How to implement login jump to html page function in php

Implementing login jump to HTML page in PHP requires the use of some basic programming skills. The following are the specific steps to implement the process:

1. Create a login page

First, you need to create a login page to collect the user's login credentials. This page will be used to verify user credentials and refer logged in users to other protected pages.

2. Set login verification logic

In PHP, you can create a verification logic to verify whether the credentials entered by the user are valid. This functionality can be achieved using a MySQL database and a PHP session. The specific steps are as follows:

• Record the user name and password entered by the user.
• Compares username and password to account information stored in the MySQL database.
• If the entered username and password match the database, the user credentials are stored in PHP's session variables and redirected to the protected page.
• If the entered username and password do not match, display an error message to the user.

Here is a code example of validation logic:

<?php
// Start the session
session_start();

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

// Include config file
require_once "config.php";

// 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 = $mysqli->prepare($sql)){
            // Bind variables to the prepared statement as parameters
            $stmt->bind_param("s", $param_username);

            // Set parameters
            $param_username = $username;

            // Attempt to execute the prepared statement
            if($stmt->execute()){
                // Store result
                $stmt->store_result();

                // Check if username exists, if yes then verify password
                if($stmt->num_rows == 1){
                    // Bind result variables
                    $stmt->bind_result($id, $username, $hashed_password);
                    if($stmt->fetch()){
                        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
        $stmt->close();
    }

    // Close connection
    $mysqli->close();
}
?>

3. Creating a protected HTML page

In PHP, you can use sessions Variable to verify whether the user is logged in. If the user is logged in, a protected HTML page can be displayed. Otherwise, a redirect to the login page is required.

4. Add PHP code to the login page

In the login page, you can use PHP code to handle form submission and validation. The specific steps are as follows:

• Create a form to submit user credentials.
• When submitting a form, verify that the credentials entered by the user are valid and redirect to a protected page or display an error message.
• If the user is already logged in, automatically redirect to the protected page instead of showing the login form.

The following is a sample code with a login form and PHP code:

<?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.html");
    exit;
}

// Include config file
require_once "config.php";

// 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 = $mysqli->prepare($sql)){
            // Bind variables to the prepared statement as parameters
            $stmt->bind_param("s", $param_username);

            // Set parameters
            $param_username = $username;

            // Attempt to execute the prepared statement
            if($stmt->execute()){
                // Store result
                $stmt->store_result();

                // Check if username exists, if yes then verify password
                if($stmt->num_rows == 1){
                    // Bind result variables
                    $stmt->bind_result($id, $username, $hashed_password);
                    if($stmt->fetch()){
                        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.html");
                        } 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
        $stmt->close();
    }

    // Close connection
    $mysqli->close();
}
?>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Login</title>
    <style>
        body{ font: 14px sans-serif; }
        .wrapper{ width: 350px; padding: 20px; }
    </style>
</head>
<body>
    <div class="wrapper">
        <h2>Login</h2>
        <p>Please fill in your credentials to login.</p>
        <form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="post">
            <div <?php echo (!empty($username_err)) ? &#39;has-error&#39; : &#39;&#39;; ?>">
                <label>Username</label>
                <input type="text" name="username" class="form-control" value="<?php echo $username; ?>">
                <span <?php echo (!empty($username_err)) ? &#39;help-block&#39; : &#39;&#39;; ?>"><?php echo $username_err; ?></span>
            </div>
            <div <?php echo (!empty($password_err)) ? &#39;has-error&#39; : &#39;&#39;; ?>">
                <label>Password</label>
                <input type="password" name="password" class="form-control">
                <span <?php echo (!empty($password_err)) ? &#39;help-block&#39; : &#39;&#39;; ?>"><?php echo $password_err; ?></span>
            </div>
            <div class="form-group">
                <input type="submit" class="btn btn-primary" value="Login">
            </div>
            <p>Don't have an account? <a href="register.html">Sign up now</a>.</p>
        </form>
    </div>
</body>
</html>

The above are the basic steps and code examples for user login to jump to the HTML page through PHP.

The above is the detailed content of How to implement login jump to html page function in php. For more information, please follow other related articles on the PHP Chinese website!