跨域访问，后台处理

<httpProtocol>
      <customHeaders>
        <add name="Access-Control-Allow-Origin" value="*" />
        <add name="Access-Control-Max-Age" value="30" />
        <add name="Access-Control-Allow-Methods" value="GET,POST,PUT,DELETE,OPTIONS" />
        <add name="Access-Control-Allow-Headers" value="Content-Type, Accept" />
      </customHeaders>
    </httpProtocol>

在<system.webServer> </system.webServer>中插入上面代码段