文档参考：

$this->getDefault()

获取默认服务器连接,返回\Doctrine\DBAL\Connection对象

$this->getRead($name = null)

$this->getWrite($name = null)

获取写服务器连接，若name不填，随机读取。

$this->getAllRead()

$this->getAllWrite()

$this->querySql($sql, $type, $name = null)

具体业务中使用：

namespace src\Service\User\Dao\Impl;
use Dao;
use src\Service\User\Dao\UserDao;
class UserDaoImpl extends Dao implements UserDao
    protected $table = "user";
    public function getUser($id)
    {
        $queryBuilder = $this->getDefault()->createQueryBuilder();
        $queryBuilder
            ->select("*")
            ->from($this->table)
            ->setParameter(0, $id);
        return $queryBuilder->execute()->fetch();
    }
    public function addUser($user)
    {
        $conn = $this->getDefault();
        $affected = $conn->insert($this->table, $user);
        if ($affected <= 0) {
        }
        return $conn->lastInsertId();
    }
    {
        $queryBuilder = $this->getDefault()->createQueryBuilder();
        $queryBuilder
            ->select("*")
            ->from($this->table)
            ->where('mobile = ?')
            ->setParameter(0, $mobile);
        return $queryBuilder->execute()->fetch();
    }
    public function updateUserPassword($userId, $password)
    {
        return $this->getDefault()->update($this->table, ['password' => $password], ['id' => $userId]);