如何在未登录php时重定向

Question

我已经在我的登录表单中构建了一个PHP登录网络，人们可以登录，如果信息是正确的，那么他们将被重定向到welcome.php。现在，任何人都可以直接访问这个页面-这是我的登录代码

<?php
require_once "config.php";
// Initialize the session
session_start();

// Check if the user is already logged in, if yes then redirect him to welcome page
if(isset($_SESSION["loggedin"]) && $_SESSION["loggedin"] === true){
  header("location: welcome.php");
  exit;
}

// Include config file


// Define variables and initialize with empty values
$username = $password = "";
$username_err = $password_err = "";

// Processing form data when form is submitted
if($_SERVER["REQUEST_METHOD"] == "POST"){

    // Check if username is empty
    if(empty(trim($_POST["username"]))){
        $username_err = "Please enter username.";
    } else{
        $username = trim($_POST["username"]);
    }

    // Check if password is empty
    if(empty(trim($_POST["password"]))){
        $password_err = "Please enter your password.";
    } else{
        $password = trim($_POST["password"]);
    }

    // Validate credentials
    if(empty($username_err) && empty($password_err)){
        // Prepare a select statement
        $sql = "SELECT id, username, password FROM users WHERE username = ?";

        if($stmt = mysqli_prepare($con, $sql)){
            // Bind variables to the prepared statement as parameters
            mysqli_stmt_bind_param($stmt, "s", $param_username);

            // Set parameters
            $param_username = $username;

            // Attempt to execute the prepared statement
            if(mysqli_stmt_execute($stmt)){
                // Store result
                mysqli_stmt_store_result($stmt);

                // Check if username exists, if yes then verify password
                if(mysqli_stmt_num_rows($stmt) == 1){                    
                    // Bind result variables
                    mysqli_stmt_bind_result($stmt, $id, $username, $hashed_password);
                    if(mysqli_stmt_fetch($stmt)){
                        if(password_verify($password, $hashed_password)){
                            // Password is correct, so start a new session
                            session_start();

                            // Store data in session variables
                            $_SESSION["loggedin"] = true;
                            $_SESSION["id"] = $id;
                            $_SESSION["username"] = $username;                            

                            // Redirect user to welcome page
                            header("location: welcome.php");
                        } else{
                            // Display an error message if password is not valid
                            $password_err = "The password you entered was not valid.";
                        }
                    }
                } else{
                    // Display an error message if username doesn't exist
                    $username_err = "No account found with that username.";
                }
            } else{
                echo "Oops! Something went wrong. Please try again later.";
            }
        }

        // Close statement
        mysqli_stmt_close($stmt);
    }

    // Close connection
    mysqli_close($con);
}
?>

我在welcome.php上试过这个，但不起作用

<?php
session_start(); 
include 'config.php';

if (empty($_SESSION['user'])) {
    header('Location: index.php');
    exit;
}

?>

Answer 1

因为您在登录期间为用户名设置了会话。

假设您希望保护页面welcome.php，以确保只有登录用户才能访问它。

复制下面的代码并将其粘贴到( welcome.php页面的最顶端)。您可以对您想要保护的任何其他页面执行同样的操作，它将工作。

代码应该首先放在页面的顶部-- eg.welcome.php、dashboard.php等。

<?php

session_start();
if(!isset($_SESSION['username']) || (trim($_SESSION['username']) == '')) {
        header("location: login.php");
        exit();
    }

?>

Answer 2

在welcome.php中，您应该更好地检查用户当前状态。

和登录页面一样，您应该检查用户cookie，它是在代码中按名称$_SESSION‘’loggedin设置的。

若要检查用户是否有此cookie，并将cookie设置为true，请使用以下代码

if(isset($_SESSION["loggedin"]) && $_SESSION["loggedin"] === true){
  header("location: login.php");
}