最好的邮件编码解码类

function build_text_body($body) {
        return "\n<pre>".$this->make_link_clickable($this->linesize(htmlspecialchars($body),85))."</pre>\n";
    }

    function decode_qp($text) {
        $text = quoted_printable_decode($text);
        /*
        $text = str_replace("\r","",$text);
        $text = ereg_replace("=\n", "", $text);
        $text = str_replace("\n","\r\n",$text);
        */
        $text = ereg_replace("=\r", "\r", $text);
        return $text;
    }

    function make_link_clickable($text){
        $text = eregi_replace("([[:alnum:]]+)://([^[:space:]]*)([[:alnum:]#?/&=])",
            "<a class=\"autolink\" href=\"\\1://\\2\\3\" target=\"_new\">\\1://\\2\\3</a>", $text);
        $text = eregi_replace("([0-9a-z]([-_.]?[0-9a-z])*@[0-9a-z]([-.]?[0-9a-z])*\\.[a-z]{2,3})","<a class=\"autolink\"  href=\"newmsg.php?mailto=\\1&nameto=\\1\">\\1</a>", $text);
        return $text;
    }

    function process_message($header,$body) {
        global $mime_show_html;
        $mail_info = $this->get_mail_info($header);

        $ctype = $mail_info["content-type"];
        $ctenc = $mail_info["content-transfer-encoding"];

        if($ctype == "") $ctype = "text/plain";

        $type = $ctype;

        $ctype = split(";",$ctype);
        $types = split("/",$ctype[0]);

        $maintype = strtolower($types[0]);
        $subtype = strtolower($types[1]);

        switch($maintype) {
        case "text":
            $body = $this->compile_body($body,$ctenc);
            switch($subtype) {
            case "html":
                if(!$mime_show_html)
                    $body = $this->build_text_body(strip_tags($body));
                $msgbody = $body;
                break;
            default:
                $msgbody = $this->build_text_body($body);
                break;
            }
            break;
        case "multipart":
            switch($subtype) {
            case "mixed":
                $boundary = $this->get_boundary($type);
                $part = $this->split_parts($boundary,$body);

                for($i=0;$i<count($part);$i++) {
                    $thispart = trim($part[$i]);

                    if($thispart != "") {
                        $email = $this->fetch_structure($thispart);
    
                        $header = $email["header"];
                        $body = $email["body"];
                        $headers = $this->decode_header($header);
                        $ctype = $headers["content-type"];
    
                        $Actype = split(";",$headers["content-type"]);
                        $types = split("/",$Actype[0]); $rctype = strtolower($Actype[0]);
    
                        if($rctype == "multipart/alternative")
                            $msgbody = $this->build_alternative_body($ctype,$body);
                        elseif($rctype == "text/plain" && strpos($headers["content-disposition"],"name") === false) {
                            $msgbody = $this->build_text_body($this->compile_body($body,$headers["content-transfer-encoding"]));
                        } elseif($rctype == "text/html" && strpos($headers["content-disposition"],"name") === false) {
                            $body = $this->compile_body($body,$headers["content-transfer-encoding"]);
                            if(!$mime_show_html)
                                $body = $this->build_text_body(strip_tags($body));
                            $msgbody = $body;
                        } elseif($rctype == "multipart/related" && strpos($headers["content-disposition"],"name") === false) {
                            $msgbody = $this->build_related_body($ctype,$body);
                        } else {
                            $thisattach = $this->build_attach($header,$body,$boundary,$i);
                        }
                    }
                }
                break;
            case "alternative":
                $msgbody = $this->build_alternative_body($ctype[1],$body);
                break;
            case "related":
                $msgbody = $this->build_related_body($type,$body);
                break;
            default:
                $thisattach = $this->build_attach($header,$body,"",0);
            }
            break;
        default:
            $thisattach = $this->build_attach($header,$body,"",0);
        }
        return $msgbody;
    }

    function build_attach($header,$body,$boundary,$part) {
        global $mail,$temporary_directory,$userfolder;

        $headers = $this->decode_header($header);
        $cdisp = $headers["content-disposition"];
        $ctype = $headers["content-type"]; $ctype2 = explode(";",$ctype); $ctype2 = $ctype2[0];
        
        $Atype = split("/",$ctype);
        $Acdisp = split(";",$cdisp);

        $tenc = $headers["content-transfer-encoding"];

        if($temp) $dir_to_save = $userfolder; //"temporary_files/";

        if($Atype[0] == "message") {
            $divpos = strpos($body,"\n\r");
            $attachheader = substr($body,0,$divpos);
            $attachheaders = $this->decode_header($attachheader);
            $filename = $this->decode_mime_string($attachheaders["subject"]);
            if($filename == "")
                $filename = uniqid("");
            $filename = substr(ereg_replace("[^A-Za-z0-9]","_",$filename),0,20).".eml";
        } else {
            $fname = $Acdisp[1];
            $filename = substr($fname,strpos($fname,"filename=")+9,strlen($fname));
            if($filename == "")
                $filename = substr($ctype,strpos($ctype,"name=")+5,strlen($ctype));
            if(substr($filename,0,1) == "\"" && substr($filename,-1) == "\"")
                $filename = substr($filename,1,strlen($filename)-2);
            $filename = $this->decode_mime_string($filename);
        }


        if($Atype[0] != "message")
            $body = $this->compile_body($body,$tenc);

        $indice = count($this->content["attachments"]);
        $this->content["attachments"][$indice]["name"] = $filename;
        $this->content["attachments"][$indice]["size"] = strlen($body);
        $this->content["attachments"][$indice]["temp"] = $temp;
        $this->content["attachments"][$indice]["content-type"] = $ctype2; //$Atype[0];
        $this->content["attachments"][$indice]["content-disposition"] = $Acdisp[0];
        $this->content["attachments"][$indice]["boundary"] = $boundary;
        $this->content["attachments"][$indice]["part"] = $part;
        return $this->content["attachments"][$indice];
    }

    function compile_body($body,$enctype) {
        $enctype = explode(" ",$enctype); $enctype = $enctype[0];
        if(strtolower($enctype) == "base64")
            $body = base64_decode($body);
        elseif(strtolower($enctype) == "quoted-printable")
            $body = $this->decode_qp($body);
        return $body;

    }

    function download_attach($header,$body,$down=1) {
        $headers = $this->decode_header($header);

        $cdisp = $headers["content-disposition"];
        $ctype = $headers["content-type"];

        $type = split(";",$ctype); $type = $type[0];
        $Atype = split("/",$ctype);
        $Acdisp = split(";",$cdisp);
        $tenc = strtolower($headers["content-transfer-encoding"]);

        if($Atype[0] == "message") {
            $divpos = strpos($body,"\n\r");
            $attachheader = substr($body,0,$divpos);
            $attachheaders = $this->decode_header($attachheader);
            $filename = $this->decode_mime_string($attachheaders["subject"]);
            if($filename == "")
                $filename = uniqid("");
            $filename = substr(ereg_replace("[^A-Za-z0-9]","_",$filename),0,20);
            $filename .= ".eml";
        } else {
            $fname = $Acdisp[1];
            $filename = substr($fname,strpos(strtolower($fname),"filename=")+9,strlen($fname));
            if($filename == "")
                $filename = substr($ctype,strpos(strtolower($ctype),"name=")+5,strlen($ctype));
            if(substr($filename,0,1) == "\"" && substr($filename,-1) == "\"")
                $filename = substr($filename,1,strlen($filename)-2);
            $filename = $this->decode_mime_string($filename);
        }

        if($Atype[0] != "message")
            $body = $this->compile_body($body,$tenc);

        $content_type = ($down)?"application/octet-stream":strtolower($type);
        $filesize = strlen($body);

        header("Content-Type: $content_type; name=\"$filename\"\r\n"
        ."Content-Length: $filesize\r\n");
        $cdisp = ($down)?"attachment":"inline";
        header("Content-Disposition: $cdisp; filename=\"$filename\"\r\n");
        echo($body);
    }

    function get_mail_info($header) {
        $myarray = Array();
        $headers = $this->decode_header($header);

        /*
        echo("<pre>");
        print_r($headers);
        echo("</pre>");
        */

        $message_id = $headers["message-id"];

        if(substr($message_id,0,1) == "<" && substr($message_id,-1) == ">")
            $message_id = substr($message_id,1,strlen($message_id)-2);

        $myarray["content-type"] = $headers["content-type"];
        $myarray["content-transfer-encoding"] = str_replace("GM","-",$headers["content-transfer-encoding"]);
        $myarray["message-id"] = $message_id;

        $received = $headers["received"];

        if($received != "") {
            $received = explode(";",$received);
            $mydate = $received[1];
        } else
            $mydate = $headers["date"];

        $myarray["date"] = $this->build_mime_date($mydate);
        $myarray["subject"] = $this->decode_mime_string($headers["subject"]);
        $myarray["from"] = $this->get_names($headers["from"]);
        $myarray["to"] = $this->get_names($headers["to"]);
        $myarray["clearcase/" target="_blank" >cc"] = $this->get_names($headers["cc"]);
        $myarray["status"] = $headers["status"];
        $myarray["read"] = ($headers["status"] == "N")?0:1;

        return $myarray;

    }

    function build_mime_date($mydate) {

        $mydate = explode(",",$mydate);
        $mydate = trim($mydate[count($mydate)-1]);
        $parts = explode(" ",$mydate);
        if(count($parts) < 4) { return time(); }
        $day = $parts[0];

        switch(strtolower($parts[1])) {
            case "jan": $mon = 1; break;
            case "feb":    $mon = 2; break;
            case "mar":    $mon = 3; break;
            case "apr":    $mon = 4; break;
            case "may":    $mon = 5; break;
            case "jun": $mon = 6; break;
            case "jul": $mon = 7; break;
            case "aug": $mon = 8; break;
            case "sep": $mon = 9; break;
            case "oct": $mon = 10; break;
            case "nov": $mon = 11; break;
            case "dec": $mon = 12; break;
        }
        
        $year = $parts[2];
        $ahours = explode(":",$parts[3]);
        $hour = $ahours[0]; $min = $ahours[1]; $sec = $ahours[2];

        return mktime ($hour, $min, $sec, $mon, $day, $year);

    }

    function initialize($email) {
        $email = $this->fetch_structure($email);
        $body = $email["body"];
        $header = $email["header"];
        $mail_info = $this->get_mail_info($header);

        $this->content["headers"] = $header;
        $this->content["date"] = $mail_info["date"];
        $this->content["subject"] = $mail_info["subject"];
        $this->content["message-id"] = $mail_info["message-id"];
        $this->content["from"] = $mail_info["from"];
        $this->content["to"] = $mail_info["to"];
        $this->content["cc"] = $mail_info["cc"];
        $this->content["body"] = $this->process_message($header,$body);
        $this->content["read"] = $mail_info["read"];
    }

    function split_parts($boundary,$body) {
        $startpos = strpos($body,"$boundary")+strlen("$boundary")+2;
        $lenbody = strpos($body,"\r\n$boundary--") - $startpos;
        $body = substr($body,$startpos,$lenbody);
        return split($boundary."\r\n",$body);
    }

    function get_boundary($ctype){
        $boundary = trim(substr($ctype,strpos(strtolower($ctype),"boundary=")+9,strlen($ctype)));
        $boundary = split(";",$boundary);$boundary = $boundary[0];

        if(substr($boundary,0,1) == "\"" && substr($boundary,-1) == "\"")
            $boundary = substr($boundary,1,strlen($boundary)-2);
        $boundary = "--".$boundary;
        return $boundary;
    }

    function set_as($email,$type=1) {
        $status = ($type)?"Y":"N";
        $tempmail = $this->fetch_structure($email);
        $thisheader = $tempmail["header"];
        $mail_info = $this->get_mail_info($thisheader);
        $decoded_headers = $this->decode_header($thisheader);

        while(list($key,$val) = each($decoded_headers))
            if (eregi("status",$key)) {
                $newmail .= ucfirst($key).": $status\r\n"; $headerok = 1;
            } else $newmail .= ucfirst($key).": ".trim($val)."\r\n";
        if(!$headerok) $newmail .= "Status: $status\r\n";
        $newmail = trim($newmail)."\r\n\r\n".trim($tempmail["body"]);
        return $newmail;
    }

}
?>

原文转自：http://www.ltesting.net