#多语言

// config/app.php
'locale' => env('APP_LOCALE', 'en'),
'fallback_locale' => env('APP_FALLBACK_LOCALE', 'en'),

<?php
// lang/zh/user.php
return [
    'not_login'           => '请先登录',
    'login_success'       => '登录成功',
    'login_error'         => '登录失败，用户名或者密码错误！',
    'logout_success'      => '退出成功',
    'old_password_error'  => '旧密码错误',
    'user_not_exist'      => '用户不存在，请先注册',
    'user_is_disabled'    => '用户已被禁用',
];

<?php
// lang/en/user.php
return [
    'not_login'           => 'Please log in first',
    'login_success'       => 'Login Success',
    'login_error'         => 'Login Error, Please check your username and password',
    'logout_success'      => 'Logout Success',
    'old_password_error'  => 'Old password error',
    'user_not_exist'      => 'User does not exist, please register first',
    'user_is_disabled'    => 'User is disabled',
];

// lang/zh/system.php
return [
    'file' => [
        'image'           => '图片',
        'audio'           => '音频',
        'video'           => '视频',
        'upload_failed'   => '上传失败',
        'not_found'       => '文件不存在',
    ],
    'error' => [
        'no_permission'  => '对不起，你暂时没有该权限，请联系管理员',
        'route_not_exist' => '路由不存在',
    ],
    'data_not_exist' => '数据不存在',
];

// 使用
__('system.file.upload_failed');   // "上传失败"
__('system.error.no_permission');  // "对不起，你暂时没有该权限..."

// modules/Common/Middlewares/LanguageMiddleware.php
class LanguageMiddleware
{
    protected array $supportedLanguages = [
        'en' => 'en',
        'zh' => 'zh',
        'jp' => 'ja',
    ];

    public function handle(Request $request, Closure $next)
    {
        $locale = $this->getLocale($request);
        App::setLocale($locale);
        return $next($request);
    }

    protected function getLocale(Request $request): string
    {
        // 优先级 1: URL 参数 ?lang=en
        if ($request->has('lang') && $this->isSupported($request->get('lang'))) {
            return $request->get('lang');
        }
        // 优先级 2: User-Language 请求头（前端 Axios 自动发送）
        $browserLocale = $request->header('User-Language');
        if ($browserLocale && $this->isSupported($browserLocale)) {
            return $browserLocale;
        }
        // 优先级 3: Session 中存储的语言
        if (Session::has('locale') && $this->isSupported(Session::get('locale'))) {
            return Session::get('locale');
        }
        // 优先级 4: config('app.locale') 默认语言
        return config('app.locale', 'zh');
    }
}

$response->headers->set(
    'Access-Control-Allow-Headers',
    'Content-Type, Authorization, X-Requested-With, User-Language'
);

use App\Http\Controllers\Controller;

class IndexController extends Controller
{
    public function login(Request $request)
    {
        if ($valid) {
            return response()->json([
                'success' => true,
                'msg' => __('user.login_success'),
            ]);
        }
        return response()->json([
            'success' => false,
            'msg' => __('user.login_error'),
        ]);
    }
}

// lang/ja/user.php
return [
    'not_login'      => 'まずログインしてください',
    'login_success'  => 'ログイン成功',
    'login_error'    => 'ログイン失敗、ユーザー名かパスワードが間違っています',
    'logout_success' => 'ログアウト成功',
];

// LanguageMiddleware.php
protected array $supportedLanguages = [
    'en' => 'en',
    'zh' => 'zh',
    'ja' => 'ja',    // 新增，key 为前端传递的语言码
];