diff --git a/README.md b/README.md
index dd2a666cea24777123fb1515ce027edc6f5676a4..fc1056363463656cf204cdc0f3ed4a35faf99c9d 100644
--- a/README.md
+++ b/README.md
@@ -1,31 +1,31 @@
-#Teaching interactive web platform
-#教学互动平台
-
-* 本系统的主要目标是实现网上互动教学功能，在总体上采用B/S架构(Browser/Server)，教师通过浏览器在该平台发布课程资料和作业等信息，数据资料经处理后存储在云端，学生注册后可提交作业，在线浏览教师发布的资料，以及在线交流学习心得，和教师答疑互动。
-* 本系统的主要特色是针对移动设备的响应式布局，使得该平台不再局限在PC上，教师和学生使用随身携带的平板或手机登录网站，都可以获得较好的用户体验。因而大大提高了教学平台的便携能力，进一步提升该平台的互动的及时性。
-* 本项目为本人的个人毕设项目：
-
-> * 本项目采用 [GNU GPL v3](http://opensource.org/licenses/GPL-3.0)许可证授权,欢迎大家在这个基础上进行改进并分享。
-> * GNU GPL v3许可证:[https://www.gnu.org/licenses/gpl-3.0.txt](https://www.gnu.org/licenses/gpl-3.0.txt)
-
----
-### 本项目演示地址:
-* [GitChina演示平台](http://teachtest.oschina.mopaas.com/)
-
----
-### 本项目源码:
-
-* [GitHub](https://github.com/quericy/Teaching-interactive-web-platform)
-* [GitChina](https://git.oschina.net/quericy/Teaching-interactive-web-platform)
-
----
-###数据库说明:
-
-* 数据库位于项目的application/config/目录下，请导入teaching_interactive.sql到mysql数据库中，并配置database.php对应的数据库信息
-* 后台教师登录初始用户名密码均为admin
-
----
-欢迎交流与探讨:
-
-* Blog: [quericy.me](http://quericy.me)
-* GitHub: [https://github.com/quericy](https://github.com/quericy)
+#Teaching interactive web platform
+#教学互动平台
+
+* 本系统的主要目标是实现网上互动教学功能，在总体上采用B/S架构(Browser/Server)，教师通过浏览器在该平台发布课程资料和作业等信息，数据资料经处理后存储在云端，学生注册后可提交作业，在线浏览教师发布的资料，以及在线交流学习心得，和教师答疑互动。
+* 本系统的主要特色是针对移动设备的响应式布局，使得该平台不再局限在PC上，教师和学生使用随身携带的平板或手机登录网站，都可以获得较好的用户体验。因而大大提高了教学平台的便携能力，进一步提升该平台的互动的及时性。
+* 本项目为本人的个人毕设项目：
+
+> * 本项目采用 [GNU GPL v3](http://opensource.org/licenses/GPL-3.0)许可证授权,欢迎大家在这个基础上进行改进并分享。
+> * GNU GPL v3许可证:[https://www.gnu.org/licenses/gpl-3.0.txt](https://www.gnu.org/licenses/gpl-3.0.txt)
+
+---
+### 本项目演示地址:
+* [GitChina演示平台](http://teachtest.butterfly.mopaasapp.com/)
+
+---
+### 本项目源码:
+
+* [GitHub](https://github.com/quericy/Teaching-interactive-web-platform)
+* [GitChina](https://git.oschina.net/quericy/Teaching-interactive-web-platform)
+
+---
+###数据库说明:
+
+* 数据库位于项目的application/config/目录下，请导入teaching_interactive.sql到mysql数据库中，并配置database.php对应的数据库信息
+* 后台教师登录初始用户名密码均为admin
+
+---
+欢迎交流与探讨:
+
+* Blog: [quericy.me](https://quericy.me)
+* GitHub: [https://github.com/quericy](https://github.com/quericy)
diff --git a/application/config/database.php b/application/config/database.php
index 60997c440e7db765eb08a8cfd9534affab8074f5..da9c7ed6514574db6a4133a12ddbdbf785df7963 100644
--- a/application/config/database.php
+++ b/application/config/database.php
@@ -1,4 +1,4 @@
-<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');
+<?php if (!defined('BASEPATH')) exit('No direct script access allowed');
 /*
 | -------------------------------------------------------------------
 | DATABASE CONNECTIVITY SETTINGS
@@ -47,40 +47,24 @@
 
 $active_group = 'default';
 $active_record = TRUE;
-//数据库临时切换
-if($_SERVER['SERVER_NAME']=='teachtest.oschina.mopaas.com'){//演示平台数据库
-	$db['default']['hostname'] = '10.4.26.93';
-	$db['default']['username'] = 'ulcVC3jQh2z1V';
-	$db['default']['password'] = 'p78s7qRXI7US1';
-	$db['default']['database'] = 'd5fb6626cd2934111b2b52b6ab6029beb';
-	$db['default']['dbdriver'] = 'mysql';
-	$db['default']['dbprefix'] = 'table_';
-	$db['default']['pconnect'] = TRUE;
-	$db['default']['db_debug'] = TRUE;
-	$db['default']['cache_on'] = FALSE;
-	$db['default']['cachedir'] = '';
-	$db['default']['char_set'] = 'utf8';
-	$db['default']['dbcollat'] = 'utf8_general_ci';
-	$db['default']['swap_pre'] = '';
-	$db['default']['autoinit'] = TRUE;
-	$db['default']['stricton'] = FALSE;
-}else{
-	$db['default']['hostname'] = 'localhost';
-	$db['default']['username'] = 'root';
-	$db['default']['password'] = 'root';
-	$db['default']['database'] = 'teaching_interactive';
-	$db['default']['dbdriver'] = 'mysql';
-	$db['default']['dbprefix'] = 'table_';
-	$db['default']['pconnect'] = TRUE;
-	$db['default']['db_debug'] = TRUE;
-	$db['default']['cache_on'] = FALSE;
-	$db['default']['cachedir'] = '';
-	$db['default']['char_set'] = 'utf8';
-	$db['default']['dbcollat'] = 'utf8_general_ci';
-	$db['default']['swap_pre'] = '';
-	$db['default']['autoinit'] = TRUE;
-	$db['default']['stricton'] = FALSE;
-}
+//数据库切换
+$db['default']['hostname'] = getenv('DB_HOST') ?: 'localhost';
+$db['default']['port'] = getenv('DB_PORT') ?: '3306';
+$db['default']['username'] = getenv('DB_USER') ?: 'root';
+$db['default']['password'] = getenv('DB_PASS') ?: 'root';
+$db['default']['database'] = getenv('DB_DATABASE') ?: 'teaching_interactive';
+$db['default']['dbdriver'] = getenv('DB_DRIVER') ?: 'mysql';
+$db['default']['dbprefix'] = getenv('DB_PREFIX') ?: 'table_';
+$db['default']['pconnect'] = TRUE;
+$db['default']['db_debug'] = TRUE;
+$db['default']['cache_on'] = FALSE;
+$db['default']['cachedir'] = '';
+$db['default']['char_set'] = 'utf8';
+$db['default']['dbcollat'] = 'utf8_general_ci';
+$db['default']['swap_pre'] = '';
+$db['default']['autoinit'] = TRUE;
+$db['default']['stricton'] = FALSE;
+
 
 
 
diff --git a/system/core/Security.php b/system/core/Security.php
index efa2df922441484bee05ce50645928a90fd1f4de..04beca56eaf23f03a2dff835d39583f19601235f 100644
--- a/system/core/Security.php
+++ b/system/core/Security.php
@@ -508,9 +508,14 @@ class CI_Security {
 			return $str;
 		}
 
-		$str = html_entity_decode($str, ENT_COMPAT, $charset);
-		$str = preg_replace('~&#x(0*[0-9a-f]{2,5})~ei', 'chr(hexdec("\\1"))', $str);
-		return preg_replace('~&#([0-9]{2,4})~e', 'chr(\\1)', $str);
+        if(version_compare(PHP_VERSION,5.5,'>=')){
+            $str = preg_replace_callback('~&#x(0*[0-9a-f]{2,5})~i', function(){return chr(hexdec('\\1'));}, $str, -1, $matches);
+            $str = preg_replace_callback('~&#([0-9]{2,4})~', function(){return chr('\\1');}, $str, -1, $matches1);
+        }else{
+            $str = preg_replace('~&#x(0*[0-9a-f]{2,5})~ei', 'chr(hexdec("\\1"))', $str, -1, $matches);
+            $str = preg_replace('~&#([0-9]{2,4})~e', 'chr(\\1)', $str, -1, $matches1);
+        }
+		return $str;
 	}
 
 	// --------------------------------------------------------------------