关于springboot2.4跨域配置问题

 1、如果只是一个简单的springboot demo，用以下配置就行
新建config类

```
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、但是实际开发中我们需要结合，spring-security、oauth2等等，就会发现上面的配置失效了，那是因为前面的Filter优先级太高了，那我们可以采取如下配置

```

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));
        //这里设置优先级最高
        bean.setOrder(Ordered.HIGHEST_PRECEDENCE);
        return bean;
    }
}