function _goBack($msg=null,$get=array()) {
$url = $_SESSION['BACKURL'];
if($get!=array())
foreach ($get as $k=>$g){
$url.=''.$k.'='.$g;//先追加所有要追加的參數(shù)，不管是否重復(fù)
if(count(explode("{$k}=",$url))>2){//假如以"a="這種格式分割目前url字符串發(fā)現(xiàn)有超過兩個的分割數(shù)組，即表明該字符串有重復(fù)參數(shù)
$url=preg_replace("/{$k}=[a-zA-Z0-9]*/",'',$url);//正則替換所有"a=x"為空
}
}
unset($_SESSION['BACKURL']);
$this->alert($msg,$url);
}