diff --git a/app/common.php b/app/common.php
index ee5052f..1caa6d3 100644
--- a/app/common.php
+++ b/app/common.php
@@ -53,4 +53,22 @@ function checkToken($token): array
         $status['msg'] = "未知错误";
         return $status;
     }
+}
+
+/**
+ * 获取随机用户命
+ * @param $length
+ * @return string
+ */
+function generate_random_str($length = 8) {
+    $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
+    $username = '';
+
+    $maxIndex = strlen($characters) - 1;
+    for ($i = 0; $i < $length; $i++) {
+        $randomIndex = mt_rand(0, $maxIndex);
+        $username .= $characters[$randomIndex];
+    }
+
+    return $username;
 }
\ No newline at end of file
diff --git a/app/model/User.php b/app/model/User.php
index f459bbd..ed6833d 100644
--- a/app/model/User.php
+++ b/app/model/User.php
@@ -27,7 +27,7 @@ class User extends Model
         $password = $this->generateHashedPassword($data['password'], $salt);
 
         $this->save([
-            'username' => $this->generateRandomUsername(),
+            'username' => generate_random_str(),
             'password' => $password,
             'salt' => $salt,
             'phone' => $data['phone'],
@@ -189,7 +189,7 @@ class User extends Model
      */
     private function generateSalt()
     {
-        return $this->generateRandomUsername(6);
+        return generate_random_str(6);
     }
 
     /**
@@ -202,22 +202,4 @@ class User extends Model
     {
         return md5(md5($password) . md5($salt));
     }
-
-    /**
-     * 获取随机用户命
-     * @param $length
-     * @return string
-     */
-    private function generateRandomUsername($length = 8) {
-        $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
-        $username = '';
-
-        $maxIndex = strlen($characters) - 1;
-        for ($i = 0; $i < $length; $i++) {
-            $randomIndex = mt_rand(0, $maxIndex);
-            $username .= $characters[$randomIndex];
-        }
-
-        return $username;
-    }
 }
\ No newline at end of file