php使用cookie实现记住登录状态

//检查用户是否登录
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"); 
} 
} 
}

//退出登录
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); 
} 
}

<?
//读取COOKIE的用户名和密码的值即可
if($_COOKIE['uname']!=''){$CKUNAME =  $_COOKIE['uname'];}
if($_COOKIE['pwd']!=''){$CKPWD =  $_COOKIE['pwd'];}
echo $CKUNAME;
echo '<br>';
echo $CKPWD;
?>
<form id="form1" name="form1" method="post" action="">
    <input type="text" name="uname" id="uname" value="<?=$CKUNAME;?>" /> <input
       type="password" name="pwd" id="pwd" value="<?=$CKPWD;?>" /> <input
       name="remember" type="checkbox" value="1" <? if($CKUNAME!=''){?>
       checked="checked" <? } ?> /> 记住我! <input type="submit" name="button"
       id="button" value="登录" />
</form>
<?
//登录，将用户名和密码存入到COOKIE
if($_POST['button']!=''){
    $uname = $_POST['uname'];
    $pwd = $_POST['pwd'];
    //如果输入的加密密码和COOKIE中不一样，那么就加密
    if($pwd!=$CKPWD){$pwd = md5($pwd);}
    $remember = $_POST['remember'];
    if($remember==1){
       setcookie("uname", $uname, time()+3600*24*30);
       setcookie("pwd", $pwd, time()+3600*24*30);
    }
}
?>