[增添]添加了datasource的setting数据库以及默认值

vendor/symfony/mailer/Messenger/MessageHandler.php

@@ -0,0 +1,33 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Mailer\Messenger;
+
+use Symfony\Component\Mailer\SentMessage;
+use Symfony\Component\Mailer\Transport\TransportInterface;
+
+/**
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+class MessageHandler
+{
+    private TransportInterface $transport;
+
+    public function __construct(TransportInterface $transport)
+    {
+        $this->transport = $transport;
+    }
+
+    public function __invoke(SendEmailMessage $message): ?SentMessage
+    {
+        return $this->transport->send($message->getMessage(), $message->getEnvelope());
+    }
+}