PHP マイクロサービスでデータベース接続とクエリを管理する方法

$dsn = 'mysql:host=localhost;dbname=test;charset=utf8';
$username = 'root';
$password = '';

try {
    $db = new PDO($dsn, $username, $password);
    $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch (PDOException $e) {
    echo '连接数据库失败：' . $e->getMessage();
}

class Database
{
    private static $instance;
    private $db;

    private function __construct()
    {
        $dsn = 'mysql:host=localhost;dbname=test;charset=utf8';
        $username = 'root';
        $password = '';

        try {
            $this->db = new PDO($dsn, $username, $password);
            $this->db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        } catch (PDOException $e) {
            echo '连接数据库失败：' . $e->getMessage();
        }
    }

    public static function getInstance()
    {
        if (!self::$instance) {
            self::$instance = new self();
        }

        return self::$instance;
    }

    public function getDB()
    {
        return $this->db;
    }
}

// 使用方式
$db = Database::getInstance()->getDB();

$username = 'admin';
$password = '123456';

// 预处理语句
$stmt = $db->prepare('SELECT * FROM users WHERE username = :username AND password = :password');
$stmt->bindParam(':username', $username);
$stmt->bindParam(':password', $password);

// 执行查询
$stmt->execute();

// 获取查询结果
$result = $stmt->fetchAll(PDO::FETCH_ASSOC);

// 处理查询结果
foreach ($result as $row) {
    // ...
}