你看看 Illuminate\Auth\Passwords\PasswordBrokerManager 的 broker 方法:
public function broker($name = null)
{
$name = $name ?: $this->getDefaultDriver();
return isset($this->brokers[$name])
? $this->brokers[$name]
: $this->brokers[$name] = $this->resolve($name);
}
getDefaultDriver :
public function getDefaultDriver()
{
return $this->app['config']['auth.defaults.passwords'];
}