diff --git a/backend/modules/shop/logic/ShopManager.php b/backend/modules/shop/logic/ShopManager.php
new file mode 100644
index 0000000..a463a05
--- /dev/null
+++ b/backend/modules/shop/logic/ShopManager.php
@@ -0,0 +1,36 @@
+<?php
+namespace backend\modules\shop\logic;
+
+use Yii;
+use yii\base\Exception;
+
+class CommonManager
+{
+    //单位类型
+    const UNIT_TYPE_WEIGHT = 1; //重量
+    const UNIT_TYPE_MONEY = 2;  //金额
+    const UNIT_TYPE_ITEM = 3;   //件
+
+    /**
+     * @param $type
+     * @param $value
+     * @return int
+     * 比例转换
+     */
+    public static function proportionalConversion($type, $value)
+    {
+        switch ($type) {
+            case self::UNIT_TYPE_WEIGHT:
+                return 1000;
+                break;
+            case self::UNIT_TYPE_MONEY:
+                return 100;
+                break;
+            case self::UNIT_TYPE_ITEM:
+                return 1;
+                break;
+            default:
+                return 1;
+        }
+    }
+}
\ No newline at end of file