api/app/Http/Middleware/Localization.php

<?php

namespace App\Http\Middleware;

use Closure;
use Illuminate\Support\Facades\App;
use Illuminate\Support\Facades\Session;

class Localization
{
    // 支持的语种
    protected $supportedLocales = ['zh_CN', 'zh_TW', 'en', 'ja', 'ko'];

    public function handle($request, Closure $next)
    {
        $locale = $this->getLocaleFromRequest($request);

        // 设置应用语言环境
        App::setLocale('zh_CN');

        // 可选：将当前语言添加到响应头中
        $response = $next($request);
        $response->header('Content-Language', $locale);

        return $response;
    }

    /**
     * 从请求中获取语言设置
     */
    protected function getLocaleFromRequest($request)
    {
        // 1. 优先从 Headers 获取
        $locale = $request->header('lang') ??
            $request->header('x-lang') ??
            $request->header('accept-language');

        // 2. 如果是 accept-language，提取主要语言
        if ($locale && str_contains($locale, ',')) {
            $locale = strtok($locale, ',');
        }

        // 3. 规范化语言代码
        $locale = $this->normalizeLocale($locale);

        // 4. 验证是否为支持的语种
        if (!in_array($locale, $this->supportedLocales)) {
            return config('app.fallback_locale', 'en');
        }

        return $locale;
    }

    /**
     * 规范化语言代码
     */
    protected function normalizeLocale($locale)
    {
        if (!$locale) {
            return config('app.locale', 'zh_CN');
        }

        // 处理简写
        $localeMap = [
            'zh' => 'zh_CN',
            'zh-CN' => 'zh_CN',
            'zh-cn' => 'zh_CN',
            'zh-Hans' => 'zh_CN',
            'zh-TW' => 'zh_TW',
            'zh-Hant' => 'zh_TW',
            'en-US' => 'en',
            'en-GB' => 'en',
            'ja-JP' => 'ja',
            'ko-KR' => 'ko',
            'chinese_simplified' => 'zh_CN',
            'Chinese_simplified' => 'zh_CN',
            'Chinese_Simplified' => 'zh_CN',
            'ChineseSimplified' => 'zh_CN',
            'chineseSimplified' => 'zh_CN',
            'chinese_traditional' => 'zh_TW',
            'Chinese_traditional' => 'zh_TW',
            'Chinese_Traditional' => 'zh_TW',
            'ChineseTraditional' => 'zh_TW',
            'chineseTraditional' => 'zh_TW',
            'english' => 'en',
            'English' => 'en',
            'japanese' => 'ja',
            'Japanese' => 'ja',
            'korean' => 'ko',
            'Korean' => 'ko'

        ];


        if (isset($localeMap[$locale])) {
            return $localeMap[$locale];
        }

        // 保持原有格式或转换为下划线格式
        return $locale;
    }
}