​
在路由处加上allowCrossDomain()就可以了。

跨域请求一般会发送一条OPTIONS的请求，一旦设置了跨域请求的话，不需要自己定义OPTIONS请求的路由，系统会自动加上。

跨域请求系统会默认带上一些Header，包括：
Access-Control-Allow-Origin:*
Access-Control-Allow-Methods:GET, POST, PATCH, PUT, DELETE
Access-Control-Allow-Headers:Authorization, Content-Type, If-Match, If-Modified-Since, If-None-Match, If-Unmodified-Since, X-Requested-With

第二种方法：在入口文件（index.php）加入防跨域代码：

header('Content-Type: text/html;charset=utf-8');header('Access-Control-Allow-Origin:*'); header('Access-Control-Allow-Methods:POST,GET,OPTIONS,DELETE');header('Access-Control-Allow-Credentials: true');header('Access-Control-Allow-Headers: Content-Type,Content-Length,Accept-Encoding,X-Requested-with, Origin');

第三种方法：

在这里可以使用tp6的前置中间件

首先开启中间件的文件配置

然后创建一个中间件文件

最后配置

<?php/** * Created by PhpStorm. * User: Administrator * Date: 2021/4/9 * Time: 17:51 */declare (strict_types = 1);namespace app\middleware;use Closure;use think\Config;use think\Request;use think\Response;class AllowCrossDomain{protected $cookieDomain;// header头配置protected $header = ['Access-Control-Allow-Credentials' => 'true','Access-Control-Max-Age' => 1800,'Access-Control-Allow-Methods' => 'GET, POST, PATCH, PUT, DELETE, OPTIONS','Access-Control-Allow-Headers' => 'Authorization, Content-Type, If-Match, If-Modified-Since, If-None-Match, If-Unmodified-Since, X-CSRF-TOKEN, X-Requested-With,token',];/** * AllowCrossDomain constructor. * @param Config $config */public function __construct(Config $config){$this->cookieDomain = $config->get('cookie.domain', '');}/** * 允许跨域请求 * @access public * @param Request $request * @param Closure $next * @param array $header * @return Response */public function handle($request, Closure $next, ?array $header = []){$header = !empty($header) ? array_merge($this->header, $header) : $this->header;if (!isset($header['Access-Control-Allow-Origin'])) {$origin = $request->header('origin');if ($origin && ('' == $this->cookieDomain || strpos($origin, $this->cookieDomain))) {$header['Access-Control-Allow-Origin'] = $origin;} else {$header['Access-Control-Allow-Origin'] = '*';}}return $next($request)->header($header);}}

原文链接：thinkphp6解决跨域 - 简书