neiyou_user_web/app/Http/Middleware/SetLocale.php

<?php

namespace App\Http\Middleware;

use Closure;
use Illuminate\Http\Request;
use Session;

class SetLocale {
	/**
	 * 变更语言
	 *
	 * @param  Request  $request
	 * @param  Closure  $next
	 *
	 * @return mixed
	 */
	public function handle($request, Closure $next) {
		if(Session::has('locale')){
			app()->setLocale(Session::get('locale'));
		}

		if($request->query('locale')){
			Session::put('locale', $request->query('locale'));
			app()->setLocale($request->query('locale'));
		}

		return $next($request);
	}

}