add_header允许跨域
1.跨域是浏览器的问题
明确一点跨域是浏览器问题，浏览器出现跨域问题的时候，会发送两次请求，第一次请求的方法是‘Option’，第二次请求是正常的Get或者post。
2.跨域解决方法
利用nginx解决跨域，新建一个server，server中内容如下，其中proxy_pass是代理的ip地址以及端口。也就是我们最终请求的地址。也就是在第一次请求的时候，由nginx直接返回204状态，不经过最终的ip地址。（注意修改proxy_pass中的地址）
server {
listen 8099;
server_name localhost;
#charset koi8-r;
#access_log logs/host.access.log main;
location / {
root html;
index index.html index.htm;
# 配置html以文件方式打开
# 配置html以文件方式打开
if ($request_method = 'POST') {
add_header 'Access-Control-Allow-Origin' '*' always;
add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS,PUT,DELETE,OPTION';
add_header 'Access-Control-Allow-Credentials' 'true';
add_header 'Access-Control-Allow-Headers' 'DNT,X-Mx-ReqToken,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Authorization,Accept,Referer,Accept-Encoding,Accept-Language,Access-Control-Request-Headers,Access-Control-Request-Method,Connection,Host,Origin,Sec-Fetch-Mode';
}
if ($request_method = 'GET') {
add_header 'Access-Control-Allow-Origin' '*' always;
add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS,PUT,DELETE,OPTION';
add_header 'Access-Control-Allow-Credentials' 'true';
add_header 'Access-Control-Allow-Headers' 'DNT,X-Mx-ReqToken,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Authorization,Accept,Referer,Accept-Encoding,Accept-Language,Access-Control-Request-Headers,Access-Control-Request-Method,Connection,Host,Origin,Sec-Fetch-Mode';
}
if ($request_method = 'OPTIONS') {
add_header 'Access-Control-Allow-Origin' '*' always;
add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS,PUT,DELETE,OPTION';
add_header 'Access-Control-Allow-Credentials' 'true';
add_header 'Access-Control-Allow-Headers' 'DNT,X-Mx-ReqToken,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Authorization,Accept,Referer,Accept-Encoding,Accept-Language,Access-Control-Request-Headers,Access-Control-Request-Method,Connection,Host,Origin,Sec-Fetch-Mode';
return 204;
}
# 代理到ip地址端口
proxy_pass http://xxxx:xxx;
}
#error_page 404 /404.html;
# redirect server error pages to the static page /50x.html
#
error_page 500 502 503 504 /50x.html;
location = /50x.html {
root html;
}
# proxy the PHP scripts to Apache listening on 127.0.0.1:80
#
#location ~ \.php$ {
# proxy_pass http://127.0.0.1;
#}
# pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
#
#location ~ \.php$ {
# root html;
# fastcgi_pass 127.0.0.1:9000;
# fastcgi_index index.php;
# fastcgi_param SCRIPT_FILENAME /scripts$fastcgi_script_name;
# include fastcgi_params;
#}
# deny access to .htaccess files, if Apache's document root
# concurs with nginx's one
#
#location ~ /\.ht {
# deny all;
#}
}
3.问题汇总
(1)出现如下问题。
The ‘Access-control-allow-origin’ header contains multiple values ‘‘,but only one is allow’
是出现了两次的问题，修改上述server中内容。注释get和post中access-control-allow-origin。访问成功。（注意修改proxy_pass）
https://blog.csdn.net/weixin_41415235/article/details/122940569
