php里的html内容切取

HTMl内容的切取，找了很多都不行或有乱码，然后我组合了一个。

/**
    * 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.
    *
    * @param string  $text String to truncate.
    * @param integer $length Length of returned string, including ellipsis.
    * @param string  $ending Ending to be appended to the trimmed string.
    * @param boolean $exact If false, $text will not be cut mid-word
    * @param boolean $considerHtml If true, HTML tags would be handled correctly
    * @return string Trimmed string.
    */
    function truncate($text, $length = 100, $ending = '...', $exact = true, $considerHtml = false) {
        if ($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 (f.e. <br/>)
                    if (preg_match('/^<(\s*.+?\/\s*|\s*(img|br|input|hr|area|base|basefont|col|frame|isindex|link|meta|param)(\s.+?)?)>$/is', $line_matchings[1])) {
                        // do nothing
                    // if tag is a closing tag (f.e. </b>)
                    } else if (preg_match('/^<\s*\/([^\s]+?)\s*>$/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 (f.e. <b>)
                    } 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};|&#x[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};|&#x[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);
                    
                    $truncate .= cutString($line_matchings[2], $left+$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));
                $truncate = cutString($text,$length - strlen($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);
                $truncate = cutString($truncate,$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;
       
    }

    private function cutString($sourcestr,$cutlength) 
    { 
       $returnstr=''; 
       $i=0; 
       $n=0; 
       $str_length=strlen($sourcestr);//字符串的字节数 
       while (($n<$cutlength) and ($i<=$str_length)) 
       { 
          $temp_str=substr($sourcestr,$i,1); 
          $ascnum=Ord($temp_str);//得到字符串中第$i位字符的ascii码 
          if ($ascnum>=224)    //如果ASCII位高与224，
          { 
             $returnstr=$returnstr.substr($sourcestr,$i,3); //根据UTF-8编码规范，将3个连续的字符计为单个字符         
             $i=$i+3;            //实际Byte计为3
             $n++;            //字串长度计1
          }
          elseif ($ascnum>=192) //如果ASCII位高与192，
          { 
             $returnstr=$returnstr.substr($sourcestr,$i,2); //根据UTF-8编码规范，将2个连续的字符计为单个字符 
             $i=$i+2;            //实际Byte计为2
             $n++;            //字串长度计1
          }
          elseif ($ascnum>=65 && $ascnum<=90) //如果是大写字母，
          { 
             $returnstr=$returnstr.substr($sourcestr,$i,1); 
             $i=$i+1;            //实际的Byte数仍计1个
             $n++;            //但考虑整体美观，大写字母计成一个高位字符
          }
          else                //其他情况下，包括小写字母和半角标点符号，
          { 
             $returnstr=$returnstr.substr($sourcestr,$i,1); 
             $i=$i+1;            //实际的Byte数计1个
             $n=$n+0.5;        //小写字母和半角标点等与半个高位字符宽...
          } 
       } 
         
         //if ($str_length>$cutlength){
         //     $returnstr = $returnstr . "...";//超过长度时在尾处加上省略号
          //}
        return $returnstr;  
    }

2个都是网上找的然后组合的。呵呵

使用：

echo self::truncate($str,146,'...',true,true);

好像这个也不错：http://code.google.com/p/cut-html-string/ 

不过我测试有问题，可能是测试问题。