php实现记住密码自动登录

function checklogin(){    if(empty($_SESSION['user_info'])){    //检查一下session是不是为空       if(empty($_COOKIE['username']) || empty($_COOKIE['password'])){  //如果session为空，并且用户没有选择记录登录状           header("location:login.php?req_url=".$_SERVER['REQUEST_URI']);  //转到登录页面，记录请求的url，登录后跳转过去，用户体验好。       }else{   //用户选择了记住登录状态           $user = getUserInfo($_COOKIE['username'],$_COOKIE['password']);   //去取用户的个人资料           if(empty($user)){    //用户名密码不对没到取到信息，转到登录页面              header("location:login.php?req_url=".$_SERVER['REQUEST_URI']);           }else{              $_SESSION['user_info'] = $user;   //用户名和密码对了，把用户的个人资料放到session里面           }       }    }  }

username = trim($_POST['username']);  $password = md5(trim($_POST['password']));  $validatecode = $_POST['validateCode'];  $ref_url = $_GET['req_url'];  $remember = $_POST['remember'];    $err_msg = '';  if($validatecode!=$_SESSION['checksum']){     $err_msg = "验证码不正确";  }elseif($username=='' || $password==''){     $err_msg = "用户名和密码都不能为空";  }else{     $row = getUserInfo($username,$password);     if(empty($row)){        $err_msg = "用户名和密码都不正确";     }else{        $_SESSION['user_info'] = $row;        if(!empty($remember)){     //如果用户选择了，记录登录状态就把用户名和加了密的密码放到cookie里面           setcookie("username", $username, time()+3600*24*365);           setcookie("password", $password, time()+3600*24*365);        }        if(strpos($ref_url,"login.php") === false){            header("location:".$ref_url);        }else{            header("location:main_user.php");        }     }  }

function logout(){     unset($_SESSION['user_info']);     if(!empty($_COOKIE['username']) || !empty($_COOKIE['password'])){        setcookie("username", null, time()-3600*24*365);        setcookie("password", null, time()-3600*24*365);     }  }