dsmvqp3124 2014-03-25 04:14
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PHP表单需要提交两次以设置会话

So I am trying to implement a login on my website but for some reason the form needs to have submit pressed twice to effectively login. I am at a complete loss as to why 

<?php
    session_start();
if(isset($_SESSION["username"])){
        print('<p>'.$_SESSION["username"]." is currently logged in");
        print('<form action="logout.php"><input type="submit" value="Log out"></form>');
    }
else{
print('<form action="index.php" method="post">
        Username: <input type="text" name="username"/><br/>
        Password: <input type="password" name="password"/><br/>
        <input type="submit" value="Log In" name="submit"/>
    </form>');
include('config.php');

if(isset($_POST['submit'])) {
    $username = mysql_real_escape_string(htmlentities($_POST['username']));
    $password = hash('sha256', mysql_real_escape_string(htmlentities($_POST['password'])));
    $mysqli = new mysqli( DB_HOST, DB_USER, DB_PASSWORD, DB_NAME );
    $qstring = 'SELECT * FROM login WHERE username = "'.$username.'" AND password = "'.$password.'"';
    $result = $mysqli->query($qstring);
    if($result->num_rows ==1)
    {

        $_SESSION['username']=$username;
        $_SESSION['password']=$password;       
    }
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  • dounieliang4712 2014-03-25 04:33
    关注

    Since you have all your code for login, processing and showing the user is logged in at the same page with no redirect after the user is successful logged in, it takes you 2 submits to see the logged in page.

    I would suggest you splitting your login page from what you currently have into a login.php and a home.php.

    Also you should avoid querying for username and password, you should only need to retrieve the username and compare the password instead and also avoid saving the password on the session its extremely unneeded.

    login.php would have:

    <?php
session_start();
// Your database info
$db_host = '';
$db_user = '';
$db_pass = '';
$db_name = '';

if (isset($_SESSION['username']))
{
    // If the user is already logged in send to home
    header("Location: home.php");
}
else
{
    // if the user is not logged in but have submitted the login page, 
    // check its credentials and redirect to home page
    if (isset($_POST['submit']))
    {
        if (isset($_POST['username']) && isset($_POST['password']))
        {
            $con = mysqli_connect($db_host, $db_user, $db_pass, $db_name);
            if ($con->connect_error)
            {
                die('Connect Error (' . mysqli_connect_errno() . ') '. mysqli_connect_error());
            }

            $sql = "SELECT username, password FROM login WHERE username = ?";
            if (!$result = $con->prepare($sql))
            {
                die('Query failed: (' . $con->errno . ') ' . $con->error);
            }

            if (!$result->bind_param('s', $_POST['username']))
            {
                die('Binding parameters failed: (' . $result->errno . ') ' . $result->error);
            }

            if (!$result->execute())
            {
                die('Execute failed: (' . $result->errno . ') ' . $result->error);
            }

            $result->store_result();
            if ($result->num_rows == 0)
            {
                die('No username found...');
            }

            $password = hash('sha256', $_POST['password']);
            $result->bind_result($db_username, $db_password);
            $result->fetch();

            if ($password == $db_password)
            {
                $_SESSION['username'] = $db_username;
                header("Location: home.php");
                exit;
            }
            else
            {
                $error = "Username or password does not match...";
            }
        }
        else
        {
            $error = "Fill the username and password to login...";
        }
    }
}
// Show the form and/or possible error messages to user if applicable
?>
<html>
<head>
<title>Login Page</title>
</head>
<body>
<?php if (isset($error)) echo $error, '<br>'; ?>
<form method="POST" action="index.php">
<label>Username</label><br /><input type="text" name="username" value=""><br />
<label>Password</label><br /><input type="password" name="password" value=""><br />
<input type="submit" name="submit" value="Login">
</form>
</body>
</html>

    And at home.php:

    <?php
session_start();
if (!isset($_SESSION['username']))
{
    // send user back to login page if he is not logged in
    header("Location: login.php");
    exit;
}
// show the home page
?>
<p><? echo $_SESSION["username"]; ?> is currently logged in.
<form action="logout.php">
<input type="submit" value="Log out">
</form>
    本回答被题主选为最佳回答 , 对您是否有帮助呢?
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