How to set AssetBundleName from editor scripts.

AssetBundleNameGenerator.cs

public class AssetBundleNameGenerator
{
    [MenuItem("AssetBundles/Set XXX")]
    public static void SetXXX()
    {
        foreach (var file in Directory
            .GetFiles("Assets/XXX/XXX/",
                "*.xxx", SearchOption.TopDirectoryOnly))
        {
            var importer = AssetImporter.GetAtPath(file);
            var fileNameWithoutExt = Path.GetFileNameWithoutExtension(file);
            var assetBundleName = "xxx/xxx/" + fileNameWithoutExt;
            if (importer.assetBundleName == assetBundleName)
            {
                continue;
            }

            importer.assetBundleName = assetBundleName;
            importer.SaveAndReimport();
        }
    }
}