我遇到的最佳解决方案来自 CakePHP 框架 TextHelper 类
这是方法
/**
* Truncates text.
*
* Cuts a string to the length of $length and replaces the last characters
* with the ending if the text is longer than length.
*
* ### Options:
*
* - `ending` Will be used as Ending and appended to the trimmed string
* - `exact` If false, $text will not be cut mid-word
* - `html` If true, HTML tags would be handled correctly
*
* @param string $text String to truncate.
* @param integer $length Length of returned string, including ellipsis.
* @param array $options An array of html attributes and options.
* @return string Trimmed string.
* @access public
* @link http://book.cakephp.org/view/1469/Text#truncate-1625
*/
function truncate($text, $length = 100, $options = array()) {
$default = array(
'ending' => '...', 'exact' => true, 'html' => false
);
$options = array_merge($default, $options);
extract($options);
if ($html) {
if (mb_strlen(preg_replace('/<.*?>/', '', $text)) <= $length) {
return $text;
}
$totalLength = mb_strlen(strip_tags($ending));
$openTags = array();
$truncate = '';
preg_match_all('/(<\/?([\w+]+)[^>]*>)?([^<>]*)/', $text, $tags, PREG_SET_ORDER);
foreach ($tags as $tag) {
if (!preg_match('/img|br|input|hr|area|base|basefont|col|frame|isindex|link|meta|param/s', $tag[2])) {
if (preg_match('/<[\w]+[^>]*>/s', $tag[0])) {
array_unshift($openTags, $tag[2]);
} else if (preg_match('/<\/([\w]+)[^>]*>/s', $tag[0], $closeTag)) {
$pos = array_search($closeTag[1], $openTags);
if ($pos !== false) {
array_splice($openTags, $pos, 1);
}
}
}
$truncate .= $tag[1];
$contentLength = mb_strlen(preg_replace('/&[0-9a-z]{2,8};|&#[0-9]{1,7};|&#x[0-9a-f]{1,6};/i', ' ', $tag[3]));
if ($contentLength + $totalLength > $length) {
$left = $length - $totalLength;
$entitiesLength = 0;
if (preg_match_all('/&[0-9a-z]{2,8};|&#[0-9]{1,7};|&#x[0-9a-f]{1,6};/i', $tag[3], $entities, PREG_OFFSET_CAPTURE)) {
foreach ($entities[0] as $entity) {
if ($entity[1] + 1 - $entitiesLength <= $left) {
$left--;
$entitiesLength += mb_strlen($entity[0]);
} else {
break;
}
}
}
$truncate .= mb_substr($tag[3], 0 , $left + $entitiesLength);
break;
} else {
$truncate .= $tag[3];
$totalLength += $contentLength;
}
if ($totalLength >= $length) {
break;
}
}
} else {
if (mb_strlen($text) <= $length) {
return $text;
} else {
$truncate = mb_substr($text, 0, $length - mb_strlen($ending));
}
}
if (!$exact) {
$spacepos = mb_strrpos($truncate, ' ');
if (isset($spacepos)) {
if ($html) {
$bits = mb_substr($truncate, $spacepos);
preg_match_all('/<\/([a-z]+)>/', $bits, $droppedTags, PREG_SET_ORDER);
if (!empty($droppedTags)) {
foreach ($droppedTags as $closingTag) {
if (!in_array($closingTag[1], $openTags)) {
array_unshift($openTags, $closingTag[1]);
}
}
}
}
$truncate = mb_substr($truncate, 0, $spacepos);
}
}
$truncate .= $ending;
if ($html) {
foreach ($openTags as $tag) {
$truncate .= '</'.$tag.'>';
}
}
return $truncate;
}
其他框架可能对此问题有类似（或不同）的解决方案，因此您也可以查看它们。我对 Cake 的熟悉促使我链接到他们的解决方案
编辑：
刚刚在我正在使用 OP 文本的应用程序中测试了这种方法
<?php
echo truncate(
'Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. <strong>Stet clita kasd gubergren</strong>',
236,
array('html' => true, 'ending' => ''));
?>
输出：
Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. <strong>Stet clita kasd gubegre</strong>
请注意，输出在完成最后一个单词之前停止，但包含完整的强标签
