从仅保留其中一个的字符串中删除所有html标签。 具有一个标识符属性的高级strip_tags

Question

我需要删除一个字符串中的HTML标签，并仅保留其中一种类型。 我有一个包含此的字符串：

 <!-- comment -->   <div id="55"> text </div> <span name=annotation value=125> 2 text </span> <p id="55"> text 3</p><span>text 4 <span>

我需要这个：

text  <span name=annotation value=125> 2 text </span> text 3text4

因此，我需要删除所有HTML标记（具有这种形式的标记除外）

"/(<span[^>]*annotation[^>]*value=.?(\w*).?[^>]*>)(.*?)<\/span>/"

我用它作为另一种表达的一部分，但得到了一个主意

我怎样才能做到这一点？

我知道可以用preg_replace() ，但是我不知道我需要什么模式。

一个例子：

$str='<!-- comment --><p><b>Deoxyribonucleic acid</b> (<b>DNA</b>) is 
   a molecule encoding the <a href="/wiki/Genetics" title="Genetics">genetic</a> instructions
   used in the development and functioning of all known living <a href="/wiki/Organism" title="Organism">organi
   sms</a> and many <a href="/wiki/Virus" title="Virus">viruses</a>. Along with <a href="/wiki/RNA" title="RNA">RNA</a> and <a href="/wiki/Proteins" title="Proteins" class="mw-redirect">proteins</a>, DNA is one of the three major 
   <a href="/wiki/Macromolecules" title="Macromolecules" class="mw-redirect">macromolecules</a> 
   that are essential for all known forms of <a href="/wiki/Life" title="Life">life</a>.
   Genetic information is encoded<span id="200120131815150" 
   class="mymetastasis" value="247" name="annotation"> as a sequence of nucleotides (</span><a href="/wiki/Guanine" title="Guanine"><span id="200120131815151" class="mymetastasis" value="247" name="annotation">
   guanine</span></a><span id="200120131815152" class="mymetastasis" value="247" name="annotation">, </span><a href="/wiki/Adenine" title="Adenine"><span id="200120131815153" class="mymetastasis" value="247"
   name="annotation">adenine</span></a><span id="200120131815154" class="mymetastasis" value="247" name="annotation">,
   </span><a href="/wiki/Thymine" title="Thymine"><span id="200120131815155" class="mymetastasis" value="247"
   name="annotation">thymine</span></a><span id="200120131815156" class="mymetastasis" value="247" name="annotation">, 
   and </span><a href="/wiki/Cytosine" title="Cytosine">
   <span id="200120131815157" class="mymetastasis" value="247" name="annotation">cytosine</span></a><span id="200120131815158" class="mymetastasis" value="247" name="annotation">) 
   recorded using the letters G, A, T, and C. Most DNA molecules are double-strande</span>d helices, consisting of two long <a href="/wiki/Polymers" title="Polymers" class="mw-redirect">polymers</a> of simple units called <a href="/wiki/Nucleotide" 
   title="Nucleotide">nucleotides</a>, molecules with <a href="/wiki/Backbone_chain" title="Backbone chain">backbones</a>
   made of alternating <a href="/wiki/Monosaccharide" title="Monosaccharide">sugars<
   /a> (<a href="/wiki/Deoxyribose" title="Deoxyribose">deoxyribose</a>) and <a href="/wiki/Phosphate"
   title="Phosphate">phosphate</a> groups (related to phosphoric acid), with the <a href="/wiki/Nucleobases" title="Nucleobases" class="mw-redirect">nucleobases</a> (G, A, T, C) attached to the sugars. DNA is well-suited for biological information storage, since the DNA backbone is resistant to cleavage and the double-stranded structure provides the molecule with a 
   built-in duplicate of the encoded information.</p>';

PD：换行，制表符等是无意的。 源文本的一部分。

Answer 1

您将需要多个regex来执行此操作。

工作代码：

<?php
    header("Content-Type: text/plain");

    $str = '<!-- comment -->   <div id="55"> text </div> <span name=annotation value=125> 2 text </span> <p id="55"> text 3</p><span>text 4 </span>';

    // Save needed values
    $str = preg_replace("/<(span[^>]*?annotation.*?)>(.*?)<\/(.*?)>/", "!!!$1!!!$2!!!$3!!!", $str); 

    // Remove everything else
    $re = "/(<[^>]*?>)/";
    $str = preg_replace($re, "", $str);

    // Restore
    $str = preg_replace("/\!\!\!(span[^>]*?annotation.*?)\!\!\!(.*?)\!\!\!(.*?)\!\!\!/", "<$1>$2</$3>", $str); 

    echo $str;
?>

输出：

text  <span name=annotation value=125> 2 text </span>  text 3text 4 

---

输入：

$str='<!-- comment --><p><b>Deoxyribonucleic acid</b> (<b>DNA</b>) is 
   a molecule encoding the <a href="/wiki/Genetics" title="Genetics">genetic</a> instructions
   used in the development and functioning of all known living <a href="/wiki/Organism" title="Organism">organi
   sms</a> and many <a href="/wiki/Virus" title="Virus">viruses</a>. Along with <a href="/wiki/RNA" title="RNA">RNA</a> and <a href="/wiki/Proteins" title="Proteins" class="mw-redirect">proteins</a>, DNA is one of the three major 
   <a href="/wiki/Macromolecules" title="Macromolecules" class="mw-redirect">macromolecules</a> 
   that are essential for all known forms of <a href="/wiki/Life" title="Life">life</a>.
   Genetic information is encoded<span id="200120131815150" 
   class="mymetastasis" value="247" name="annotation"> as a sequence of nucleotides (</span><a href="/wiki/Guanine" title="Guanine"><span id="200120131815151" class="mymetastasis" value="247" name="annotation">
   guanine</span></a><span id="200120131815152" class="mymetastasis" value="247" name="annotation">, </span><a href="/wiki/Adenine" title="Adenine"><span id="200120131815153" class="mymetastasis" value="247"
   name="annotation">adenine</span></a><span id="200120131815154" class="mymetastasis" value="247" name="annotation">,
   </span><a href="/wiki/Thymine" title="Thymine"><span id="200120131815155" class="mymetastasis" value="247"
   name="annotation">thymine</span></a><span id="200120131815156" class="mymetastasis" value="247" name="annotation">, 
   and </span><a href="/wiki/Cytosine" title="Cytosine">
   <span id="200120131815157" class="mymetastasis" value="247" name="annotation">cytosine</span></a><span id="200120131815158" class="mymetastasis" value="247" name="annotation">) 
   recorded using the letters G, A, T, and C. Most DNA molecules are double-strande</span>d helices, consisting of two long <a href="/wiki/Polymers" title="Polymers" class="mw-redirect">polymers</a> of simple units called <a href="/wiki/Nucleotide" 
   title="Nucleotide">nucleotides</a>, molecules with <a href="/wiki/Backbone_chain" title="Backbone chain">backbones</a>
   made of alternating <a href="/wiki/Monosaccharide" title="Monosaccharide">sugars<
   /a> (<a href="/wiki/Deoxyribose" title="Deoxyribose">deoxyribose</a>) and <a href="/wiki/Phosphate"
   title="Phosphate">phosphate</a> groups (related to phosphoric acid), with the <a href="/wiki/Nucleobases" title="Nucleobases" class="mw-redirect">nucleobases</a> (G, A, T, C) attached to the sugars. DNA is well-suited for biological information storage, since the DNA backbone is resistant to cleavage and the double-stranded structure provides the molecule with a 
   built-in duplicate of the encoded information.</p>';

输出：

Deoxyribonucleic acid (DNA) is 
   a molecule encoding the genetic instructions
   used in the development and functioning of all known living organi
   sms and many viruses. Along with RNA and proteins, DNA is one of the three major 
   macromolecules 
   that are essential for all known forms of life.
   Genetic information is encoded<span id="200120131815150" 
   class="mymetastasis" value="247" name="annotation"> as a sequence of nucleotides (</span>
   guanine<span id="200120131815152" class="mymetastasis" value="247" name="annotation">, </span><span id="200120131815153" class="mymetastasis" value="247"
   name="annotation">adenine</span>,
   <span id="200120131815155" class="mymetastasis" value="247"
   name="annotation">thymine</span>, 
   and 
   <span id="200120131815157" class="mymetastasis" value="247" name="annotation">cytosine</span>) 
   recorded using the letters G, A, T, and C. Most DNA molecules are double-stranded helices, consisting of two long polymers of simple units called nucleotides, molecules with backbones
   made of alternating sugars (deoxyribose) and phosphate groups (related to phosphoric acid), with the nucleobases (G, A, T, C) attached to the sugars. DNA is well-suited for biological information storage, since the DNA backbone is resistant to cleavage and the double-stranded structure provides the molecule with a 
   built-in duplicate of the encoded information.

Answer 2

PHP为此有一个内置功能，称为strip_tags

如果只想保留span标签，请使用第二个参数。

所以，

$cleanString = strip_tags($dirtyString, '<span>');