springboot四种跨域方式，后台解决跨域问题

方式一

实现 WebMvcConfigurer#addCorsMappings 的方法

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.CorsRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class CorsConfig implements WebMvcConfigurer {

    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/**")
                .allowedOrigins("*")
                .allowedMethods("GET", "HEAD", "POST", "PUT", "DELETE", "OPTIONS")
                .allowCredentials(true)
                .maxAge(3600)
                .allowedHeaders("*");
    }
}

方式二

重新注入 CorsFilter，自定义CorsFilter类

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.cors.CorsConfiguration;
import org.springframework.web.cors.UrlBasedCorsConfigurationSource;
import org.springframework.web.filter.CorsFilter;

/**
 * 解决跨域
 */
@Configuration
public class CorsFilterConfig {


    /**
     * 开启跨域访问拦截器
     *
     * @date 2021/4/29 9:50
     */
    @Bean
    public CorsFilter corsFilter() {
        //创建CorsConfiguration对象后添加配置
        CorsConfiguration corsConfiguration = new CorsConfiguration();
        //设置放行哪些原始域
        corsConfiguration.addAllowedOrigin("*");
        //放行哪些原始请求头部信息
        corsConfiguration.addAllowedHeader("*");
        //放行哪些请求方式
        corsConfiguration.addAllowedMethod("*");

        UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
        //2. 添加映射路径
        source.registerCorsConfiguration("/**", corsConfiguration);
        return new CorsFilter(source);
    }
}

方式三

创建过滤器 filter 解决跨域

@Slf4j
@Component
@WebFilter(urlPatterns = { "/*" }, filterName = "headerFilter")
public class HeaderFilter implements Filter {
    @Override
    public void doFilter(ServletRequest request, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
        HttpServletResponse response = (HttpServletResponse) resp;
        //解决跨域访问报错
        response.setHeader("Access-Control-Allow-Origin", "*");
        response.setHeader("Access-Control-Allow-Methods", "POST, PUT, GET, OPTIONS, DELETE");
        //设置过期时间
        response.setHeader("Access-Control-Max-Age", "3600");
        response.setHeader("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept, client_id, uuid, Authorization");
        // 支持HTTP 1.1.
        response.setHeader("Cache-Control", "no-cache, no-store, must-revalidate");
        // 支持HTTP 1.0. response.setHeader("Expires", "0");
        response.setHeader("Pragma", "no-cache");
        // 编码
        response.setCharacterEncoding("UTF-8");
        chain.doFilter(request, resp);
    }

    @Override
    public void init(FilterConfig filterConfig) {
        log.info("跨域过滤器启动");
    }

    @Override
    public void destroy() {
        log.info("跨域过滤器销毁");
    }
}

方式四

在需要跨域的方法上加注解 @CrossOrigin

注意：Spring Framework 4.2 GA为CORS提供了第一类支持，使您比通常的基于过滤器的解决方案更容易和更强大地配置它。所以springMVC的版本要在4.2或以上版本才支持@CrossOrigin

@RestController
@CrossOrigin
@RequestMapping("/upload")
public class FileController {
}