C:\tools\nginx-1.28.0\conf\nginx.conf文件，报错：Access to fetch at 'http://localhost/api-aa2-agent12/classes/courses' from origin 'http://localhost:3001' 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.
修改说明
为什么需要处理 OPTIONS 请求？
当浏览器发起跨域请求时，会先发送一个 OPTIONS 预检请求（preflight request）来检查服务器是否允许实际请求。如果 Nginx 不正确处理这个 OPTIONS 请求，浏览器就会报 CORS 错误。
主要改进：
- 单独处理 OPTIONS 请求，直接返回 204 状态码
- 所有 CORS 头添加
always参数，确保在所有响应中都包含 - 增加了
Authorization头的支持，允许传递 token
重新加载 Nginx 后，CORS 错误应该就解决了！
server { listen 80; server_name localhost; location /api-aa2-agent12/ { # 处理 OPTIONS 预检请求 if ($request_method = 'OPTIONS') { add_header 'Access-Control-Allow-Origin' '*' always; add_header 'Access-Control-Allow-Methods' 'GET, POST, PUT, DELETE, PATCH, OPTIONS' always; add_header 'Access-Control-Allow-Headers' 'Authorization, Content-Type, Accept, Origin, User-Agent, DNT, Cache-Control, X-Mx-ReqToken, X-Requested-With' always; add_header 'Access-Control-Max-Age' 1728000 always; add_header 'Content-Type' 'text/plain; charset=utf-8' always; add_header 'Content-Length' 0 always; return 204; } # 设置允许跨域的域，* 表示允许任何域，也可以设置特定的域 add_header 'Access-Control-Allow-Origin' '*' always; # 允许的方法 add_header 'Access-Control-Allow-Methods' 'GET, POST, PUT, DELETE, PATCH, OPTIONS' always; # 允许的头信息字段 add_header 'Access-Control-Allow-Headers' 'Authorization, Content-Type, Accept, Origin, User-Agent, DNT, Cache-Control, X-Mx-ReqToken, X-Requested-With' always; # 缓存时间 add_header 'Access-Control-Max-Age' 1728000 always; proxy_set_header X-Real-IP $remote_addr; proxy_set_header REMOTE-HOST $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_set_header X-NginX-Proxy true; proxy_set_header Connection ''; proxy_http_version 1.1; chunked_transfer_encoding off; proxy_buffering off; proxy_cache off; proxy_pass http://192.168.31.141:1234/; } }
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