【sping揭秘】17、@Around，@Introduction

package cn.cutter.start.bean;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.stereotype.Component;

/**
 *
 * @author xiaof
 *
 */
@Component
public class AroundTestBean {

    private static final Log logger = LogFactory.getLog(AroundTestBean.class);

    public void method1() {
        logger.info("AroundTestBean 执行方法1");
    }

    public void method2(String param1) {
        logger.info("AroundTestBean 执行方法1" + param1);
    }

    public void method3() {
        logger.info("AroundTestBean 执行方法1");
    }

    public void method4() {
        logger.info("AroundTestBean 执行方法1");
    }

}

package cn.cutter.start.aop;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.springframework.stereotype.Component;

/**
 * 环绕拦截
 * @author xiaof
 *
 */
@Component
@Aspect
public class AroundAspect {

    private static final Log logger = LogFactory.getLog(AroundAspect.class);

    @Pointcut("execution(* cn.cutter.start.bean.AroundTestBean.method1(..))")
    public void pointcut1() {}

    @Pointcut("execution(* cn.cutter.start.bean.AroundTestBean.method2(..))")
    public void pointcut2() {}

    @Pointcut("execution(* cn.cutter.start.bean.AroundTestBean.method3(..))")
    public void pointcut3() {}

    @Pointcut("execution(* cn.cutter.start.bean.AroundTestBean.method4(..))")
    public void pointcut4() {}

    /**
     * 注意环绕拦截，必须有参数ProceedingJoinPoint joinPoint，而且必须是第一个
     * @param joinPoint
     */
    @Around("pointcut1()")
    public void around1(ProceedingJoinPoint joinPoint) {
        //环绕拦截，拦截 cn.cutter.start.bean.AroundTestBean.method1 这个方法
        try {
            logger.info("AroundAspect 环绕拦截的try中开始方法，然后执行对应的方法");
            Object o = joinPoint.proceed();
        } catch (Throwable e) {
            e.printStackTrace();
        } finally {
            logger.info("AroundAspect 环绕拦截的最终方法！");
        }

    }

    @Around("pointcut2() && args(taskName)")
    public void around2(ProceedingJoinPoint joinPoint, String taskName) {
        //环绕拦截，拦截 cn.cutter.start.bean.AroundTestBean.method1 这个方法
        try {
            logger.info("AroundAspect 环绕拦截的try中开始方法，然后执行对应的方法,参数是：" + taskName);
            Object o = joinPoint.proceed();
        } catch (Throwable e) {
            e.printStackTrace();
        } finally {
            logger.info("AroundAspect 环绕拦截的最终方法！");
        }

    }

}

@Test
    public void testAop6() {
        ApplicationContext ctx = this.before();

        AroundTestBean att = (AroundTestBean) ctx.getBean("aroundTestBean");

        att.method2("param test");

    }

@Introduction

我们先首先明确一点，这个注解是用来给原来的对象添加新的行为逻辑的

说白了就是给类扩展自定义方法

我们定义个类，作为添加方法的目标

package cn.cutter.start.bean;

import org.springframework.stereotype.Component;

@Component
public class IntroductionTestBean {

}

好的，现在如果我们想给这个空的对象，添加一个，或者许多方法，怎么办呢？？？

不急，我们先把要进行添加的方法准备好

package cn.cutter.start.introduction;

/**
 * 用来使用spring的扩展增强，@introduction
 * 用来给对象进行添加方法
 * @author xiaof
 *
 */
public interface TestIntroduction1 {

    public void dosomething();

}

这里是一个接口，里面有个dosomething的方法，我们可以实现多种方式，然后添加的效果也可以多种多样

我们实现两个类

package cn.cutter.start.introduction.impl;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import cn.cutter.start.introduction.TestIntroduction1;

public class TestIntroduction1Impl implements TestIntroduction1 {

    private final Log logger = LogFactory.getLog(TestIntroduction1Impl.class);

    @Override
    public void dosomething() {
        // TODO Auto-generated method stub
        logger.info("introduction 操作 dosomething！！！");
    }

}

package cn.cutter.start.introduction.impl;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import cn.cutter.start.introduction.TestIntroduction1;

public class TestIntroduction1Impl2 implements TestIntroduction1 {

    private final Log logger = LogFactory.getLog(TestIntroduction1Impl2.class);

    @Override
    public void dosomething() {
        logger.info("这里是另外一个实现接口的方法");

    }

}

好，要添加的目标有了，要添加的配料也有了，是时候炒一盘了

package cn.cutter.start.aop;

import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.DeclareParents;
import org.springframework.stereotype.Component;

import cn.cutter.start.introduction.TestIntroduction1;
import cn.cutter.start.introduction.impl.TestIntroduction1Impl;
import cn.cutter.start.introduction.impl.TestIntroduction1Impl2;

@Component
@Aspect
public class IntroductionAspect {

    @DeclareParents(
            value="cn.cutter.start.bean.IntroductionTestBean",
            defaultImpl=TestIntroduction1Impl.class)
    public TestIntroduction1 testIntroduction1;

//    @DeclareParents(
//            value="cn.cutter.start.bean.IntroductionTestBean",
//            defaultImpl=TestIntroduction1Impl2.class)
//    public TestIntroduction1 testIntroduction2;

}

看到了么，这里@DeclareParents中的两个参数，一个是目标，一个是配置调料

Value是目标，defaultImpl是调料

测试一波：

@Test
    public void testAopIntroduction() {
        ApplicationContext ctx = this.before();

        IntroductionTestBean att = (IntroductionTestBean) ctx.getBean("introductionTestBean");
//        Object obj = (IntroductionTestBean) ctx.getBean("introductionTestBean");

        TestIntroduction1 test = (TestIntroduction1) att;
        test.dosomething();
//
//        TestIntroduction1 test2 = (TestIntroduction1Impl2) obj;
//        test2.dosomething();

    }