动态代理举例说明

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

interface Calculator {
    int add(int a, int b);
}

class CalculatorHandler implements InvocationHandler {
    private final Calculator target;

    public CalculatorHandler(Calculator target) {
        this.target = target;
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        System.out.println("Before method call");
        Object result = method.invoke(target, args);
        System.out.println("After method call");
        return result;
    }
}

public class DynamicProxyExample {
    public static void main(String[] args) {
        Calculator realCalculator = (a, b) -> a + b;
        Calculator proxyCalculator = (Calculator) Proxy.newProxyInstance(
            Calculator.class.getClassLoader(),
            new Class[] { Calculator.class },
            new CalculatorHandler(realCalculator)
        );

        int result = proxyCalculator.add(2, 3);
        System.out.println("Result: " + result);
    }
}