mtb_dcatadmin_plus/app/Admin/Controllers/LanguageController.php

<?php
namespace App\Admin\Controllers;

use App\Http\Controllers\Controller;
use Illuminate\Http\Request;
class LanguageController extends Controller
{

    public function index(Request $request)
    {
        return $this->switchLanguage($request);
    }


    /**
     * 切换语言并修改 app.locale
     *
     * @param Request $request
     * @return \Illuminate\Http\RedirectResponse
     */
    public function switchLanguage(Request $request)
    {

        // 从 URL 参数中获取语言，默认为 'en'
        $lang = $request->input('lang', 'en');

        if (!$lang)
        {
            abort(404);
        }
        // 验证是否是支持的语言
        if (!in_array($lang, ['en', 'zh_CN'])) {
            abort(404);
        }
        switchLanguage($lang);
        return response()->json(['success' => true, 'lang' => $lang]);
    }
}