很久没来这里了，各位可好？！

//ubbcode类
class ubbcode{
var $call_time=0;
//可处理标签及处理函数对应表
var $tags = array( //小写的标签 => 对应的处理函数
'url' => '$this->url',
'email' => '$this->email',
'img' => '$this->img',
'flash' => '$this->flash',
'sound' => '$this->sound',

'black' => '$this->font_color',
'white' => '$this->font_color',
'red' => '$this->font_color',
'pink' => '$this->font_color',
'blue' => '$this->font_color',
'green' => '$this->font_color',
'olive' => '$this->font_color',
'navy' => '$this->font_color',
'gray'=> '$this->font_color',
'fuchsia' => '$this->font_color',
'yellow' => '$this->font_color',
'silver' => '$this->font_color',
'purple' => '$this->font_color',

'marquee' => '$this->simple',
'b' => '$this->simple',
'i' => '$this->simple',
'u' => '$this->simple',
'tt' => '$this->simple',
's' => '$this->simple',
'strike' => '$this->simple',
'h1' => '$this->simple',
'h2' => '$this->simple',
'h3' => '$this->simple',
'h4' => '$this->simple',
'h5' => '$this->simple',
'h6' => '$this->simple',
'sup' => '$this->simple',
'sub' => '$this->simple',
'em' => '$this->simple',
'strong' => '$this->simple',
'code' => '$this->simple',
'samp' => '$this->simple',
'kbd' => '$this->simple',
'var' => '$this->simple',
'dfn' => '$this->simple',
'cite' => '$this->simple',
'small' => '$this->simple',
'big' => '$this->simple',
'blink' => '$this->simple'
);
//url裢接属性
var $attr_url;
//url合法性检查对象
var $urlcheck;

function ubbcode($attr_url){
$this->attr_url = ''.$attr_url;
$this->urlcheck = new urlcheck();
}

//对$str进行UBB编码解析
function parse($str){
$this->call_time++;
$parse = ''.htmlencode($str);

$ret = '';
while(true){
$eregi_ret=eregi("\[[#]{0,1}[[:alnum:]]{1,7}\]",$parse,$eregi_arr); //查找[xx]
if(!$eregi_ret){
$ret .= $parse;
break; //如果没有，返回
}
$pos = @strpos($parse,$eregi_arr[0]);
$tag_len=strlen($eregi_arr[0])-2;//标记长度
$tag_start=substr($eregi_arr[0],1,$tag_len);
$tag=strtolower($tag_start);

if((($tag=="url") or ($tag=="email") or ($tag=="img") or ($tag=="flash")) and ($this->call_time>1)){
echo $this->call_time."
";
return $parse;//如果不能是不能嵌套的标记，直接返回
}

$parse2 = substr($parse,0,$pos);//标记之前
$parse = substr($parse,$pos+$tag_len+2);//标记之后
if(!isset($this->tags[$tag])){
echo "$tag_start
";
$ret .= $parse2.'['.$tag_start.']';
continue;//如果是不支持的标记
}

//查找对对应的结束标记
$eregi_ret=eregi("\[\/".$tag."\]",$parse,$eregi_arr);
if(!$eregi_ret){
$ret .= $parse2.'['.$tag_start.']';
continue;//如果没有对应该的结束标记
}
$pos=strpos($parse,$eregi_arr[0]);
$value=substr($parse,0,$pos);//这是起止标记之间的内容
$tag_end=substr($parse,$pos+2,$tag_len);
$parse=substr($parse,$pos+$tag_len+3);//结束标记之后的内容

if(($tag!="url") and ($tag!="email") and ($tag!="img")and ($tag!="flash")){
$value=$this->parse($value);
}

$ret .= $parse2;
eval('$ret .= '.$this->tags[$tag].'("'.$tag_start.'","'.$tag_end.'","'.$value.'");');
}
$this->call_time--;
return $ret;
}

function simple($start,$end,$value){
return ''.$value.''.$end.'>';
}

function url($start,$end,$value){
$trim_value=trim($value);
if (strtolower(substr($trim_value,0,7))!="http://")
$trim_value="http://".$trim_value;
if($this->urlcheck->check($trim_value)) return 'attr_url.'>'.$value.'';
else return '['.$start.']'.$value.'[/'.$end.']';
}

function email($start,$end,$value){
if(emailcheck($value)) return ''.$value.'';
else return '['.$start.']'.$value.'[/'.$end.']';
}

function img($start,$end,$value){
$trim_value=trim($value);
if ((strtolower(substr($trim_value,0,7))!="http://") or ($this->urlcheck->check($trim_value)))
return '';
else return '['.$start.']'.$value.'[/'.$end.']';
}

function flash($start,$end,$value){
$trim_value=trim($value);
if ((strtolower(substr($trim_value,0,7))!="http://") or ($this->urlcheck->check($trim_value)))

return '';

else return '['.$start.']'.$value.'[/'.$end.']';
}

function sound($start,$end,$value){
$trim_value=trim($value);
if ((strtolower(substr($trim_value,0,7))!="http://") or ($this->urlcheck->check($trim_value)))

return "";

else return '['.$start.']'.$value.'[/'.$end.']';
}

function font_color($start,$end,$value){
if(strstr("black|white|red|pink|blue|green|olive|navy|gray|fuchsia|yellow|silver|purple",$start))
return "".$value."";
else return '['.$start.']'.$value.'[/'.$end.']';
}
}

//urlcheck.php
class urlcheck{
var $regex = array(//协议名(注意在这里必须写成小写) => 对应的正则表达式
'ftp' => '$this->ftpurl',
'file' => '$this->fileurl',
'http' => '$this->httpurl',
'https' => '$this->httpurl',
'gopher' => '$this->gopherurl',
'news' => '$this->newsurl',
'nntp' => '$this->nntpurl',
'telnet' => '$this->telneturl',
'wais' => '$this->waisurl'
);

var $lowalpha;
var $hialpha;
var $alpha;
var $digit;
var $safe;
var $extra;
var $national;
var $punctuation;
var $reserved;
var $hex;
var $escape;
var $unreserved;
var $uchar;
var $xchar;
var $digits;

var $urlpath;
var $password;
var $user;
var $port;
var $hostnumber;
var $alphadigit;
var $toplabel;
var $domainlabel;
var $hostname;
var $host;
var $hostport;
var $login;

//ftp
var $ftptype;
var $fsegment;
var $fpath;
var $ftpurl;

//file
var $fileurl;

//http,https
var $search;
var $hsegment;
var $hpath;
var $httpurl;

//gopher
var $gopher_string;
var $selector;
var $gtype;
var $gopherurl;

//news
var $article;
var $group;
var $grouppart;
var $newsurl;

//nntp
var $nntpurl;

//telnet
var $telneturl;

//wais
var $wpath;
var $wtype;
var $database;
var $waisdoc;
var $waisindex;
var $waisdatabase;
var $waisurl;

function check($url){
$pos = @strpos($url,':',1);
if($pos $prot = substr($url,0,$pos);
if(!isset($this->regex[$prot])) return false;
eval('$regex = '.$this->regex[$prot].';');
return ereg('^'.$regex.'$',$url);
}

function urlcheck(){
$this->lowalpha = '[a-z]';
$this->hialpha = '[A-Z]';
$this->alpha = '('.$this->lowalpha.'|'.$this->hialpha.')';
$this->digit = '[0-9]';
$this->safe = '[$.+_-]';
$this->extra = '[*()\'!,]';
$this->national = '([{}|\^~`]|\\[|\\])';
$this->punctuation = '[#%"]';
$this->reserved = '[?;/:@&=]';
$this->hex = '('.$this->digit.'|[a-fA-F])';
$this->escape = '(%'.$this->hex.'{2})';
$this->unreserved = '('.$this->alpha.'|'.$this->digit.'|'.$this->safe.'|'.$this->extra.')';
$this->uchar = '('.$this->unreserved.'|'.$this->escape.')';
$this->xchar = '('.$this->unreserved.'|'.$this->reserved.'|'.$this->escape.')';
$this->digits = '('.$this->digit.'+)';

$this->urlpath = '('.$this->xchar.'*)';
$this->password = '(('.$this->uchar.'|[?;&=]'.')*)';
$this->user = '(('.$this->uchar.'|[?;&=]'.')*)';
$this->port = $this->digits;
$this->hostnumber = '('.$this->digits.'.'.$this->digits.'.'.$this->digits.'.'.$this->digits.')';
$this->alphadigit = '('.$this->alpha.'|'.$this->digit.')';
$this->toplabel = '('.$this->alpha.'|('.$this->alpha.'('.$this->alphadigit.'|-)*'.$this->alphadigit.'))';
$this->domainlabel = '('.$this->alphadigit.'|('.$this->alphadigit.'('.$this->alphadigit.'|-)*'.$this->alphadigit.'))';
$this->hostname = '(('.$this->domainlabel.'\\.)*'.$this->toplabel.')';
$this->host = '('.$this->hostname.'|'.$this->hostnumber.')';
$this->hostport = '('.$this->host.'(:'.$this->port.')?)';
$this->login = '(('.$this->user.'(:'.$this->password.')?@)?'.$this->hostport.')';

$this->ftptype = '[aidAID]';
$this->fsegment = '(('.$this->uchar.'|[?:@&=])*)';
$this->fpath = '('.$this->fsegment.'(/'.$this->fsegment.')*)';
$this->ftpurl = '([fF][tT][pP]://'.$this->login.'(/'.$this->fpath.'(;[tT][yY][pP][eE]='.$this->ftptype.')?)?)';

$this->fileurl = '([fF][iI][lL][eE]://('.$this->host.'|[lL][oO][cC][aA][lL][hH][oO][sS][tT])?/'.$this->fpath.')';

$this->search = '(('.$this->uchar.'|[;:@&=])*)';
$this->hsegment = '(('.$this->uchar.'|[;:@&=])*)';
$this->hpath = '('.$this->hsegment.'(/'.$this->hsegment.')*)';
$this->httpurl = '([hH][tT][tT][pP][sS]?://'.$this->hostport.'(/'.$this->hpath.'([?]'.$this->search.')?)?)';

$this->gopher_string = '('.$this->xchar.'*)';
$this->selector = '('.$this->xchar.'*)';
$this->gtype = $this->xchar;
$this->gopherurl = '([gG][oO][pP][hH][eE][rR]://'.$this->hostport.'(/('.$this->gtype.'('.$this->selector.'(%09'.$this->search.'(%09'.$this->gopher_string.')?)?)?)?)?)';

$this->article = '(('.$this->uchar.'|[;/?:&=])+@'.$this->host.')';
$this->group = '('.$this->alpha.'('.$this->alpha.'|'.$this->digit.'|[-.+_])*)';
$this->grouppart = '([*]|'.$this->group.'|'.$this->article.')';
$this->newsurl = '([nN][eE][wW][sS]:'.$this->grouppart.')';

$this->nntpurl = '([nN][nN][tT][pP]://'.$this->hostport.'/'.$this->group.'(/'.$this->digits.')?)';

$this->telneturl = '([tT][eE][lL][nN][eE][tT]://'.$this->login.'/?)';

$this->wpath = '('.$this->uchar.'*)';
$this->wtype = '('.$this->uchar.'*)';
$this->database = '('.$this->uchar.'*)';
$this->waisdoc = '([wW][aA][iI][sS]://'.$this->hostport.'/'.$this->database.'/'.$this->wtype.'/'.$this->wpath.')';
$this->waisindex = '([wW][aA][iI][sS]://'.$this->hostport.'/'.$this->database.'[?]'.$this->search.')';
$this->waisdatabase = '([wW][aA][iI][sS]://'.$this->hostport.'/'.$this->database.')';
$this->waisurl = '('.$this->waisdatabase.'|'.$this->waisindex.'|'.$this->waisdoc.')';
}
}


function htmlencode($str){
$str = (string)$str;

$ret = '';
$len = strlen($str);
$nl = false;
for($i=0;$i $chr = $str[$i];
switch($chr){
case ' $ret .= ' $nl = false;
break;
case '>':
$ret .= '>';
$nl = false;
break;
case '"':
$ret .= '"';
$nl = false;
break;
case '&':
$ret .= '&';
$nl = false;
break;
/*
case ' ':
$ret .= ' ';
$nl = false;
break;
*/
case chr(9):
$ret .= ' ';
$nl = false;
break;
/*
case chr(10):
if($nl) $nl = false;
else{
$ret .= '
';
$nl = true;
}
break;

case chr(13):
if($nl) $nl = false;
else{
$ret .= '
';
$nl = true;
}
break;
*/
default:
$ret .= $chr;
$nl = false;
break;
}
}

return $ret;
}


function htmlencode4textarea($str){
$str = (string)$str;

$ret = '';
$len = strlen($str);
for($i=0;$i $chr = $str[$i];
switch($chr){
case ' $ret .= ' break;
case '>':
$ret .= '>';
break;
case '"':
$ret .= '"';
break;
case '&':
$ret .= '&';
break;
case ' ':
$ret .= ' ';
break;
case chr(9):
$ret .= ' ';
break;
default:
$ret .= $chr;
break;
}
}

return $ret;
}

function emailcheck($email){
$ret=false;
if(strstr($email, '@') && strstr($email, '.')){
if(eregi("^([_a-z0-9]+([\\._a-z0-9-]+)*)@([a-z0-9]{2,}(\\.[a-z0-9-]{2,})*\\.[a-z]{2,3})$", $email)){
$ret=true;
}
}
return $ret;
}

function str2url($path){
return eregi_replace("%2f","/",urlencode($path));
}

?>
--------------------------

说明：在网上找了半天发现全是何志强的那段代码，我也就拿来改了一下用上了。其中加入了一部分自己的内容，只是还不太清楚如何规定图片等元素的大小。我曾经把 function img($start,$end,$value){
$trim_value=trim($value);
if ((strtolower(substr($trim_value,0,7))!="http://") or ($this->urlcheck->check($trim_value)))
return '';
else return '['.$start.']'.$value.'[/'.$end.']';
}
改为：
function img($start,$end,$value){
$trim_value=trim($value);
if ((strtolower(substr($trim_value,0,7))!="http://") or ($this->urlcheck->check($trim_value)))
{
$pisces=explode(" ",$start);
if(!is_int($pisces[1]) || !!is_int($pisces[2]))
return '';
else
return '';
}

else return '['.$start.']'.$value.'[/'.$end.']';
}

但由于对前面的正则表达式不熟悉没成功。