[Java知识库]【Spring】Spring中AOP解析 上 两种动态代理方式与ProxyFactory代理工厂

1.两种动态代理方式演示

1.1 JDK动态代理

JDK的动态代理，就是在程序运行的过程中，根据被代理的接口来动态生成代理类的class文件，并加载运行的过程。要求被代理类必须实现一个接口 . 如下案例

接口

public interface TargetInterface {
    public void say();
}

被代理类

public class Target implements TargetInterface{

    @Override
    public void say() {
        System.out.println("方法被执行了");
    }

}

代理测试类

public class JDK_Proxy {

    public static void main(String[] args) {

        Target target = new Target();

        //jdk动态代理
        TargetInterface proxyInstance = (TargetInterface) Proxy.newProxyInstance(target.getClass().getClassLoader(),
                target.getClass().getInterfaces(),
                (proxy, method, args1) -> {
                    System.out.println("方法执行前");
                    Object invoke = method.invoke(target, args);
                    System.out.println("方法执行后");
                    return invoke;
                }
        );

        proxyInstance.say();

    }

}

输出结果

1.2 CGLB 动态代理

与JDK动态代理不同，cglib的目标类可以不实现接口

被代理类

public class CGLB_Target {


    public void say() {
        System.out.println("方法被执行了");
    }

}

代理测试类

/**
 * @author sz
 * @DATE 2022/4/6  18:44
 */
public class CGLB_Proxy {

    public static void main(String[] args) {
        //创建一个增强器
        Enhancer enhancer = new Enhancer();
        //设置父类  也就是被代理的类
        enhancer.setSuperclass(CGLB_Target.class);
        //设置代理逻辑
        enhancer.setCallbacks(new Callback[]{new MethodInterceptor() {
            /**
             * @param o  代理类
             * @param method  目标方法
             * @param objects  方法参数
             * @param methodProxy  代理方法
             * @return
             * @throws Throwable
             */
            @Override
            public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
                System.out.println("cglb增强_方法执行前");
                Object result = methodProxy.invokeSuper(o,objects);
                System.out.println("cglb增强_方法执行后");
                return result;
            }
        }});

        //创建代理类
        CGLB_Target cglb_target = (CGLB_Target) enhancer.create();

        cglb_target.say();
    }

}

输出结果

2.Spring封装的ProxyFactory代理工厂

1.代理工厂ProxyFactory的简单使用案例

被代理类

public class CGLB_Target {
    
    public void say() {
        System.out.println("方法被执行了");
    }

}

前置通知

public class MyBeforeAdvice implements MethodBeforeAdvice {


    @Override
    public void before(Method method, Object[] args, Object target) throws Throwable {
        System.out.println("beanfactory ---> 方法执行前");
    }
}

返回后通知

public class MyAfterReturnAdvice implements AfterReturningAdvice {

    @Override
    public void afterReturning(Object returnValue, Method method, Object[] args, Object target) throws Throwable {
        System.out.println("beanfactory --->"+method.getName()+" 方法  返回值为 "+returnValue);
    }

}

异常通知

public class MyThrowsAdvice implements ThrowsAdvice {

    public void afterThrowing(Method method, Object[] args, Object target, Exception ex)
    {

        System.out.println("beanfactory ---> 方法执行抛出异常"+ex.getMessage());
    }

}

创建代理工厂

        ProxyFactory proxyFactory = new ProxyFactory();
        proxyFactory.setTarget(new CGLB_Target());
        //前置通知
        proxyFactory.addAdvice(new MyBeforeAdvice());
        //返回后通知
        proxyFactory.addAdvice(new MyAfterReturnAdvice());
        //异常后通知
        proxyFactory.addAdvice(new MyThrowsAdvice());

        CGLB_Target proxy = (CGLB_Target) proxyFactory.getProxy();

        proxy.say();

执行结果

2.通知接口

1. `MethodBeforeAdvice 前置通知
2. `AfterReturningAdvice 返回后通知
3. `ThrowsAdvice 异常后通知

3.Advisor

在SpringAOP中一个切面类由切入点和通知组成 同样的 Advisor 也由切入点和通知组成

如果想对一个类中的say方法代理

  //创建代理工厂
        ProxyFactory proxyFactory = new ProxyFactory();
        //设置代理类
        proxyFactory.setTarget(new CGLB_Target());
        //创建advisore
        proxyFactory.addAdvisor(new PointcutAdvisor() {
            @Override
            public Pointcut getPointcut() {
               return new StaticMethodMatcherPointcut() {
                   @Override
                   public boolean matches(Method method, Class<?> targetClass) {
                        if ("say".equals(method.getName())){
                            return true;
                        }
                       return false;
                   }
               };
            }

            @Override
            public Advice getAdvice() {
                return new MyAfterReturnAdvice();
            }

            @Override
            public boolean isPerInstance() {
                return false;
            }
        });

        //创建代理类
        CGLB_Target proxy = (CGLB_Target) proxyFactory.getProxy();
        proxy.say();