前端：

function test(){
    var k_host = window.location.host;
    var k_port = window.location.port;
    var k_protocol = window.location.protocol;
    var k_url = k_protocol+"//"+k_host+ "/user/login";
    $.ajax({
        type:"POST",
        url:k_url,
        data:"abc",
        datatype: "json",//"xml", "html", "script", "json", "jsonp", "text".
 
success:function(data){
            console.log(data);
            console.log(data.code)
        }
    });
}

package com.example.demo.debug.config;

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;
import org.springframework.web.socket.server.standard.ServerEndpointExporter;

@Configuration
public class WebSocketConfig {
    private CorsConfiguration buildConfig() {
        CorsConfiguration corsConfiguration = new 
 
CorsConfiguration();
        corsConfiguration.addAllowedOrigin("*"); // 1
corsConfiguration.addAllowedHeader("*"); // 2
corsConfiguration.addAllowedMethod("*"); // 3
return corsConfiguration;
    }

    @Bean
public CorsFilter corsFilter() {
        UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
        source.registerCorsConfiguration("/**", buildConfig()); // 4
return new CorsFilter(source);
    }

    @Bean
public ServerEndpointExporter serverEndpointExporter() {
        return new ServerEndpointExporter();
    }
}