在本地开发时，小程序项目端口与.net项目端口不一致，小程序访问.net接口报错。
报错信息：Access to XMLHttpRequest at ‘https://localhost:44385/Product/GetProductList’ from origin ‘http://localhost:8080’ has been blocked by CORS policy: Response to preflight request doesn’t pass access control check: No ‘Access-Control-Allow-Origin’ header is present on the requested resource.
解决方法：在.net项目的web.config文件中system.webServer标签内添加如下内容。
