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第 17 章：常用功能开发 ​

17.1 发送邮件 ​

使用 PHP 内置 mail() 函数 ​

php
<?php
$to = "recipient@example.com";
$subject = "测试邮件";
$message = "这是一封测试邮件";
$headers = "From: sender@example.com\r\n";
$headers .= "Reply-To: sender@example.com\r\n";
$headers .= "Content-Type: text/html; charset=UTF-8\r\n";

if (mail($to, $subject, $message, $headers)) {
    echo "邮件发送成功";
} else {
    echo "邮件发送失败";
}
?>

使用 PHPMailer（推荐） ​

php
<?php
use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\SMTP;

require 'vendor/autoload.php';

$mail = new PHPMailer(true);

try {
    // 服务器配置
    $mail->SMTPDebug = SMTP::DEBUG_SERVER;
    $mail->isSMTP();
    $mail->Host = 'smtp.example.com';
    $mail->SMTPAuth = true;
    $mail->Username = 'user@example.com';
    $mail->Password = 'password';
    $mail->SMTPSecure = PHPMailer::ENCRYPTION_STARTTLS;
    $mail->Port = 587;

    // 收发件人
    $mail->setFrom('from@example.com', '发件人名称');
    $mail->addAddress('to@example.com', '收件人名称');

    // 内容
    $mail->isHTML(true);
    $mail->Subject = '测试邮件';
    $mail->Body = '<h1>这是一封测试邮件</h1><p>邮件内容</p>';
    $mail->AltBody = '这是纯文本内容';

    $mail->send();
    echo '邮件发送成功';
} catch (Exception $e) {
    echo "邮件发送失败: {$mail->ErrorInfo}";
}
?>

17.2 验证码 ​

生成验证码图片 ​

php
<?php
session_start();

// 生成验证码
$code = '';
$chars = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
for ($i = 0; $i < 4; $i++) {
    $code .= $chars[rand(0, strlen($chars) - 1)];
}

// 存储到 session
$_SESSION['captcha'] = $code;

// 创建图片
$width = 100;
$height = 30;
$image = imagecreatetruecolor($width, $height);

// 设置颜色
$bg_color = imagecolorallocate($image, 255, 255, 255);
$text_color = imagecolorallocate($image, 0, 0, 0);

// 填充背景
imagefill($image, 0, 0, $bg_color);

// 添加干扰线
for ($i = 0; $i < 5; $i++) {
    $line_color = imagecolorallocate($image, rand(0, 255), rand(0, 255), rand(0, 255));
    imageline($image, rand(0, $width), rand(0, $height), rand(0, $width), rand(0, $height), $line_color);
}

// 添加文字
imagestring($image, 5, 20, 7, $code, $text_color);

// 输出图片
header('Content-Type: image/png');
imagepng($image);
imagedestroy($image);
?>

验证验证码 ​

php
<?php
session_start();

if (isset($_POST['captcha'])) {
    if (strtolower($_POST['captcha']) === strtolower($_SESSION['captcha'])) {
        echo "验证码正确";
    } else {
        echo "验证码错误";
    }
}
?>

<!-- HTML 表单 -->
<form method="post">
    <img src="captcha.php" alt="验证码"><br>
    <input type="text" name="captcha" placeholder="请输入验证码"><br>
    <button type="submit">提交</button>
</form>

17.3 分页功能 ​

分页实现 ​

php
<?php
// 连接数据库
$conn = mysqli_connect("localhost", "root", "", "myDB");

// 每页显示数量
$per_page = 10;

// 当前页码
$page = isset($_GET['page']) ? (int)$_GET['page'] : 1;
if ($page < 1) $page = 1;

// 计算偏移量
$offset = ($page - 1) * $per_page;

// 查询总记录数
$sql = "SELECT COUNT(*) as total FROM articles";
$result = mysqli_query($conn, $sql);
$row = mysqli_fetch_assoc($result);
$total = $row['total'];

// 计算总页数
$total_pages = ceil($total / $per_page);

// 查询当前页数据
$sql = "SELECT * FROM articles LIMIT $offset, $per_page";
$result = mysqli_query($conn, $sql);

// 显示数据
while ($row = mysqli_fetch_assoc($result)) {
    echo $row['title'] . '<br>';
}

// 显示分页链接
echo '<div class="pagination">';
if ($page > 1) {
    echo '<a href="?page=' . ($page - 1) . '">上一页</a>';
}

for ($i = 1; $i <= $total_pages; $i++) {
    if ($i == $page) {
        echo '<span>' . $i . '</span>';
    } else {
        echo '<a href="?page=' . $i . '">' . $i . '</a>';
    }
}

if ($page < $total_pages) {
    echo '<a href="?page=' . ($page + 1) . '">下一页</a>';
}
echo '</div>';

mysqli_close($conn);
?>

分页函数封装 ​

php
<?php
function paginate($total, $per_page, $current_page, $url) {
    $total_pages = ceil($total / $per_page);
    
    $html = '<div class="pagination">';
    
    // 上一页
    if ($current_page > 1) {
        $html .= '<a href="' . $url . '?page=' . ($current_page - 1) . '">上一页</a>';
    }
    
    // 页码
    $start = max(1, $current_page - 2);
    $end = min($total_pages, $current_page + 2);
    
    if ($start > 1) {
        $html .= '<a href="' . $url . '?page=1">1</a>';
        if ($start > 2) {
            $html .= '<span>...</span>';
        }
    }
    
    for ($i = $start; $i <= $end; $i++) {
        if ($i == $current_page) {
            $html .= '<span class="current">' . $i . '</span>';
        } else {
            $html .= '<a href="' . $url . '?page=' . $i . '">' . $i . '</a>';
        }
    }
    
    if ($end < $total_pages) {
        if ($end < $total_pages - 1) {
            $html .= '<span>...</span>';
        }
        $html .= '<a href="' . $url . '?page=' . $total_pages . '">' . $total_pages . '</a>';
    }
    
    // 下一页
    if ($current_page < $total_pages) {
        $html .= '<a href="' . $url . '?page=' . ($current_page + 1) . '">下一页</a>';
    }
    
    $html .= '</div>';
    
    return $html;
}

// 使用
echo paginate(100, 10, 5, 'articles.php');
?>

17.4 接口开发（返回 JSON） ​

创建 API 接口 ​

php
<?php
header('Content-Type: application/json; charset=utf-8');

// 连接数据库
$conn = mysqli_connect("localhost", "root", "", "myDB");

// 获取请求方法
$method = $_SERVER['REQUEST_METHOD'];

// 获取请求数据
$input = json_decode(file_get_contents('php://input'), true);

switch ($method) {
    case 'GET':
        // 查询数据
        $sql = "SELECT * FROM articles";
        $result = mysqli_query($conn, $sql);
        $data = [];
        while ($row = mysqli_fetch_assoc($result)) {
            $data[] = $row;
        }
        echo json_encode([
            'code' => 200,
            'message' => 'success',
            'data' => $data
        ]);
        break;
        
    case 'POST':
        // 添加数据
        $title = mysqli_real_escape_string($conn, $input['title']);
        $content = mysqli_real_escape_string($conn, $input['content']);
        
        $sql = "INSERT INTO articles (title, content) VALUES ('$title', '$content')";
        if (mysqli_query($conn, $sql)) {
            echo json_encode([
                'code' => 200,
                'message' => '添加成功',
                'data' => ['id' => mysqli_insert_id($conn)]
            ]);
        } else {
            echo json_encode([
                'code' => 500,
                'message' => '添加失败'
            ]);
        }
        break;
        
    case 'PUT':
        // 更新数据
        $id = (int)$input['id'];
        $title = mysqli_real_escape_string($conn, $input['title']);
        $content = mysqli_real_escape_string($conn, $input['content']);
        
        $sql = "UPDATE articles SET title = '$title', content = '$content' WHERE id = $id";
        if (mysqli_query($conn, $sql)) {
            echo json_encode([
                'code' => 200,
                'message' => '更新成功'
            ]);
        } else {
            echo json_encode([
                'code' => 500,
                'message' => '更新失败'
            ]);
        }
        break;
        
    case 'DELETE':
        // 删除数据
        $id = (int)$_GET['id'];
        
        $sql = "DELETE FROM articles WHERE id = $id";
        if (mysqli_query($conn, $sql)) {
            echo json_encode([
                'code' => 200,
                'message' => '删除成功'
            ]);
        } else {
            echo json_encode([
                'code' => 500,
                'message' => '删除失败'
            ]);
        }
        break;
        
    default:
        echo json_encode([
            'code' => 405,
            'message' => '不支持的请求方法'
        ]);
}

mysqli_close($conn);
?>

17.5 AJAX 交互（无刷新） ​

前端 AJAX 请求 ​

html
<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>AJAX 示例</title>
    <script>
        // 原生 JavaScript AJAX
        function loadData() {
            var xhr = new XMLHttpRequest();
            xhr.open('GET', 'api.php', true);
            xhr.onload = function() {
                if (this.status === 200) {
                    var data = JSON.parse(this.responseText);
                    console.log(data);
                    // 更新页面
                    var html = '';
                    data.data.forEach(function(item) {
                        html += '<div>' + item.title + '</div>';
                    });
                    document.getElementById('result').innerHTML = html;
                }
            };
            xhr.send();
        }
        
        // jQuery AJAX
        function loadDataJQuery() {
            $.ajax({
                url: 'api.php',
                type: 'GET',
                dataType: 'json',
                success: function(data) {
                    console.log(data);
                    // 更新页面
                    var html = '';
                    data.data.forEach(function(item) {
                        html += '<div>' + item.title + '</div>';
                    });
                    $('#result').html(html);
                },
                error: function(xhr, status, error) {
                    console.error(error);
                }
            });
        }
        
        // Fetch API
        function loadDataFetch() {
            fetch('api.php')
                .then(response => response.json())
                .then(data => {
                    console.log(data);
                    // 更新页面
                    let html = '';
                    data.data.forEach(item => {
                        html += '<div>' + item.title + '</div>';
                    });
                    document.getElementById('result').innerHTML = html;
                })
                .catch(error => console.error(error));
        }
    </script>
</head>
<body>
    <button onclick="loadData()">加载数据</button>
    <div id="result"></div>
    
    <script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
</body>
</html>

后端处理 AJAX 请求 ​

php
<?php
header('Content-Type: application/json; charset=utf-8');
header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Methods: GET, POST, PUT, DELETE');
header('Access-Control-Allow-Headers: Content-Type');

// 连接数据库
$conn = mysqli_connect("localhost", "root", "", "myDB");

// 处理 GET 请求
if ($_SERVER['REQUEST_METHOD'] === 'GET') {
    $sql = "SELECT * FROM articles";
    $result = mysqli_query($conn, $sql);
    $data = [];
    while ($row = mysqli_fetch_assoc($result)) {
        $data[] = $row;
    }
    echo json_encode([
        'code' => 200,
        'message' => 'success',
        'data' => $data
    ]);
}

// 处理 POST 请求
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $input = json_decode(file_get_contents('php://input'), true);
    
    $title = mysqli_real_escape_string($conn, $input['title']);
    $content = mysqli_real_escape_string($conn, $input['content']);
    
    $sql = "INSERT INTO articles (title, content) VALUES ('$title', '$content')";
    if (mysqli_query($conn, $sql)) {
        echo json_encode([
            'code' => 200,
            'message' => '添加成功'
        ]);
    } else {
        echo json_encode([
            'code' => 500,
            'message' => '添加失败'
        ]);
    }
}

mysqli_close($conn);
?>

小结 ​

通过本章的学习，你掌握了 PHP 开发中常用的功能实现，包括发送邮件、生成验证码、分页功能、API 接口开发和 AJAX 交互。这些功能在 Web 开发中非常常见，掌握它们的实现方法对于开发完整的 Web 应用非常重要。在实际开发中，你可以根据项目需求选择合适的实现方式，并注意安全性和性能优化。

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