已经发布的实训，无法撤销发布

app/controllers/shixuns_controller.rb

@@ -745,6 +745,7 @@ class ShixunsController < ApplicationController
 
 	# 撤销发布
 	def cancel_publish
+		tip_exception("实训已经发布，无法撤销") if @shixun.status == 2
 		apply = ApplyAction.where(:container_type => "ApplyShixun", :container_id => @shixun.id).order("created_at desc").first
 		if apply && apply.status == 0
 			apply.update_attribute(:status, 3)