如何把mht文件转化为html文件?

Question

用tp5把mht文件转化为html文件.暂时不使用工具.
<?php

    /**
    * 针对Mht格式的文件进行解析
    * 使用例子:
    * 
    * function mhtmlParseBody($filename) {
    
    if (file_exists ( $filename )) {
    if (is_dir ( $filename )) return false;
    
    $filename = strtolower ( $filename );
    if (strpos ( $filename, '.mht', 1 ) == FALSE) return false;
    
    
    $o_mhtml = new mhtml ();
    $o_mhtml->set_file ( $filename );
    $o_mhtml->extract ();
    return $o_mhtml->get_part_to_file(0);
    
    }
    return null;
    }
    
    function mhtmlParseAll($filename) {
    
    if (file_exists ( $filename )) {
    if (is_dir ( $filename )) return false;
    
    $filename = strtolower ( $filename );
    if (strpos ( $filename, '.mht', 1 ) == FALSE) return false;
    
    
    $o_mhtml = new mhtml ();
    $o_mhtml->set_file ( $filename );
    $o_mhtml->extract ();
    return $o_mhtml->get_all_part_file();
    
    }
    return null;
    }
    */
    
    class mhtparse {
    
    var $file = '';
    var $boundary = '';
    var $filedata = '';
    var $countparts = 1;
    var $log = '';
    
    function extract() {
    $this->read_filedata ();
    $this->file_parts ();
    
    return 1;
    }
    
    function set_file($p) {
    $this->file = $p;
    }
    
    function get_log() {
    return $this->log;
    }
    
    function file_parts() {
    $lines = explode ( "n", substr ( $this->filedata, 0, 8192 ) );
    foreach ( $lines as $line ) {
    $line = trim ( $line );
    if (strpos ( $line, '=' ) !== FALSE) {
    if (strpos ( $line, 'boundary', 0 ) !== FALSE) {
    $range = $this->getrange ( $line, '"', '"', 0 );
    $this->boundary = "--" . $range ['range'];
    $this->filedata = str_replace ( $line, '', $this->filedata );
    break;
    }
    }
    }
    if ($this->boundary != '') {
    $this->filedata = explode ( $this->boundary, $this->filedata );
    unset ( $this->filedata [0] );
    $this->filedata = array_values ( $this->filedata );
    $this->countparts = count ( $this->filedata );
    } else {
    $tmp = $this->filedata;
    $this->filedata = array (
    $tmp 
    );
    }
    }
    
    function get_all_part_file() {
    return $this->filedata;
    }
    
    function get_part_to_file($i) {
    $line_data_start = 0;
    $encoding = '';
    $part_lines = explode ( "n", ltrim ( $this->filedata [$i] ) );
    foreach ( $part_lines as $line_id => $line ) {
    $line = trim ( $line );
    if ($line == '') {
    if (trim ( $part_lines [0] ) == '--')
    return 1;
    $line_data_start = $line_id;
    break;
    }
    if (strpos ( $line, ':' ) !== FALSE) {
    $pos = strpos ( $line, ':' );
    $k = strtolower ( trim ( substr ( $line, 0, $pos ) ) );
    $v = trim ( substr ( $line, $pos + 1, strlen ( $line ) ) );
    if ($k == 'content-transfer-encoding') {
    $encoding = $v;
    }
    if ($k == 'content-location') {
    $location = $v;
    }
    if ($k == 'content-type') {
    $contenttype = $v;
    }
    }
    }
    
    foreach ( $part_lines as $line_id => $line ) {
    if ($line_id <= $line_data_start)
    $part_lines [$line_id] = '';
    }
    
    $part_lines = implode ( '', $part_lines );
    if ($encoding == 'base64')
    $part_lines = base64_decode ( $part_lines );
    elseif ($encoding == 'quoted-printable')
    $part_lines = imap_qprint ( $part_lines );
    
    return $part_lines;
    }
    
    function read_filedata() {
    $handle = fopen ( $this->file, 'r' );
    $this->filedata = fread ( $handle, filesize ( $this->file ) );
    fclose ( $handle );
    }
    
    function getrange(&$subject, $Beginmark_str = '{', $Endmark_str = '}', $Start_pos = 0) {
    /*
    * $str="sssss { x { xx } {xx{xx } x} x} sssss"; $range=string::getRange($str,'{','}',0); echo $range['range']; //tulem: " x { xx } {xx{xx } x} x" echo $range['behin']; //tulem: 6 echo $range['end']; //tulem: 30 (' ') -- l5pumärgist järgnev out: array('range'=>$Range,'begin'=>$Begin_firstOccurence_pos,'end'=>$End_sequel_pos) | false v1.1 2004-2006,Uku-Kaarel J5esaar,[email protected],http://www.hot.ee/ukjoesaar,[phone]
    */
    if (empty ( $Beginmark_str ))
    $Beginmark_str = '{';
    $Beginmark_str_len = strlen ( $Beginmark_str );
    
    if (empty ( $Endmark_str ))
    $Endmark_str = '}';
    $Endmark_str_len = strlen ( $Endmark_str );
    
    /* $Start_pos_cache = 0; */
    do {
    /* !algus */
    if (! is_int ( $Begin_firstOccurence_pos ))
    $Start_pos_cache = $Start_pos;
    
    /* ?algus-test */
    $Start_pos_cache = @strpos ( $subject, $Beginmark_str, $Start_pos_cache );
    
    /* this is possible start for range */
    if (is_int ( $Start_pos_cache )) {
    /* skip */
    $Start_pos_cache = ($Start_pos_cache + $Beginmark_str_len);
    /* test possible range start pos */
    if (is_int ( $Begin_firstOccurence_pos )) {
    if ($Start_pos_cache < $range_end_pos)
    $rangeClean = 0;
    elseif ($Start_pos_cache > $range_end_pos)
    $rangeClean = 1;
    }
    /* here it is */
    if (! is_int ( $Begin_firstOccurence_pos ))
    $Begin_firstOccurence_pos = $Start_pos_cache;
    } /* VIGA NR 0 ALGUST EI OLE */
    
    if (! is_int ( $Start_pos_cache )) {
    /* !algus */
    /* VIGA NR 1 ALGUSMARKI EI LEITUD : VIIMANE VOIMALIK ALGUS */
    if (is_int ( $Begin_firstOccurence_pos ) and ($Start_pos_cache < $range_end_pos))
    $rangeClean = 1;
    else
    return false;
    }
    if (is_int ( $Begin_firstOccurence_pos ) and ($rangeClean != 1)) {
    if (! is_int ( $End_pos_cache ))
    $End_sequel_pos = $Begin_firstOccurence_pos;
    
    $End_pos_cache = strpos ( $subject, $Endmark_str, $End_sequel_pos );
    
    /* ok */
    if (is_int ( $End_pos_cache ) and ($rangeClean != 1)) {
    $range_current_lenght = ($End_pos_cache - $Begin_firstOccurence_pos);
    $End_sequel_pos = ($End_pos_cache + $Endmark_str_len);
    $range_end_pos = $End_pos_cache;
    }
    /* VIGA NR 2 LOPPU EI LEITUD */
    if (! is_int ( $End_pos_cache ))
    if ($End_pos_cache == false)
    return false;
    }
    } while ( $rangeClean < 1 );
    
    if (is_int ( $Begin_firstOccurence_pos ) and is_int ( $range_current_lenght ))
    $Range = substr ( $subject, $Begin_firstOccurence_pos, $range_current_lenght );
    else
    return false;
    
    return array (
    'range' => $Range,
    'begin' => $Begin_firstOccurence_pos,
    'end' => $End_sequel_pos 
    );
    } // end getrange()
    } // class
    ?>
    上面的代码出自https://yq.aliyun.com/php/9381,没有看懂是怎么玩的,求大神们指点.