JSoup -检查某些元素是否有文本，然后只选择一个

Question

我正试图使用JSoup从亚马逊上提取价格，但有两个不同的元素可以提取它。我可以从元素中的aria-label属性中获取它，也可以从元素中的文本中获取它。最好是，我总是希望从aria标签属性中获取它，但有时它并不存在，所以我需要从第二个span类中提取它。我的问题是，如何创建一个if -语句来检查属性，看看它是否有文本，如果没有，则尝试从第二个span类中提取文本？

另外，我试图从名相同的类中获得几个价格，但例如，当我编写doc.select("span.sx-price.sx-price-large").get(0).text()时，什么都不会弹出。

下面是我要从其中一个项提取项的HTML代码：

​

<a class="a-size-small a-link-normal a-text-normal" href="https://rads.stackoverflow.com/amzn/click/B01MZYYWUH">1</a></div>
<div class="a-row a-spacing-mini"><span class="a-size-small a-color-secondary a-text-bold">Product Description</span><br><span class="a-size-small a-color-secondary">... Cards Radeon&trade; <em>RX</em> 460 Graphics Cards Radeon&trade; R9 <em>390</em> Graphics Cards ...</span></div>
</div></div></div></div></div></div></li>
<li id="result_2" data-asin="B00IAAU6SS" class="s-result-item celwidget ">
   <div class="s-item-container">
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   <div class="a-fixed-left-grid-inner" style="padding-left:218px">
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      <div class="a-row">
         <div aria-hidden="true" class="a-column a-span12 a-text-center">
            <a class="a-link-normal a-text-normal" href="https://rads.stackoverflow.com/amzn/click/B00IAAU6SS"><img src="https://images-na.ssl-images-amazon.com/images/I/419c5Ci-UqL._AC_US218_.jpg" srcset="https://images-na.ssl-images-amazon.com/images/I/419c5Ci-UqL._AC_US218_.jpg 1x, https://images-na.ssl-images-amazon.com/images/I/419c5Ci-UqL._AC_US327_FMwebp_QL65_.jpg 1.5x, https://images-na.ssl-images-amazon.com/images/I/419c5Ci-UqL._AC_US436_FMwebp_QL65_.jpg 2x, https://images-na.ssl-images-amazon.com/images/I/419c5Ci-UqL._AC_US500_FMwebp_QL65_.jpg 2.2935x" width="218" height="218" alt="Product Details" class="s-access-image cfMarker" data-search-image-load></a>
            <div class="a-section a-spacing-none a-text-center"></div>
         </div>
      </div>
   </div>
   <div class="a-fixed-left-grid-col a-col-right" style="padding-left:2%;*width:97.6%;float:left;">
   <div class="a-row a-spacing-small">
      <div class="a-row a-spacing-none scx-truncate-medium sx-line-clamp-3 s-list-title-long">
         <a class="a-link-normal s-access-detail-page  s-color-twister-title-link a-text-normal" title="Arctic Accelero Xtreme IV 280(X) - High-End Graphics Card Cooler with Backside Cooler for Efficient RAM and VR-Cooling - DCACO-V930001-GBA01" href="https://rads.stackoverflow.com/amzn/click/B00IAAU6SS">
            <h2 data-attribute="Arctic Accelero Xtreme IV 280(X) - High-End Graphics Card Cooler with Backside Cooler for Efficient RAM and VR-Cooling - DCACO-V930001-GBA01" data-max-rows="3" class="a-size-medium s-inline  s-access-title  a-text-normal">Arctic Accelero Xtreme IV 280(X) - High-End Graphics Card Cooler with Backside Cooler for Efficient RAM and VR-Cooling - DCACO-V930001-GBA01</h2>
         </a>
      </div>
      <div class="a-row a-spacing-none"><span class="a-size-small a-color-secondary">by </span><span class="a-size-small a-color-secondary">ARCTIC</span></div>
   </div>
   <div class="a-row">
   <div class="a-column a-span7">
   <div class="a-row a-spacing-none"><a class="a-link-normal a-text-normal" href="https://rads.stackoverflow.com/amzn/click/B00IAAU6SS"><span aria-label="$85.99" class="a-color-base sx-zero-spacing"><span class="sx-price sx-price-large">
      <sup class="sx-price-currency">$</sup>
      <span class="sx-price-whole">85</span>
      <sup class="sx-price-fractional">99</sup>
      </span>
      </span></a><span class="a-letter-space"></span><i class="a-icon a-icon-prime a-icon-small s-align-text-bottom" aria-label="Prime"><span class="a-icon-alt">Prime</span></i>
   </div>
   <div class="a-row a-spacing-mini">
      <div class="a-row a-spacing-none"><span class="a-size-small a-color-secondary">FREE Shipping on eligible orders</span></div>
      <div class="a-row a-spacing-none"><span class="a-size-small a-color-price">Only 8 left in stock - order soon.</span></div>
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   <div class="a-row a-spacing-mini">
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      <div class="a-row a-spacing-mini"></div>
      <span class="a-size-small a-color-secondary">More Buying Choices</span>
   </div>
   <div class="a-row a-spacing-none">
   <a class="a-size-small a-link-normal a-text-normal" href="https://rads.stackoverflow.com/amzn/click/B00IAAU6SS"><span class="a-color-secondary a-text-strike"></span><span class="a-size-base a-color-base">$85.99</span>

​

Answer 1

我建议使用类.sx-price来选择元素，因为它的名称意味着它包含一个价格。然后您可以选择期望使用aria-label属性的父元素，检查它是否包含使用简单正则表达式的价格-如果为真，直接从该属性获取价格，否则将从嵌套子区间收集数据。

下面你可以找到一个代码，我已经玩过，工作相当好。

final Document doc = Jsoup.parse(html);

final Elements prices = doc.select(".sx-price");

final Pattern pattern = Pattern.compile("^\\$?([0-9]+)\\.([0-9]{2})$");

for (Element el : prices) {
    String price = "";
    if (el.parent().hasAttr("aria-label") && pattern.matcher(el.parent().attr("aria-label")).find()) {
        System.out.println("Extracting price from aria-label...");
        price = el.parent().attr("aria-label");

    } else {
        System.out.println("Extracting price from span body...");
        String currency = el.select(".sx-price-currency").text();
        String whole = el.select(".sx-price-whole").text();
        String fractional = el.select(".sx-price-fractional").text();

        price = String.format("%s%s.%s", currency, !whole.isEmpty() ? whole : "00", !fractional.isEmpty() ? fractional : "00");
    }

    System.out.println(price);
}

希望能帮上忙。

Answer 2

给出你的例子-我们选择span。检查“选择”元素是否为NULL (如果是而不是 NULL )，然后从子span中选择文本。

试试这个(它还没有被我测试过--只是由内存编写的(当然，您需要先获取一个文档，我假设您已经有了))：

try{
 Element span = doc.select("span.a-color-base.sx-zero-spacing").first();

 if(span != null) {
  System.out.println(span.attr("aria-label"));
 } else {
   Element beforeSep = doc.select("span.sx-price-whole").first();
   Element afterSep = doc.select("sup.sx-price-fractional").first();

   System.out.println(beforeSep.text() + "." + afterSep.text());
 }
} catch (Exception ex){
  // exception handler
}