Boy jump.
Bot test...

参考链接：https://blog.csdn.net/qq_36917119/article/details/108123440