Nginx反向代理405跨域问题CORS解决方案

在api接口开发和调用的过程中，nginx反向代理后，可能会出现405跨域问题。导致接口无法访问。
有两种处理方案，一种是卸载nginx，使用apache作为web服务器。
一种是修改nginx的配置，使其OPTIONS预请求转发为204。相关代码如下：

#
# Wide-open CORS config for nginx
#
location / {
     if ($request_method = 'OPTIONS') {
        add_header 'Access-Control-Allow-Origin' '*';
        add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
        #
        # Custom headers and headers various browsers *should* be OK with but aren't
        #
        add_header 'Access-Control-Allow-Headers' 'Origin, X-Requested-With, Content-Type, Accept, Authorization';
        #
        # Tell client that this pre-flight info is valid for 20 days
        #
        add_header 'Access-Control-Max-Age' 1728000;
        add_header 'Content-Type' 'text/plain; charset=utf-8';
        add_header 'Content-Length' 0;
        return 200;
      }
      if ($request_method = 'POST') {
        add_header 'Access-Control-Allow-Origin' '*';
        add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
        add_header 'Access-Control-Allow-Headers' 'Origin, X-Requested-With, Content-Type, Accept, Authorization';
        add_header 'Access-Control-Expose-Headers' 'Content-Length,Content-Range';
      }
      if ($request_method = 'GET') {
        add_header 'Access-Control-Allow-Origin' '*';
        add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
        add_header 'Access-Control-Allow-Headers' 'Origin, X-Requested-With, Content-Type, Accept, Authorization';
        add_header 'Access-Control-Expose-Headers' 'Content-Length,Content-Range';
      }
}

反向代理除了跨域问题，还存在缓存问题要处理。同样也是通过修改nginx配置来解决。