更新2

app/admin/validate/UserCheck.php

@@ -0,0 +1,26 @@
+<?php
+/**
+ * @copyright Copyright (c) 2021 勾股工作室
+ * @license https://opensource.org/licenses/Apache-2.0
+ * @link https://www.gougucms.com
+ */
+
+namespace app\admin\validate;
+
+use think\Validate;
+
+class UserCheck extends Validate
+{
+    protected $rule = [
+        'username' => 'require',
+        'password' => 'require',
+        'captcha' => 'require|captcha',
+    ];
+
+    protected $message = [
+        'username.require' => '用户名不能为空',
+        'password.require' => '密码不能为空',
+        'captcha.require' => '验证码不能为空',
+        'captcha.captcha' => '验证码不正确',
+    ];
+}