DOMDocument in php

Question

DOMDocument in php我刚刚开始阅读有关DOM的文档和示例，以便对文档进行爬行和解析。例如，我有一部分文件如下所示：    <div id="showContent">     <table>     <tr>         <td>          Crap        </td>     </tr><tr>           <td width="172" valign="top"><a href="link"><img height="91" border="0" width="172" class="" src="img"></a></td>           <td width="10">&nbsp;</td>           <td valign="top"><table cellspacing="0" cellpadding="0" border="0">               <tbody><tr>                 <td height="30"><a class="px11" href="link">title</a><a><br>                     <span class="px10"></span>                 </a></td>               </tr>               <tr>                 <td><img height="1" width="580" src="crap"></td>               </tr>               <tr>                 <td align="right">                     <a href="link"><img height="16" border="0" width="65" src="/buy"></a>                 </td>               </tr>               <tr>                 <td valign="top" class="px10">                     <p style="width: 500px;">description.</p>                 </td>               </tr>           </tbody></table></td>         </tr>     <tr>         <td>Crap        </td>     </tr>     <tr>         <td>          Crap        </td>     </tr>     </table>     </div>我试图使用以下代码获取所有tr标记并分析其中是否有垃圾或信息：$dom = new DOMDocument();@$dom->loadHTML($html);$xpath = new DOMXPath($dom);$tags = $xpath->query('.//div[@id="showContent"]');foreach ($tags as $tag) {     $string="";     $string=trim($tag->nodeValue);     if(strlen($string)>3) {         echo $string;         echo '<br>';     }}但是，我只需要去掉没有标记的字符串，例如：CrapCrapTitleDescription但我想知道：<tr>    <td>Crap</td></tr><tr>    <a href="link">title</a></tr>如何保留html节点(标记)？