wxtyixiao 2019-06-28
跨域是指从一个域名的网页去请求另一个域名的资源。比如从 www.a.com 页面去请求 www.b.com 的资源。
浏览器一般默认会禁止跨域访问。因为不安全,容易出现 CSRF(跨站请求伪造)攻击。
Nginx通过添加 Access-Control-Allow-Origin、Access-Control-Allow-Methods、Access-Control-Allow-Headers 等HTTP头信息的方式控制浏览器缓存。
"Access-Control-Allow-Origin" 设置允许发起跨域请求的网站
"Access-Control-Allow-Methods" 设置允许发起跨域请求请求的HTTP方法
"Access-Control-Allow-Headers" 设置允许跨域请求包含 Content-Type头
Syntax: add_header name value [always]; Default: — Context: http, server, location, if in location
# 配置网站www.a.com server { server_name www.a.com; root /vagrant/a; # 允许 http://www.b.com 使用 GET,POST,DELETE HTTP方法发起跨域请求 add_header Access-Control-Allow-Origin http://www.b.com; add_header Access-Control-Allow-Method GET,POST,DELETE; } # 配置网站www.b.com server { server_name www.b.com; root /vagrant/b; } # 配置网站www.c.com server { server_name www.c.com; root /vagrant/c; }
/vagrant/a/a.txt
、/vagrant/b/index.html
、/vagrant/c/index.html
文件Hello,I'm a!
<!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <title>Ajax跨站访问b</title> </head> <body> <h1>Ajax跨站访问b - </h1> </body> <script src="http://apps.bdimg.com/libs/jquery/2.1.4/jquery.min.js"></script> <script> $(function(){ $.ajax({ url: "http://www.a.com/a.txt", type: "GET", success: function (data) { $('h1').append(data); }, error: function (data) { $('h1').append('请求失败!'); } }); }) </script> </html>
<!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <title>Ajax跨站访问c</title> </head> <body> <h1>Ajax跨站访问c - </h1> </body> <script src="http://apps.bdimg.com/libs/jquery/2.1.4/jquery.min.js"></script> <script> $(function(){ $.ajax({ url: "http://www.a.com/a.txt", type: "GET", success: function (data) { $('h1').append(data); }, error: function (data) { $('h1').append('请求失败!'); } }); }) </script> </html>
windows: C:\Windows\System32\drivers\etc\hosts
linux: /etc/hosts
添加如下内容,并保存(192.168.33.88为笔者虚拟机的IP,需自行替换为自己的IP):
192.168.33.88 www.a.com 192.168.33.88 www.b.com 192.168.33.88 www.c.com
http://www.b.com/index.html
和 http://www.c.com/index.html
Ajax跨站访问b - Hello,I'm a!
Ajax跨站访问c - 请求失败!
打开浏览器的开发者模式Console,还可以发现 http://www.c.com/index.html 的页面出现报错:
Failed to load http://www.a.com/a.txt: The 'Access-Control-Allow-Origin' header has a value 'http://www.b.com' that is not equal to the supplied origin. Origin 'http://www.c.com' is therefore not allowed access.