Question

本课题回答处理抽象方法类型;但如何代理方法的非抽象部分？ Implementing abstract methods at runtime?

如何执行以下操作以致电sayHello()？

package cglibtest;

import java.lang.reflect.Method;

import net.sf.cglib.proxy.Enhancer;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;

public class CGLibTest
{
    public static void main(String... args)
    {
        MyAbstract instance = (MyAbstract)Enhancer.create(MyAbstract.class, new MyInterceptor(42));
        System.out.println("Value from instance: " + instance.valueMethod());
        System.out.println("Value from instance: " + instance.sayHello());
    }

    public static class MyInterceptor implements MethodInterceptor
    {
        private final Object constantValue;

        public MyInterceptor(Object constantValue)
        {
            this.constantValue = constantValue;
        }

        @Override
        public Object intercept(Object obj, Method method, Object[] args,
                MethodProxy proxy) throws Throwable
        {
            if ("valueMethod".equals(method.getName()))
                return(constantValue);
            else
                return(null);
        }
    }

    public static abstract class MyAbstract
    {
        public abstract int valueMethod();
         public String sayHello() { return "Hello" };
    }
}

Answer 1

您创建的拦截器已经覆盖了所有方法，无论是否为abstract。您似乎错过的是如何调用已覆盖的原始方法：

public Object intercept(Object obj, Method method, Object[] args,
        MethodProxy proxy) throws Throwable
{
    if ("valueMethod".equals(method.getName()))
        return constantValue;
    else if("sayHello".equals(method.getName())) {
        System.out.println("before original sayHello()");
        // equivalent of saying super.sayHello() inside subclass
        Object result=proxy.invokeSuper(obj, args);
        System.out.println("after original sayHello()");
        return result;
    }
    else return null;
}

你会如何调用抽象类的非抽象方法？

1 个答案: