问题描述

当出现403跨域错误的时候 No ‘Access-Control-Allow-Origin’ header is present on the requested resource，需要给Nginx服务器配置响应的header参数：

解决方案

location / {
          add_header 'Access-Control-Allow-Origin' "$http_origin";
          add_header 'Access-Control-Allow-Methods' 'GET, POST, PUT, DELETE, OPTIONS';
          add_header 'Access-Control-Allow-Headers' 'DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type    ';
          add_header 'Access-Control-Allow-Credentials' 'true';
          if ($request_method = 'OPTIONS') {
            add_header 'Access-Control-Allow-Origin' "$http_origin";
            add_header 'Access-Control-Allow-Methods' 'GET, POST, PUT, DELETE, OPTIONS';
            add_header 'Access-Control-Allow-Headers' 'DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type    ';
            add_header 'Access-Control-Allow-Credentials' 'true';
            add_header 'Access-Control-Max-Age' 1728000; # 20 天
            add_header 'Content-Type' 'text/html charset=UTF-8';
            add_header 'Content-Length' 0;
            return 200;
        }
}

上述名词解释

Access-Control-Allow-Origin

服务器默认是不被允许跨域的。

给Nginx服务器配置​​Access-Control-Allow-Origin *​​后，表示服务器可以接受所有的请求源（Origin）,即接受所有跨域的请求。

Access-Control-Allow-Headers

Access-Control-Allow-Headers 是为了防止出现以下错误：Request header field Content-Type is not allowed by Access-Control-Allow-Headers in preflight response.

这个错误表示当前请求Content-Type的值不被支持。其实是我们发起了"application/json"的类型请求导致的。这里涉及到一个概念：预检请求（preflight request）,请看下面"预检请求"的介绍。

Access-Control-Allow-Methods

Access-Control-Allow-Methods 是为了防止出现以下错误：

Content-Type is not allowed by Access-Control-Allow-Headers in preflight response.