import com.liferay.portal.kernel.search.Indexer
import com.liferay.portal.kernel.search.IndexerRegistryUtil
import com.liferay.portlet.journal.model.JournalArticle
import com.liferay.portlet.journal.service.JournalArticleLocalServiceUtil

Indexer jaIndexer = IndexerRegistryUtil.getIndexer(JournalArticle.class);

def articles = JournalArticleLocalServiceUtil.getArticles()
articles.each { JournalArticle item ->
    jaIndexer.reindex(JournalArticle.class.getName(), item.getResourcePrimKey());
}