private static void RecoveryObjectReference(string bundleName)
    {
        BundleReference br = null;

        if (!_bundleReferenceList.TryGetValue(bundleName, out br))
        {
            return;
        }

        // bundle引用为0
        if (br.assetBundle)
        {
            Debug.Log("assetBundle Unload(true) " + bundleName);
            br.assetBundle.Unload(true);
        }

        _bundleReferenceList.Remove(bundleName);
        br.Clear();
        _freeBundleReferenceList.Add(br);
    }