diff --git a/composer.json b/composer.json
index 0f1effe..2ab0aa6 100644
--- a/composer.json
+++ b/composer.json
@@ -20,7 +20,7 @@
   ],
   "homepage": "https://www.dtapp.net",
   "require": {
-    "php": ">=7.1.0",
+    "php": ">=7.2",
     "ext-gd": "*",
     "ext-libxml": "*",
     "ext-json": "*",
@@ -28,7 +28,8 @@
     "ext-zip": "*",
     "topthink/framework": "^6.0.0",
     "topthink/think-orm": "^2.0",
-    "liguangchun/ip": "^1.1"
+    "liguangchun/ip": "^1.1",
+    "ext-bcmath": "*"
   },
   "autoload": {
     "files": [
diff --git a/src/common.php b/src/common.php
index af8c08c..6f785d0 100644
--- a/src/common.php
+++ b/src/common.php
@@ -60,3 +60,33 @@ if (!function_exists('get_ip')) {
         return $ip;
     }
 }
+
+if (!function_exists('getEnid')) {
+
+    /**
+     * 10进制转化36进制
+     * https://blog.csdn.net/zhangchb/article/details/78855083
+     * @param int $format
+     * @return mixed|string
+     */
+    function getEnid($format = 8)
+    {
+        $dic = array(
+            0 => '0', 1 => '1', 2 => '2', 3 => '3', 4 => '4', 5 => '5', 6 => '6', 7 => '7', 8 => '8', 9 => '9',
+            10 => 'A', 11 => 'B', 12 => 'C', 13 => 'D', 14 => 'E', 15 => 'F', 16 => 'G', 17 => 'H', 18 => 'I',
+            19 => 'J', 20 => 'K', 21 => 'L', 22 => 'M', 23 => 'N', 24 => 'O', 25 => 'P', 26 => 'Q', 27 => 'R',
+            28 => 'S', 29 => 'T', 30 => 'U', 31 => 'V', 32 => 'W', 33 => 'X', 34 => 'Y', 35 => 'Z'
+        );
+        $int = session('user.id');
+        $arr = array();
+        $loop = true;
+        while ($loop) {
+            $arr[] = $dic[bcmod($int, 36)];
+            $int = floor(bcdiv($int, 36));
+            if ($int == 0) $loop = false;
+        }
+        array_pad($arr, $format, $dic[0]);
+        return implode('', array_reverse($arr));
+    }
+}
+
diff --git a/src/session/Mysql.php b/src/session/Mysql.php
index 9d5e654..96211d2 100644
--- a/src/session/Mysql.php
+++ b/src/session/Mysql.php
@@ -30,10 +30,20 @@ use think\facade\Db;
  */
 class Mysql implements SessionHandlerInterface
 {
-    protected $table_name = 'think_session'; // 表名
+    /**
+     * 表名
+     * @var string
+     */
+    protected $table_name = 'think_session';
+
+    /**
+     * session_expire Session有效期 单位：秒
+     * session_prefix Session前缀
+     * @var array
+     */
     protected $config = [
-        'session_expire' => 1800,           // Session有效期 单位：秒
-        'session_prefix' => 'think_',       // Session前缀
+        'session_expire' => 1800,
+        'session_prefix' => 'think_'
     ];
 
     /**