使用Jsoup解析页面时如何获取JavaScript生成的内容

Question

I want to get this value selected in the picture 1, but it's generated after one second of the page loading

This is what I actually get when I use jsoup

String form_build_id =newAppDoc.select("input[name=form_build_id]").first().attr("value");  
System.out.println(form_build_id);

String form_token = newAppDoc.select("input[name=form_token]").first().attr("value"); 
System.out.println(form_token);

String form_id = newAppDoc.select("input[name=form_id]").first().attr("value"); 
System.out.println(form_id);`][2]

任何想法。