nginx解决no-referrer-when-downgrade，设置了‘Access-Control-Allow-Origin‘ ‘*‘依旧跨域

location /api {
        add_header 'Access-Control-Allow-Origin' '*' always;
        add_header 'Access-Control-Allow_Credentials' 'true' always;
        add_header 'Access-Control-Allow-Headers' 'Authorization,Accept,Origin,DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Range,Range' always;
        add_header 'Access-Control-Allow-Methods' 'GET,POST,OPTIONS,PUT,DELETE,PATCH' always;

        if ($request_method = 'OPTIONS') {
                add_header 'Access-Control-Max-Age' 1728000;
                add_header 'Content-Type' 'text/plain charset=UTF-8';
                add_header 'Content-Length' 0;
                add_header 'Access-Control-Allow-Origin' '*' always;
                add_header 'Access-Control-Allow_Credentials' 'true' always;
                add_header 'Access-Control-Allow-Headers' 'Authorization,Accept,Origin,DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Range,Range' always;
                add_header 'Access-Control-Allow-Methods' 'GET,POST,OPTIONS,PUT,DELETE,PATCH' always;

                return 204;
        }
        proxy_pass http://127.0.0.1:8081;
}