On cross domain configuration of springboot2.4

1. If it is just a simple springboot demo, just use the following configuration
Create a new config class

```
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.CorsRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
 
/**
 * @author yk
 * @date 2021/7/19 14:36
 */
@Configuration
public class WebConfig implements WebMvcConfigurer {
    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/**")
                .allowedOriginPatterns("*")
                .allowedMethods("*")
                .maxAge(3600)
                .allowCredentials(true);
    }
}

```

2. However, in actual development, we need to combine spring-security, oauth2, etc., and we will find that the above configuration is invalid, because the priority of the previous Filter is too high, so we can adopt the following configuration

```

import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.Ordered;
import org.springframework.web.cors.CorsConfiguration;
import org.springframework.web.cors.UrlBasedCorsConfigurationSource;
import org.springframework.web.filter.CorsFilter;
 
/**
 * @author yk
 * @date 2021/7/19 16:21
 */
@Configuration
public class CrosConfig {
 
    @Bean
    public FilterRegistrationBean corsFilter() {
        CorsConfiguration config = new CorsConfiguration();
        config.setAllowCredentials(true);
        config.addAllowedOriginPattern("*");
        config.addAllowedHeader("*");
        config.addAllowedMethod("*");
        UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
        source.registerCorsConfiguration("/**", config);
        FilterRegistrationBean bean = new FilterRegistrationBean(new CorsFilter(source));
        // Setting the highest priority here 
        bean.setOrder(Ordered.HIGHEST_PRECEDENCE);
        return bean;
    }
}