跨域配置

SpringBoot跨域配置

我们的后端使用Spring Boot。Spring Boot跨域非常简单，只需书写以下代码即可。

@Configuration
public class CustomCORSConfiguration {
  private CorsConfiguration buildConfig() {
    CorsConfiguration corsConfiguration = new CorsConfiguration();
    corsConfiguration.addAllowedOrigin("*");
    corsConfiguration.addAllowedHeader("*");
    corsConfiguration.addAllowedMethod("*");
    return corsConfiguration;
  }
  @Bean
  public CorsFilter corsFilter() {
    UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
    source.registerCorsConfiguration("/**", buildConfig());
    return new CorsFilter(source);
  }
}

Nginx跨域配置

某天，我们将Spring Boot应用用Nginx反向代理。而前端跨域请求的需求不减，于是乎。

Nginx跨域也比较简单，只需添加以下配置即可。

location / {
    proxy_pass http://localhost:8080;
    if ($request_method = 'OPTIONS') {
        add_header 'Access-Control-Allow-Origin' '*';
        add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
        add_header 'Access-Control-Allow-Headers' 'DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Range,Range,Token';
        add_header 'Access-Control-Max-Age' 1728000;
        add_header 'Content-Type' 'text/plain; charset=utf-8';
        add_header 'Content-Length' 0;
        return 204;
    }
    if ($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,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Range,Range,Token';
        add_header 'Access-Control-Expose-Headers' 'DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Range,Range,Token';
    }
    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,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Range,Range,Token';
        add_header 'Access-Control-Expose-Headers' 'DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Range,Range,Token';
    }
}

其中： add_header 'Access-Control-Expose-Headers' 务必加上你请求时所带的header。例如本例中的“Token”，其实是前端传给后端过来的。如果记不得也没有关系，浏览器的调试器会有详细说明。

参考文档：https://enable-cors.org/server_nginx.html

B.T.W，阿里云中文档描述到Nginx也可通过crossdomain.xml配置文件跨域：https://helpcdn.aliyun.com/knowledge_detail/41123.html ，不过笔者并未采用这种方式。

CORS on Nginx

The following Nginx configuration enables CORS, with support for preflight requests.

#
# Wide-open CORS config for nginx
#
location / {
     if ($request_method = 'OPTIONS') {
        add_header 'Access-Control-Allow-Origin' '*';
        add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
        #
        # Custom headers and headers various browsers *should* be OK with but aren't
        #
        add_header 'Access-Control-Allow-Headers' 'DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Range,Range';
        #
        # Tell client that this pre-flight info is valid for 20 days
        #
        add_header 'Access-Control-Max-Age' 1728000;
        add_header 'Content-Type' 'text/plain; charset=utf-8';
        add_header 'Content-Length' 0;
        return 204;
     }
     if ($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,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Range,Range';
        add_header 'Access-Control-Expose-Headers' 'DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Range,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,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Range,Range';
        add_header 'Access-Control-Expose-Headers' 'DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Range,Range';
     }
}

浏览器设置跨域

Chrome、Firefox本身是可以通过配置支持跨域请求的。

• Chrome跨域：参考文档：http://www.cnblogs.com/laden666666/p/5544572.html
  
• Firefox跨域：参考文档：https://segmentfault.com/q/1010000002532581/a-1020000002533699