Add Article service and DAO with criteria-based search functionality

hibernate-project/src/main/java/com/humanbooster/service/ArticleService.java

@@ -4,6 +4,7 @@ import com.humanbooster.dao.ArticleDao;
 import com.humanbooster.model.Article;
 
 import java.util.List;
+import java.util.Optional;
 
 public class ArticleService {
 
@@ -40,4 +41,8 @@ public class ArticleService {
     public Article findArticleByTitle(String title) {
         return articleDao.findByTitle(title);
     }
+
+    public List<Article> findArticlesByCriteria(String keyword, Long authorId) {
+        return articleDao.findByCriteria(keyword, authorId);
+    }
 }