在我们的开发中，经常遇到跨域，这个时候，可以通过cors来解决。

解决的方法可以在服务端的代码层或者在web服务器进行设置

在web服务器上进行设置cors 跨域，这样就不必改动代码。以nginx为例子

提示：有时候我们的后端是PHP文件，则需要把跨域的代码加 location ~ \.php(.*)$ 中。

location / {
     if ($request_method = ‘OPTIONS‘) {
        add_header ‘Access-Control-Allow-Origin‘ ‘*‘;
        add_header ‘Access-Control-Allow-Methods‘ ‘GET, POST, OPTIONS‘;
        #
        # Custom headers and headers various browsers *should* be OK with but aren‘t
        #
        add_header ‘Access-Control-Allow-Headers‘ ‘DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range‘;
        #
        # Tell client that this pre-flight info is valid for 20 days
        #
        add_header ‘Access-Control-Max-Age‘ 1728000;
        add_header ‘Content-Type‘ ‘text/plain; charset=utf-8‘;
        add_header ‘Content-Length‘ 0;
        return 204;
     }
     if ($request_method = ‘POST‘) {
        add_header ‘Access-Control-Allow-Origin‘ ‘*‘;
        add_header ‘Access-Control-Allow-Methods‘ ‘GET, POST, OPTIONS‘;
        add_header ‘Access-Control-Allow-Headers‘ ‘DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range‘;
        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‘ ‘DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range‘;
        add_header ‘Access-Control-Expose-Headers‘ ‘Content-Length,Content-Range‘;
     }
}

另外一种可以设置反向代理

location ^~ /api/v1 {
    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;
    }
    # 这下面是要被代理的后端服务器，它们就不需要修改代码来支持跨域了
    proxy_pass http://127.0.0.1:8085;
    proxy_set_header Host $host;
    proxy_redirect off;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_connect_timeout 60;
    proxy_read_timeout 60;
    proxy_send_timeout 60;
 
}

本文分享来自于 :https://cloud.tencent.com/developer/article/1494367