java 中jdk动态代理和CGLIB动态代理

• 1、jdk动态代理实践过程
• • 定义接口
  • 定义接口实现类
  • 定义代理类行为（类似于spring中aop的各种通知）
  • 代理测试
  • 打印结果
• 2、CGLIB动态代理实践过程
• • 创建被代理类
  • 创建代理工厂

public interface Person {
    public void rentHouse();
    public void rentHouse(String name);
}

public class Renter implements Person{
    @Override
    public void rentHouse() {
        System.out.println("租房");
    }
    @Override
    public void rentHouse(String name) {
        System.out.println("租房"+name);
    }
}

public class RenterInvocationHandler implements InvocationHandler {
    // 被代理类,从构造方法传入
    private T target;
    public RenterInvocationHandler(T target) {
        this.target = target;
    }
    
    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        System.out.println("租客和中介交流");
        // 调用
        Object result = method.invoke(target, args);
        System.out.println("租房结束");
        return result;
    }
}

public static void main(String[] args) {
        // 被代理类
        Person renter = new Renter();

        RenterInvocationHandler renterInvocationHandler = new RenterInvocationHandler<>(renter);

        // 传入类加载器,代理类需要实现的接口,handler
        Person renterProxy = (Person)Proxy.newProxyInstance(Person.class.getClassLoader(),new Class[]{Person.class},renterInvocationHandler);

        renterProxy.rentHouse();
        System.out.println();
        renterProxy.rentHouse("越美国际");
    }

租客和中介交流
租房
租房结束

租客和中介交流
租房越美国际
租房结束

public class Renter2 {
    public void rentHouse() {
        System.out.println("租房");
    }
    public void rentHouse(String name) {
        System.out.println("租房"+name);
    }
}

public class ProxyFactory implements MethodInterceptor {
    // cglib工具类
    private Enhancer en = new Enhancer();
    // 被代理对象
    private T target;

    public ProxyFactory(T target) {
        this.target = target;
    }

    
    public T getProxyInstance(Class clazz){
        // 父类
        en.setSuperclass(clazz);
        // 回调类方法所在类
        en.setCallback(this);
        return (T)en.create();
    }

    
    @Override
    public Object intercept(Object obj, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {
        System.out.println("中介和租客交流");
        Object result = method.invoke(target,args);
        System.out.println("租房结束");
        return result;
    }

    
    public static void main(String[] args) {
        ProxyFactory renter2ProxyFactory = new ProxyFactory<>(new Renter2());
        Renter2 proxyInstance = renter2ProxyFactory.getProxyInstance(Renter2.class);
        
        proxyInstance.rentHouse();
        System.out.println();
        proxyInstance.rentHouse("越美国际");

    }
}