Completely solve SpringBoot cross-domain and Swagger cross-domain problems

CROS cross-domain principle

Cross-domain resource sharing (CORS) is a mechanism that uses additional HTTP headers to tell the browser to allow web applications running on one origin (domain) to be allowed to access specified resources from different origin servers. When a resource requests a resource from a domain or port different from the server where the resource itself is located, the resource initiates a cross-domain HTTP request.

The cross-domain resource sharing (CORS) mechanism allows Web application servers to perform cross-domain access control, so that cross-domain data transmission can be carried out safely. Modern browsers support the use of CORS in API containers (such as XMLHttpRequest or Fetch) to reduce the risk of cross-domain HTTP requests.

Cross-domain configuration file CorsConfig

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.*;

/**
 * @version 1.0
 * @classname CorsConfig
 * @description 解决跨域问题,重写父类提供的跨域请求处理的接口
 * @date 2021/2/24 00:06
 * @created by MelodyJerry
 */
@Configuration
@EnableWebMvc
//public class CorsConfig implements WebMvcConfigurer { //控制台提示No mapping for GET时,替换下行
public class CorsConfig extends WebMvcConfigurationSupport {
    
    

    /*
     * 这里主要为了解决跨域问题,所以重写addCorsMappings方法
     */
    @Override
    //public void addCorsMappings(CorsRegistry registry) { //控制台提示No mapping for GET时,替换下行
    protected void addCorsMappings(CorsRegistry registry) {
    
    
        //设置允许跨域的路径
        registry.addMapping("/**") //所有的当前站点的请求地址，都支持跨域访问
                //设置允许跨域请求的域名,二选一allowedOrigins或allowedOrigins
                //.allowedOrigins("*") //注意access-control-allow-origin时,allowedOrigins不能为*
                //.allowedOrigins("域名") //如果是localhost则很难配置，因为在跨域请求的时候，外部域的解析可能是localhost、127.0.0.1、主机名
                .allowedOriginPatterns("*") // 所有的外部域都可跨域访问
                //放行哪些原始域(请求方式)
                .allowedMethods("GET","HEAD","POST","PUT","DELETE","OPTIONS")
                //设置允许的请求头
                .allowedHeaders("*")
                //暴露哪些头部信息（因为跨域访问默认不能获取全部头部信息）
                .exposedHeaders("access-control-allow-headers",
                        "access-control-allow-methods",
                        "access-control-allow-origin",
                        "access-control-max-age",
                        "X-Frame-Options")
                //是否允许证书(是否支持跨域用户凭证),不再默认开启
                .allowCredentials(true)
                //跨域允许时间
                .maxAge(3600);
    }

    /*
     * 跨域配置后swagger2可能不能访问，需要增加如下配置
     * 原因: 不能访问的原因的swagger的内置接口被拦截器拦下来了，需要将swagger加到拦截器的排除列表中。
     * @param registry
     */
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
    
    
        registry.addResourceHandler("swagger-ui.html")
                .addResourceLocations("classpath:/META-INF/resources/");
        registry.addResourceHandler("doc.html")
                .addResourceLocations("classpath:/META-INF/resources/");
        registry.addResourceHandler("/webjars/**")
                .addResourceLocations("classpath:/META-INF/resources/webjars/");
    }
}

May encounter

(1).allowedMethods("*") problem

It is noteworthy .allowedMethods("*")and Access-Control-Allow-Originconfigure it, this console will report the following error:

Probably meaning: allowCredentialsis truethe time, allowedOriginscan not contain a special value, " *" because it is not in the " Access Control Allow Origin" in response to the head of the set value. To allow credentials to point to a set of sources, please list them explicitly, or consider using " allowedOriginPatterns" instead .

There are two solutions in this case, the second is recommended :

1. .allowedOrigins("域名")
2. Suggest.allowedOriginPatterns("*")

(2)报错o.s.web.servlet.PageNotFound ：No mapping for GET

The above prompt appears on the console o.s.web.servlet.PageNotFound ：No mapping for GET, and the solution is simple:
change extends WebMvcConfigurationSupportto implements WebMvcConfigurer
(the corresponding protected void addCorsMappingschange to public void addCorsMappings)