我需要将html输入剪切到一定长度，同时仍保留标签。总长度必须包含 html 标记。我找不到在最终长度中包含 html 标签长度的解决方案。如何在不破坏标签并确保所有开始标签都有关闭的情况下将 html 输入剪切到一定长度？
基本上，我从用户那里获得 html 输入，我需要使其适合一定的长度。为此，我不想破坏任何 html 标签，但我需要确保总长度(包括标签(小于最大值。
例如，将此字符串剪切为 20 个字符：
<p>this is an example</p>
应给出的输出
<p>this is an ex</p>
这减少了 50 个字符
<p>this <a href="http://example.com">click me</a>jiasd</p>
应该给
<p>this <a href="http://example.com">click</a></p>
我已经尝试过这个解决方案，它适用于将文本剪切到一定长度，但我找不到一种方法来让它计算总数中的标签长度：
function truncateHtml($text, $length = 100, $ending = '...', $exact = false, $considerHtml = true) {
if ($considerHtml) {
// if the plain text is shorter than the maximum length, return the whole text
if (strlen(preg_replace('/<.*?>/', '', $text)) <= $length) {
return $text;
}
// splits all html-tags to scanable lines
preg_match_all('/(<.+?>)?([^<>]*)/s', $text, $lines, PREG_SET_ORDER);
$total_length = strlen($ending);
$open_tags = array();
$truncate = '';
foreach ($lines as $line_matchings) {
// if there is any html-tag in this line, handle it and add it (uncounted) to the output
if (!empty($line_matchings[1])) {
// if it's an "empty element" with or without xhtml-conform closing slash
if (preg_match('/^<('s*.+?'/'s*|'s*(img|br|input|hr|area|base|basefont|col|frame|isindex|link|meta|param)('s.+?)?)>$/is', $line_matchings[1])) {
// do nothing
// if tag is a closing tag
} else if (preg_match('/^<'s*'/([^'s]+?)'s*>$/s', $line_matchings[1], $tag_matchings)) {
// delete tag from $open_tags list
$pos = array_search($tag_matchings[1], $open_tags);
if ($pos !== false) {
unset($open_tags[$pos]);
}
// if tag is an opening tag
} else if (preg_match('/^<'s*([^'s>!]+).*?>$/s', $line_matchings[1], $tag_matchings)) {
// add tag to the beginning of $open_tags list
array_unshift($open_tags, strtolower($tag_matchings[1]));
}
// add html-tag to $truncate'd text
$truncate .= $line_matchings[1];
}
// calculate the length of the plain text part of the line; handle entities as one character
$content_length = strlen(preg_replace('/&[0-9a-z]{2,8};|&#[0-9]{1,7};|[0-9a-f]{1,6};/i', ' ', $line_matchings[2]));
if ($total_length+$content_length> $length) {
// the number of characters which are left
$left = $length - $total_length;
$entities_length = 0;
// search for html entities
if (preg_match_all('/&[0-9a-z]{2,8};|&#[0-9]{1,7};|[0-9a-f]{1,6};/i', $line_matchings[2], $entities, PREG_OFFSET_CAPTURE)) {
// calculate the real length of all entities in the legal range
foreach ($entities[0] as $entity) {
if ($entity[1]+1-$entities_length <= $left) {
$left--;
$entities_length += strlen($entity[0]);
} else {
// no more characters left
break;
}
}
}
$truncate .= substr($line_matchings[2], 0, $left+$entities_length);
// maximum lenght is reached, so get off the loop
break;
} else {
$truncate .= $line_matchings[2];
$total_length += $content_length;
}
// if the maximum length is reached, get off the loop
if($total_length>= $length) {
break;
}
}
} else {
if (strlen($text) <= $length) {
return $text;
} else {
$truncate = substr($text, 0, $length - strlen($ending));
}
}
// if the words shouldn't be cut in the middle...
if (!$exact) {
// ...search the last occurance of a space...
$spacepos = strrpos($truncate, ' ');
if (isset($spacepos)) {
// ...and cut the text in this position
$truncate = substr($truncate, 0, $spacepos);
}
}
// add the defined ending to the text
$truncate .= $ending;
if($considerHtml) {
// close all unclosed html-tags
foreach ($open_tags as $tag) {
$truncate .= '</' . $tag . '>';
}
}
return $truncate;
}
对于正则表达式，在遍历字符时不容易记住长度和出现次数，因此您可以遵循与正则表达式和 DOM 相结合的解决方案(此解决方法主要由 DOM 帮助完成(。
整个哲学是这样的：
1-如果最后一个节点是DOMElement或DOMText：
- 如果通过删除此节点，则总长度将大于限制 ->删除它。
- 如果通过删除此节点，则总长度将小于限制 ->截断。
- 总长度>限制 ？重复 (1(：返回结果。
function truncateHTML($html, $limit = 20) {
static $wrapper = null;
static $wrapperLength = 0;
// trim unwanted CR/LF characters
$html = trim($html);
// Remove HTML comments
$html = preg_replace("~<!--.*?-->~", '', $html);
// If $html in in plain text
if ((strlen(strip_tags($html)) > 0) && strlen(strip_tags($html)) == strlen($html)) {
return substr($html, 0, $limit);
}
// If $html doesn't have a root element
elseif (is_null($wrapper)) {
if (!preg_match("~^'s*<[^'s!?]~", $html)) {
// Defining a tag as our HTML wrapper
$wrapper = 'div';
$htmlWrapper = "<$wrapper></$wrapper>";
$wrapperLength = strlen($htmlWrapper);
$html = preg_replace("~><~", ">$html<", $htmlWrapper);
}
}
// Calculating total length
$totalLength = strlen($html);
// If our input length is less than limit, we are done.
if ($totalLength <= $limit) {
if ($wrapper) {
return preg_replace("~^<$wrapper>|</$wrapper>$~", "", $html);
}
return strlen(strip_tags($html)) > 0 ? $html : '';
}
// Initializing a DOM object to hold our HTML
$dom = new DOMDocument;
$dom->loadHTML($html, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD);
// Initializing a DOMXPath object to query on our DOM
$xpath = new DOMXPath($dom);
// Query last node (this does not include comment or text nodes)
$lastNode = $xpath->query("./*[last()]")->item(0);
// While manipulating, when there is no HTML element left
if ($totalLength > $limit && is_null($lastNode)) {
if (strlen(strip_tags($html)) >= $limit) {
$textNode = $xpath->query("//text()")->item(0);
if ($wrapper) {
$textNode->nodeValue = substr($textNode->nodeValue, 0, $limit );
$html = $dom->saveHTML();
return preg_replace("~^<$wrapper>|</$wrapper>$~", "", $html);
} else {
$lengthAllowed = $limit - ($totalLength - strlen($textNode->nodeValue));
if ($lengthAllowed <= 0) {
return '';
}
$textNode->nodeValue = substr($textNode->nodeValue, 0, $lengthAllowed);
$html = $dom->saveHTML();
return strlen(strip_tags($html)) > 0 ? $html : '';
}
} else {
$textNode = $xpath->query("//text()")->item(0);
$textNode->nodeValue = substr($textNode->nodeValue, 0, -(($totalLength - ($wrapperLength > 0 ? $wrapperLength : 0)) - $limit));
$html = $dom->saveHTML();
return strlen(strip_tags($html)) > 0 ? $html : '';
}
}
// If we have a text node after our last HTML element
elseif ($nextNode = $lastNode->nextSibling) {
if ($nextNode->nodeType === 3 /* DOMText */) {
$nodeLength = strlen($nextNode->nodeValue);
// If by removing our text node total length will be greater than limit
if (($totalLength - ($wrapperLength > 0 ? $wrapperLength : 0)) - $nodeLength >= $limit) {
// We should remove it
$nextNode->parentNode->removeChild($nextNode);
$html = $dom->saveHTML();
return truncateHTML($html, $limit);
}
// If by removing our text node total length will be less than limit
else {
// We should truncate our text to fit the limit
$nextNode->nodeValue = substr($nextNode->nodeValue, 0, ($limit - (($totalLength - ($wrapperLength > 0 ? $wrapperLength : 0)) - $nodeLength)));
$html = $dom->saveHTML();
// Caring about custom wrapper
if ($wrapper) {
return preg_replace("~^<$wrapper>|</$wrapper>$~", "", $html);
}
return $html;
}
}
}
// If current node is an HTML element
elseif ($lastNode->nodeType === 1 /* DOMElement */) {
$nodeLength = strlen($lastNode->nodeValue);
// If by removing current HTML element total length will be greater than limit
if (($totalLength - ($wrapperLength > 0 ? $wrapperLength : 0)) - $nodeLength >= $limit) {
// We should remove it
$lastNode->parentNode->removeChild($lastNode);
$html = $dom->saveHTML();
return truncateHTML($html, $limit);
}
// If by removing current HTML element total length will be less than limit
else {
// We should truncate our node value to fit the limit
$lastNode->nodeValue = substr($lastNode->nodeValue, 0, ($limit - (($totalLength - ($wrapperLength > 0 ? $wrapperLength : 0)) - $nodeLength)));
$html = $dom->saveHTML();
if ($wrapper) {
return preg_replace("~^<$wrapper>|</$wrapper>$~", "", $html);
}
return $html;
}
}
}
例子
1-给出如下所示的输入$limit = 16：
<div>some data from <span class="first">blahblah test</span> was <span class="second">good</span>test<p> something</p><span>letter</span></div>
将生成一个 HTML，此处逐步说明：
Step 0: <div>some data from <span class="first">blahblah test</span> was <span class="second">good</span>test<p> something</p><span>letter</span></div>
Step 1: <div>some data from <span class="first">blahblah test</span> was <span class="second">good</span>test<p> something</p></div>
Step 2: <div>some data from <span class="first">blahblah test</span> was <span class="second">good</span>test</div>
Step 3: <div>some data from <span class="first">blahblah test</span> was <span class="second">good</span></div>
Step 4: <div>some data from <span class="first">blahblah test</span> was </div>
Step 5: <div>some data from <span class="first">blahblah test</span></div>
Step 6: <div>some data from </div>
Step 7: <div>some </div>
2-在您自己的示例中，此输入为$limit = 50：
<p>this <a href="http://example.com">click me</a>jiasd</p>
将输出预期的 HTML：
<p>this <a href="http://example.com">click</a></p>
3-纯文本的处理方式相同($limit = 10(：
Hi how are you doing?
输出：
Hi how are
4- 包括HTML注释($limit = 10(：
<div>some data from <span class="first">blahblah test</span> was <span class="second">good</span>test<p> something</p><span class="text">hola</span><!-- comment --></div>
输出：
string(0) ""
为什么是空的？因为当函数最后但一步时，它会看到长度为 11 的<div></div>。我们无法对它做任何事情，所以我们完全删除了它。
5-最后一个带有$limit = 12的示例的输出：
<div>s</div>
PHP现场演示
您应该从截断的字符串中提取 HTML 标记。然后计算这些字符并再次截断字符串的纯文本部分。
请注意，以下正则表达式将所有 html 标签与所有属性(开始和结束标签(匹配。
在结束return $truncate;之前：
preg_match_all('/<[^>]+>/', $truncate, $html_tags);
$html_tags_length = strlen(implode('', $html_tags));
此时，您可以提取字符串的文本部分并将其切断，也可以递归调用您的函数。
这有点启发式，但它应该有效。
function truncateHtml($text, $length = 100) {
$current_size = strlen($text);
$diff = strlen($text);
$remainder = $current_size - $length;
while($diff > 0 AND $remainder > 0) {
$pattern = "/(.*)[^<>](?=<)/s";
$text = preg_replace($pattern, "$1", $text);
$diff = $current_size - strlen($text);
$current_size = strlen($text);
$remainder = $current_size - $length;
}
// iff $diff == 0 there are no more characters to remove
// iff $remainder == 0 there should removed no more characters
return $text;
}
这里是运行代码。
您可以通过正则表达式实现拆分并仅计算不属于标签的字符。
例：
<?php
function htmlTrim($inStr, $length) {
$c = 0;
$outStr = preg_replace_callback(
"/<.*?>|[^<>]*/",
function($str) use (& $c, $length){
$str = $str[0];
if ($str && $str[0] == "<") { // Is tag.
return $str;
} else {
if ($c >= $length) return ""; // Lenght already exceeded.
$l = strlen($str);
$c += $l;
$overflow = $c - $length;
if ($overflow > 0) {
return substr($str, 0, $l - $overflow);
} else {
return $str;
}
};
},
$inStr
);
return $outStr;
};
echo htmlTrim("<span>Hello <b>World foobar</b></span>", 11);