spring支持六种通知

aop通知1
aop通知2

5.4.5通知接口

Advice接口
Advice(通知) VS Advisor(顾问)

Advice(通知)

功能简单，只能将切面织入到目标类的所有目标方法

Advisor(顾问)

更为复杂的切面织入功能，可以指定具体的切入点,从而可以更细致地控制在哪个连接点上拦截通知.

PointcutAdvisor是顾问的一种

TODO:cj

image.png

5.4.6创建前置通知(Before advice)

用途
1.可以修改传递给方法的参数。
2.可以通过抛出异常来阻止方法的执行。

源码chapter05/simple-before-advice

package com.apress.prospring5.ch5;

import com.apress.prospring5.ch2.common.Singer;

/**
 * Created by iuliana.cosmina on 3/26/17.
 */
public class Guitarist implements Singer {

    private String lyric = "You're gonna live forever in me";

    @Override
    public void sing() {
        System.out.println(lyric);
    }

    public void song() {
        System.out.println("song:" + lyric);
    }
}

package com.apress.prospring5.ch5;

import org.springframework.aop.MethodBeforeAdvice;
import org.springframework.aop.framework.ProxyFactory;

import java.lang.reflect.Method;

public class SimpleBeforeAdvice implements MethodBeforeAdvice {
    public static void main(String... args) {
        Guitarist johnMayer = new Guitarist();

        ProxyFactory pf = new ProxyFactory();
        pf.addAdvice(new SimpleBeforeAdvice());
        pf.setTarget(johnMayer);

        Guitarist proxy = (Guitarist) pf.getProxy();

        proxy.sing();
        proxy.song();
    }

    @Override
    public void before(Method method, Object[] args, Object target)
            throws Throwable {
        System.out.println("Before '" + method.getName() + "', tune guitar.");
    }
}

执行结果

Before 'sing', tune guitar.
You're gonna live forever in me
Before 'song', tune guitar.
song:You're gonna live forever in me

5.4.7通过使用前置通知阻止方法访问