你可以写一个JDK代理的代码吗

可以，以下是一个简单的 JDK 代理的代码示例：

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

public class JDKProxyExample {

public static void main(String[] args) {
RealSubject realSubject = new RealSubject();
InvocationHandler handler = new ProxySubject(realSubject);
Subject proxySubject = (Subject) Proxy.newProxyInstance(handler.getClass().getClassLoader(),
realSubject.getClass().getInterfaces(), handler);
proxySubject.request();
}

interface Subject {
void request();
}

static class RealSubject implements Subject {
@Override
public void request() {
System.out.println("RealSubject request");
}
}

static class ProxySubject implements InvocationHandler {
private Object target;

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

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