我无法连接到mysql？ [关闭]

here is my code please help me to solve this prob.i think error is inside the function. compiler show error on line 9. thanks in advance

<?php

class db_connector{
var $db_dsn="mysql:host=localhost;dbname=erp5_temp2";
var $db_username = "root";
var $db_password = "";
var $dbh ="";

    public db_connector(){  
        $dbh = new PDO($this->$db_dsn,$this->$db_username,$this->$db_password);
        $dbh->setAttribute(PDO::ATTR_EMULATE_PREPARES,TRUE);
    }
    public get_db_handler(){
        return $dbh;
    }
}

?>

You forgot function keyword:

class ClassName
{
    public function methodName()
    {
        // ...
    }
}

You need to function statement:

<?php

class db_connector{
    var $db_dsn="mysql:host=localhost;dbname=erp5_temp2";
    var $db_username = "root";
    var $db_password = "";
    var $dbh ="";

    public function db_connector(){  
        $dbh = new PDO($this->$db_dsn,$this->$db_username,$this->$db_password);
        $dbh->setAttribute(PDO::ATTR_EMULATE_PREPARES,TRUE);
    }
    public function get_db_handler(){
        return $dbh;
    }
}

?>