修改第一次打包下载成功，后面打包下载失败的BUG

app/controllers/zipdown_controller.rb

@@ -72,7 +72,7 @@ class ZipdownController < ApplicationController
     homeattach.attachments.each do |attach|
       homeworks_attach_path << attach.diskfile#.to_s.slice((length+1)..-1)
     end
-    zipping("#{homeattach.user.name}_#{homeattach.user.user_extensions.student_id}.zip", homeworks_attach_path, OUTPUT_FOLDER, true)
+    zipping("#{Time.now.to_i.to_s}_#{homeattach.user.name}_#{homeattach.user.user_extensions.student_id}.zip", homeworks_attach_path, OUTPUT_FOLDER, true)
   end
 
 
@@ -81,7 +81,7 @@ class ZipdownController < ApplicationController
     ic = Iconv.new('GBK//IGNORE', 'UTF-8//IGNORE')
     input_filename = files_paths
 
-    rename_zipfile = zip_name_refer ||= "homework.zip"
+    rename_zipfile = zip_name_refer ||= "#{Time.now.to_i.to_s}.zip"
     zipfile_name = "#{output_path}/#{rename_zipfile}"
 
     Dir.mkdir(File.dirname(zipfile_name)) unless File.exist?(File.dirname(zipfile_name))