这是新的和改进的非反射版本

#services.yml
acme_app.dynamic_connection:
    class: %acme.dynamic_doctrine_connection.class%
    calls:
        - [setDoctrineConnection, [@doctrine.dbal.default_connection]]


<?php

namespace Acme\Bundle\AppBundle;

use Doctrine\DBAL\Connection;
use Symfony\Component\HttpKernel\Exception\ServiceUnavailableHttpException;
use Exception;

class DynamicDoctrineConnection
{
    /**
     * @var Connection
     */
    private $connection;

    /**
     * Sets the DB Name prefix to use when selecting the database to connect to
     *
     * @param  Connection       $connection
     * @return SiteDbConnection $this
     */
    public function setDoctrineConnection(Connection $connection)
    {
        $this->connection = $connection;

        return $this;
    }

    public function setUpAppConnection()
    {
        if ($this->request->attributes->has('appId')) {
            $connection = $this->connection;
            $params     = $this->connection->getParams();

            // we also check if the current connection needs to be closed based on various things
            // have left that part in for information here
            // $appId changed from that in the connection?
            // if ($connection->isConnected()) {
            //     $connection->close();
            // }

            // Set default DB connection using appId
            //$params['host']   = $someHost;
            $params['dbname'] = 'Acme_App'.$this->request->attributes->get('appId');

            // Set up the parameters for the parent
            $connection->__construct(
                $params, $connection->getDriver(), $connection->getConfiguration(),
                $connection->getEventManager()
            );

            try {
                $connection->connect();
            } catch (Exception $e) {
                // log and handle exception
            }
        }

        return $this;
    }
}