diff --git a/app/controllers/shixuns_controller.rb b/app/controllers/shixuns_controller.rb
index d4f9bd3c8..ac26b740c 100644
--- a/app/controllers/shixuns_controller.rb
+++ b/app/controllers/shixuns_controller.rb
@@ -1096,4 +1096,13 @@ private
 		end
 	end
 
+	def file_ext(file_name)
+		ext = ''
+		exts = file_name.split(".")
+		if exts.size > 1
+			ext = ".#{exts.last}"
+		end
+		ext
+	end
+
 end