如何解析CNBC Markets Page中的表格数据？

Question

我有一个我正在编写的程序，它接受用户输入连接到一个网站，下载它的html为文本，并从表中检索数据，一天两次。我明白代码不会是一个大小适合所有的页面(我可能会“硬”的网址到代码，一旦我得到它的工作)。我目前的问题是，我的jsoup解析器不能正确地读取表格数据。我不确定我的元素选择器是不是太通用了？该表看起来像是标准的table/tr/td格式，但是我的行数组填充的大小为0。如果有人能帮我调试我的解析器，并可能提供一些建议，让它一天两次静默地抓取数据，我会非常感激！没有运行时/编译错误，只需要更正输出。

源站点:表(代码片段)的https://www.cnbc.com/us-markets/源代码：

<table class="BasicTable-table"><thead class="BasicTable-tableHeading BasicTable-tableHeadingSortable"><tr><th class="BasicTable-textData"><span>SYMBOL <span class="icon-sort undefined"></span></span></th><th class="BasicTable-numData"><span>PRICE <span class="icon-sort undefined"></span></span></th><th class="BasicTable-numData">

我的代码：

public class StockScraper {

public static void main(String[] args) {
    Scanner input = new Scanner (System.in);
    System.out.println("Enter the complete url (including http://) of the site you would like to parse:");
    String html = input.nextLine();
    try {
        Document doc = Jsoup.connect(html).get();
        System.out.printf("Title: %s", doc.title());
        //Try to print site content
        System.out.println("");
        System.out.println("Writing html contents to 'html.txt'...");
        //Save html contents to text file
        PrintWriter outputfile = new PrintWriter("html.txt");
        outputfile.print(doc.outerHtml());
        outputfile.close();

        //Select stock data you want to retrieve
        System.out.println("Enter the name of the stock you want to check");
        String name = input.nextLine();

        //Pull data from CNBC Markets
        Element table = doc.select("table").get(0);
        Elements rows = table.select("tr");
        System.out.println(rows.size());
        for(int i = 1; i < rows.size(); i++) {
            Element rowx = rows.get(i);
            Elements col = rows.select("td");
            if(col.get(0).equals(name)) {
                System.out.println("I worked!");
                System.out.println(col.get(1));
            }
        }
} catch (IOException e) {
        e.printStackTrace();
    }
}

Answer 1

这里的问题是，这个站点是一个动态页面，它在浏览器最初下载页面之后加载内容。Jsoup不足以抓取这样的页面。您有以下几个选项：

1)使用模拟浏览器的工具，并执行所有必要的api调用。有几个选项是Selenium WebDriver或HTMLUnit。

2)找出你在这个站点上感兴趣的api调用，然后直接调用这些api就可以得到一个可以解析的JSON文档。您可以通过在浏览器中打开开发人员工具，然后查看网络选项卡来查看api详细信息。对于此站点，下面是一个示例，其中包括DJI的股票报价：

https://quote.cnbc.com/quote-html-webservice/quote.htm?noform=1&partnerId=2&fund=1&exthrs=0&output=json&symbolType=issue&symbols=599362|579435|593933|49020635|49031016|5093160|617254|601065&requestMethod=extended

Returns:

ExtendedQuoteResult: {
  xmlns: "http://quote.cnbc.com/services/MultiQuote/2006",
  ExtendedQuote: [{
    QuickQuote: {
      symbol: ".DJI",
      code: "0",
      curmktstatus: "REG_MKT",
      FundamentalData: {
      yrlodate: "2020-03-23",
      yrloprice: "18213.65",
      yrhidate: "2020-02-12",
      yrhiprice: "29568.57"
    },
    mappedSymbol: {
      xsi:nil: "true"
    },
    source: "Exchange",
    cnbcId: "599362",
    prev_prev_closing: "21413.44",
    high: "22783.45",
    low: "21693.63",
    provider: "CNBC Quote Cache",
    streamable: "0",
    last_time: "2020-04-06T17:16:28.000-0400",
    countryCode: "US",
    previous_day_closing: "21052.53",
    altName: "Dow Industrials",
    reg_last_time: "2020-04-06T17:16:28.000-0400",
    last_time_msec: "1586207788000",
    altSymbol: ".DJI",
    change_pct: "7.73",
    providerSymbol: ".DJI",
    assetSubType: "Index",
    comments: "RIC",
    last: "22679.99",
    issue_id: "599362",
    cacheServed: "false",
    responseTime: "Mon Apr 06 19:12:09 EDT 2020",
    change: "1627.46",
    timeZone: "EDT",
    onAirName: "Dow Industrials",
    symbolType: "issue",
    assetType: "INDEX",
    volume: "614200990",
    fullVolume: "614200990",
    realTime: "true",
    name: "Dow Jones Industrial Average",
    quoteDesc: { },
    exchange: "Dow Jones Global Indexes",
    shortName: "DJIA",
    cachedTime: "Mon Apr 06 19:12:09 EDT 2020",
    currencyCode: "USD",
    open: "21693.63"
  }
}
...