springboot webapi 支持跨域 CORS

@Configuration
public class corsConfig {
    @Autowired
    varModel varModel_;
    @Bean
    public WebMvcConfigurer corsConfigurer() {
        return new WebMvcConfigurer() {
            @Override
            //重写父类提供的跨域请求处理的接口
            public void addCorsMappings(CorsRegistry registry) {
                //添加映射路径
                registry.addMapping("/**")
                        .allowedHeaders("*")
                        .allowedMethods("*")
                        .allowedOrigins(varModel_.getCorsStrList());
            }
        };
    }
}//end

$.ajax({
            type: "POST",
            url: "http://localhost:8000/a/b",
            contentType: "application/json; charset=utf-8", 
            dataType: "json",
            data: JSON.stringify({
                "requestId": ""
            }),
            success: function (d) {
                console.log(d);
            },
            error: function () {
                //alert("系统错误");
            }
        });