php截取html字符串自动补全html标签

/**

* 截取HTML,并自动补全闭合

* @param $html

* @param $length

* @param $end

*/

function subHtml($html,$length) {

$result = '';

$tagStack = array();

$len = 0;

$contents = preg_split("~(<[^>]+?>)~si",$html, -1,PREG_SPLIT_NO_EMPTY| PREG_SPLIT_DELIM_CAPTURE);

foreach($contents as $tag)

{

if (trim($tag)=="")continue;

if(preg_match("~<([a-z0-9]+)[^/>]*?/>~si",$tag)){

$result .= $tag;

}else if(preg_match("~</([a-z0-9]+)[^/>]*?>~si",$tag,$match)){

if($tagStack[count($tagStack)-1] == $match[1]){

array_pop($tagStack);

$result .= $tag;

}

}else if(preg_match("~<([a-z0-9]+)[^/>]*?>~si",$tag,$match)){

array_push($tagStack,$match[1]);

$result .= $tag;

}else if(preg_match("~<!--.*?-->~si",$tag)){

$result .= $tag;

}else{

if($len + mstrlen($tag) < $length){

$result .= $tag;

$len += mstrlen($tag);

}else {

$str = msubstr($tag,0,$length-$len+1);

$result .= $str;

break;

}

}

}

while(!empty($tagStack)){

$result .= '</'.array_pop($tagStack).'>';

}

return $result;

}

function msubstr($string, $start, $length,$dot='',$charset = 'UTF-8') {

$string = str_replace(array('&', '"', '<', '>',' '), array('&', '"', '<', '>',' '), $string);

if(strlen($string) <= $length) {

return $string;

}

if(strtolower($charset) == 'utf-8') {

$n = $tn = $noc = 0;

while($n < strlen($string)) {

$t = ord($string[$n]);

if($t == 9 || $t == 10 || (32 <= $t && $t <= 126)) {

$tn = 1; $n++;

} elseif(194 <= $t && $t <= 223) {

$tn = 2; $n += 2;

} elseif(224 <= $t && $t <= 239) {

$tn = 3; $n += 3;

} elseif(240 <= $t && $t <= 247) {

$tn = 4; $n += 4;

} elseif(248 <= $t && $t <= 251) {

$tn = 5; $n += 5;

} elseif($t == 252 || $t == 253) {

$tn = 6; $n += 6;

} else {

$n++;

}

$noc++;

if($noc >= $length) {

break;

}

}

if($noc > $length) {

$n -= $tn;

}

$strcut = substr($string, 0, $n);

} else {

for($i = 0; $i < $length; $i++) {

$strcut .= ord($string[$i]) > 127 ? $string[$i].$string[++$i] : $string[$i];

}

}

return $strcut.$dot;

}

/**

* 取得字符串的长度，包括中英文。

*/

function mstrlen($str,$charset = 'UTF-8'){

if (function_exists('mb_substr')) {

$length=mb_strlen($str,$charset);

} elseif (function_exists('iconv_substr')) {

$length=iconv_strlen($str,$charset);

} else {

preg_match_all("/[x01-x7f]|[xc2-xdf][x80-xbf]|xe0[xa0-xbf][x80-xbf]|[xe1-xef][x80-xbf][x80-xbf]|xf0[x90-xbf][x80-xbf][x80-xbf]|[xf1-xf7][x80-xbf][x80-xbf][x80-xbf]/", $text, $ar);

$length=count($ar[0]);

}

return $length;

}