Java HTML/XML - 如何使用jsoup来解析frameset并获取id属性

import java.io.File;

import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;

public class Main {

  public static void main(String[] args) {

    Document doc = Jsoup.parse("html with frame", "UTF-8");
    Document noFramesDoc = Jsoup.parseBodyFragment(doc.select("noframes")
        .text());
    System.out.println("Age = "
        + noFramesDoc.select("input[id=age]").attr("value"));
    System.out.println("Class = "
        + noFramesDoc.select("input[id=class]").attr("value"));

  }

}