php get post传递数据 安全问题

/**
* @name date safe class 0.1
* @author kevin xu
* @copyright kenvin E-mail:gincn@cn.cashboxparty.com MSN:gincn@live.cn
*/
interface dateSafe{
 function gincn();
}
class safe extends doSafe implements dateSafe
{
 public $safe;
 function __construct($safe)
 {
  parent::__construct($safe);       //调用父类构造函数,网友javachen找出来的错误
  $this->safe = $safe;
 }
 function gincn()
 {
  $this->safe = parent::xss($this->safe);
  $this->safe = parent::sql($this->safe);
  return $this->safe;
 }
}
class doSafe
{
 protected  $str;
 function __construct($str)
 {
  $this->str = $str;
 }
 function xss()
 {
  $this->str = trim($this->str);         //清理空格字符
  $this->str = nl2br($this->str);         //将换行符转化为

  $this->str = strip_tags($this->str);      //过滤文本中的HTML标签
  $this->str = htmlspecialchars($this->str);    //将文本中的内容转换为HTML实体
  $this->str = addslashes($this->str);      //加入字符转义
  return $this->str;
 }
 function sql()
 {
  $this->str = mysql_escape_string($this->str);
  return $this->str;
 }
}

?>