water/server/plugin/saiadmin/app/middleware/CrossDomain.php

<?php
// +----------------------------------------------------------------------
// | saiadmin [ saiadmin快速开发框架 ]
// +----------------------------------------------------------------------
// | Author: sai <1430792918@qq.com>
// +----------------------------------------------------------------------
namespace plugin\saiadmin\app\middleware;

use Webman\Http\Request;
use Webman\Http\Response;
use Webman\MiddlewareInterface;

/**
 * 跨域中间件
 */
class CrossDomain implements MiddlewareInterface
{
    public function process(Request $request, callable $handler) : Response
    {
        // Mini API owns its explicit-origin CORS policy; leave the existing admin policy unchanged.
        if (\app\miniapi\http\ApiResponse::owns($request)) return $handler($request);
        // 如果是options请求则返回一个空响应，否则继续向洋葱芯穿越，并得到一个响应
        $response = $request->method() == 'OPTIONS' ? response('') : $handler($request);

        // 给响应添加跨域相关的http头
        $response->withHeaders([
            'Access-Control-Allow-Credentials' => 'true',
            'Access-Control-Allow-Origin' => $request->header('origin', '*'),
            'Access-Control-Allow-Methods' => $request->header('access-control-request-method', '*'),
            'Access-Control-Allow-Headers' => $request->header('access-control-request-headers', '*'),
        ]);

        return $response;
    }
}