java jdk动态代理技术

JDK动态代理必须实现接口，通过反射来动态代理方法，缺点是消耗系统性能。但是无需产生过多的代理类，避免了重复代码的产生，系统更加灵活。可以看到JDK动态代理比静态代理更加灵活。

public class JDKTest {
    public static void main(String[] args) {
        Factory factory = new Factory();
        InvocationHandler invocationHandler = new Taobao(factory);
        Usb o = (Usb) Proxy.newProxyInstance(factory.getClass().getClassLoader(),
                factory.getClass().getInterfaces(), invocationHandler);
        int sell = o.sell();
        System.out.println(sell);
    }
}

//目标接口
interface Usb {
    int sell();
}

//目标类
class Factory implements Usb {

    @Override
    public int sell() {
        return 10;
    }

}

//动态代理类
class Taobao implements InvocationHandler {
    private Object target;

    public Taobao() {
    }

    public Taobao(Object target) {
        this.target = target;
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        Object ret = method.invoke(target, args);
        int price = (int) ret;
        return price + 10;
    }
}