一筋蓖、動(dòng)態(tài)簡(jiǎn)單說明

• jdk動(dòng)態(tài)代理：利用反射機(jī)制荤西，基于接口創(chuàng)建被代理對(duì)象的代理實(shí)例（僅支持基于接口進(jìn)行代理澜搅，無法對(duì)類進(jìn)行代理）代理類通過實(shí)現(xiàn)InvocationHander.invok();
• cglib動(dòng)態(tài)代理：基于繼承的方式代理目標(biāo)類和方法，但是不能是final 類型的;
  通過實(shí)現(xiàn)MethodInterceptor.interceptor();
  CGLIB$intercept() 方法實(shí)際上是委托給 DynamicAdvisedInterceptor 的 intercept(),這個(gè)過程是由CGLIB庫(kù)通過字節(jié)碼生成技術(shù)(ASM)完成的邪锌。

二勉躺、動(dòng)態(tài)代理簡(jiǎn)單使用

public interface A {
    public void a();
    public void b();
}
public class Aimpl implements A{
    @Override
    public void a() {
        System.out.println("執(zhí)行方法A~~~~");
    }

    @Override
    public void b() {
        System.out.println("執(zhí)行方法B~~~~");
    }
}

jdk動(dòng)態(tài)代理：

public class JdkProxyTest implements InvocationHandler {

    private A a;

    public JdkProxyTest(A a){
        this.a = a;
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        System.out.println("jdk代理-invoke執(zhí)行~~~~");
        return method.invoke(a,args);
    }

    public static A newProxyInstance(A a){
        return (A) Proxy.newProxyInstance(JdkProxyTest.class.getClassLoader(),new Class[]{A.class},new JdkProxyTest(a));
    }

    public static void main(String[] args) {
        A a = new Aimpl();
        A jdkProxy = JdkProxyTest.newProxyInstance(a);
        jdkProxy.a();
        jdkProxy.b();
    }
}

輸出：

image.png

cglib動(dòng)態(tài)代理：

public class CglibProxyTest implements MethodInterceptor {

    @Override
    public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {

        System.out.println("cglib代理-interceptor執(zhí)行~~~~");

        return methodProxy.invokeSuper(o,objects);
    }


    public static  <T extends A>  A newProxyInstance(Class<T> targetInstanceClazz){
        Enhancer enhancer = new Enhancer();
        enhancer.setCallback(new CglibProxyTest());
        enhancer.setSuperclass(targetInstanceClazz);
        enhancer.setInterfaces(new Class[]{A.class});

        return  (A) enhancer.create();
    }
    public static void main(String[] args) {
        A cglibAgent = CglibProxyTest.newProxyInstance(Aimpl.class);
        cglibAgent.a();
        cglibAgent.b();
    }
}

輸出：

image.png

三、spring集成動(dòng)態(tài)代理源碼解析

1. 使用@EnableAspectJAutoProxy 確認(rèn)使用哪種代理秃流。

• 參數(shù)：proxyTargetClass true表示使用cglib代理赂蕴，false表示使用jdk代理柳弄；參數(shù)
• 參數(shù)：exposeProxy 值為true 表示暴露代理類舶胀，目標(biāo)類中可以嵌套代理類，使用AopContext.currentProxy() 獲取代理類

2. 源碼：

• AbstractApplicationContext.java

public void refresh() throws BeansException, IllegalStateException {
        synchronized (this.startupShutdownMonitor) {
            
                      ...
            try {
            ... 
                finishBeanFactoryInitialization(beanFactory);
                        ...
    
            }
                        ...
        }
    }

• 創(chuàng)建bean, AbstractAutowireCapableBeanFactory.createBean()

  
  
  createBean.png

applyBeanPostProcessorsBeforeInstantiation.png

applyBeanPostProcessorsBeforeInstantiation.png

• AbstractAutoProxyCreator.postProcessBeforeInstantiation()

postProcessBeforeInstantiation.png

• AspectJAwareAdvisorAutoProxyCreator.shouldSkip()

  
  
  shouldSkip.png

• AnnotationAwareAspectJAutoProxyCreator.findCandidateAdvisors()

findCandidateAdvisors.png