如何模拟URLconnection，以便在java中更改getLastModified方法的返回值？

import java.io.IOException;
import java.net.URL;
import java.net.URLConnection;

public class ModifiedURLConnection extends URLConnection {
    private long lastModified;

    protected ModifiedURLConnection(URL url) {
        super(url);
    }

    @Override
    public void connect() throws IOException {
        // 连接到URL或资源
        // 可以在这里获取真实的lastModified值
        lastModified = System.currentTimeMillis(); // 这里假设将当前时间作为lastModified值
    }

    @Override
    public long getLastModified() {
        // 返回自定义的lastModified值
        return lastModified;
    }
}

import java.io.IOException;
import java.net.URL;
import java.net.URLConnection;

public class Main {
    public static void main(String[] args) {
        try {
            URL url = new URL("http://example.com");
            URLConnection connection = new ModifiedURLConnection(url);
            connection.connect();
            long lastModified = connection.getLastModified();
            System.out.println("Last Modified: " + lastModified);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}