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app/Core/Db.php

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+<?php
+namespace Core;
+
+/**
+ * 数据库连接（MySQL PDO 单例；文件路径模式）
+ */
+class Db
+{
+    private static $pdo = null;
+
+    public static function driver(): string
+    {
+        return App::config('app.driver', 'file');
+    }
+
+    public static function pdo(): \PDO
+    {
+        if (self::$pdo === null) {
+            $c = App::config('db.mysql');
+            $dsn = "mysql:host={$c['host']};port={$c['port']};dbname={$c['dbname']};charset={$c['charset']}";
+            self::$pdo = new \PDO($dsn, $c['user'], $c['pass'], [
+                \PDO::ATTR_ERRMODE          => \PDO::ERRMODE_EXCEPTION,
+                \PDO::ATTR_DEFAULT_FETCH_MODE => \PDO::FETCH_ASSOC,
+                \PDO::ATTR_EMULATE_PREPARES   => false,
+            ]);
+        }
+        return self::$pdo;
+    }
+
+    public static function fileDir(): string
+    {
+        $dir = App::config('db.file.dir');
+        if (!is_dir($dir)) mkdir($dir, 0755, true);
+        return $dir;
+    }
+
+    public static function query(string $sql, array $params = []): \PDOStatement
+    {
+        $st = self::pdo()->prepare($sql);
+        $st->execute($params);
+        return $st;
+    }
+}