提取内部元素而不循环 [英] Extract inner element without looping

问题描述

如果我遍历所有 ，并在第一个之后立即中断，请从以下示例HTML代码中提取href值：

 < li class =parts partname parts_first> 
< div id =dpdn10uri =/ public / page / part1class =partype partstate> 
< div class =ptctainer> 
< div class =ptitle> 
< p class =ptypead> 
< span class =rtext>< a href =http://www.example.com/page/ptname.html?dv=rfirstclass =mnLabel> First<一个>< /跨度> 
< span class =ndx> 
< a href =＃dndx =dpdn10class =xpnd _tstyle =opacity：1>详情：< / a> 
< / span> 
< / p> 
< / div> 
< / div> 
 
< div id =dpdn10_contentclass =xpns> 
< div class =ptctainer> 
< div class =ptitle> 
< p class =ptypead> 
< span class =rtext>< a href =http://www.example.com/page/ptname.html?dv=rfirstclass =mnLabel> First<一个>< /跨度> 
< span class =ndx>< a href =＃class =xpnd>详情：< / a>< / span> 
< / p> 
< / div> 
< / div> 
< / div> 
< / div> 
< / li> 
  

当我可以假设href值对于 ，如上面的例子。

但是，如果这些方法不相同，并且我想提取特定的一个（第一个或第二个）。

这让我在Jsoup中寻找一个允许嵌套选择的机制：直到现在我已经熟悉单层选择，如下所示：

/ p>

 元素链接= doc.select（a [href]）; // a with href 
元素pngs = doc.select（img [src $ =。png]）; // img with src ending .png 
 Element masthead = doc.select（div.masthead）。first（）; // div with class = masthead 
  

但是我找不到多层次的文档或示例选择，例如

 元素链接= doc.select（div.xpns.div.ptctainer.div.ptitle.p.ptypead .span.rtext）; 
  

当然，以上仅用于说明而非实际的语法。我不知道在Jsoup中是否有这样的可能（还）。

Jsoup中存在这种嵌套选择吗？

解决方案

你难道不能'链接'选择功能吗？喜欢：

 元素链接= doc.select（div.xpns）。select（div.ptctainer）。select （ div.ptitle）选择（ p.ptypead）选择（ span.rtext）; 
  

Extracting the href value from the following sample HTML code is straight forward if I loop through all and break immediately after the first one:

  <li class="parts partname parts_first">
    <div id="dpdn10" uri="/public/page/part1" class="partype partstate">
      <div class="ptctainer">
        <div class="ptitle">
          <p class="ptypead">
            <span class="rtext"><a href="http://www.example.com/page/ptname.html?dv=rfirst" class="mnLabel">First</a></span>
            <span class="ndx">
              <a href="#" dndx="dpdn10" class="xpnd _t" style="opacity:1">Details: </a>
            </span>
          </p>
        </div>
      </div>

      <div id="dpdn10_content" class="xpns">
        <div class="ptctainer">
          <div class="ptitle">
            <p class="ptypead">
              <span class="rtext"><a href="http://www.example.com/page/ptname.html?dv=rfirst" class="mnLabel">First</a></span>
              <span class="ndx"><a href="#" class="xpnd">Details: </a></span>
            </p>
          </div>
        </div>    
      </div>
    </div>
  </li>

I can certainly do that when I can assume the href value is identical for both instances of as in the example above.

However, this approach fails if they are not identical and I want to extract a specific one (either the first or the second).

Which brings me to searching for a mechanism in Jsoup that allows "nested selection": Up until now I have been familiar with single-level selection as in:

Elements links = doc.select("a[href]"); // a with href
Elements pngs = doc.select("img[src$=.png]");  // img with src ending .png
Element masthead = doc.select("div.masthead").first();  // div with class=masthead

But I can't find documentation or an example for multi-level selection, e.g.

Element link= doc.select("div.xpns.div.ptctainer.div.ptitle.p.ptypead.span.rtext");

The above is for illustration and not real syntax, of course. I don't know if something like this is possible (yet) in Jsoup.

Does such "nested selection" exist in Jsoup?

解决方案

Can't you just 'chain' the selection functions? Like:

Element link = doc.select("div.xpns").select("div.ptctainer").select("div.ptitle").select("p.ptypead").select("span.rtext");

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