AOP-面向切面编程

1、AOP简介：

URL：https://baike.baidu.com/item/AOP/1332219?fr=aladdin

2、用例：

（1）添加spring aop支持AspectJ依赖。

<!-- spring aop 支持-->
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-aop</artifactId>
    <version>4.3.11.RELEASE</version>
</dependency>
<!-- aspectj 支持-->
<dependency>
    <groupId>org.aspectj</groupId>
    <artifactId>aspectjrt</artifactId>
    <version>1.8.8</version>
</dependency>
<dependency>
    <groupId>org.aspectj</groupId>
    <artifactId>aspectjweaver</artifactId>
    <version>1.8.10</version>
</dependency>

（2）编写拦截规则注解

package com.houkang.aop;

import java.lang.annotation.*;

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Action {
    String name();
}

（3）编写使用注解的被拦截类

package com.houkang.aop;

import org.springframework.stereotype.Service;

@Service
public class DemoAnnotationService {
    @Action(name = "注解式拦截的add操作")
    public void add(){}
}

（4）编写使用方法规则拦截类

package com.houkang.aop;

import org.springframework.stereotype.Service;

@Service
public class DemoMethodService {
    public void add(){}
}

（5）编写切面

package com.houkang.aop;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.stereotype.Component;

import java.lang.reflect.Method;

@Aspect
@Component
public class LogAspect {

    @Pointcut("@annotation(com.houkang.aop.Action)")
    public void annotationPointCut() {
    }

    @After("annotationPointCut()")
    public void after(JoinPoint joinPoint) {
        MethodSignature signature = (MethodSignature) joinPoint.getSignature();
        Method method = signature.getMethod();
        Action action = method.getAnnotation(Action.class);
        System.out.println("注解式拦截 " + action.name());
    }

    @Before("execution(* com.houkang.aop.DemoMethodService.* (..))")
    public void before(JoinPoint joinPoint) {
        MethodSignature signature = (MethodSignature) joinPoint.getSignature();
        Method method = signature.getMethod();
        System.out.println("方法规则式拦截," + method.getName());
    }

}

（6）配置类

package com.houkang.aop;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.EnableAspectJAutoProxy;

@Configuration
@ComponentScan("com.houkang.aop")
@EnableAspectJAutoProxy
public class AopConfig {
}

（7）运行

package com.houkang.aop;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;


public class Main {

    public static void main(String[] args) {
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(AopConfig.class);
        DemoAnnotationService demoAnnotationService = context.getBean(DemoAnnotationService.class);
        DemoMethodService demoMethodService = context.getBean(DemoMethodService.class);
        demoAnnotationService.add();
        demoMethodService.add();
        context.close();
    }
}

（8）运行结果：

一月 29, 2018 10:06:17 上午 org.springframework.context.annotation.AnnotationConfigApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@254989ff: startup date [Mon Jan 29 10:06:17 CST 2018]; root of context hierarchy
注解式拦截 注解式拦截的add操作
方法规则式拦截,add
一月 29, 2018 10:06:17 上午 org.springframework.context.annotation.AnnotationConfigApplicationContext doClose
信息: Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@254989ff: startup date [Mon Jan 29 10:06:17 CST 2018]; root of context hierarchy

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