CORS error && 302 Found

场景

单点登录认证：访问A系统，在B系统登录认证
此处代码为A系统

controller

@ResponseBody
    @GetMapping("/idp/loginCheck")
    public void loginCheck(HttpServletRequest request, HttpServletResponse httpResponse) throws IOException {
        // bam 的服务器地址
        String amUrl = "https://www.baidu.com/";
        // 应用注册的唯一标识
        String clientId = "client_test";
        // 应用回调地址
        String redirectURI = request.getRequestURI();
        String requestUrl = amUrl + "?client_id=" + clientId
                + "&redirect_uri=" + redirectURI + "&response_type=code&state=" + state;
        httpResponse.sendRedirect(requestUrl);
    }

前端vue

export function loginCheck() {
  return http.get('/idp/loginCheck')
}

import { loginCheck } from '@/api/idp/idp'
router.beforeEach(async(to, from, next) => {
	loginCheck().then(resp => {
	        if ('ok' === resp.data.msg) {
	          // 跳转首页或者原跳转前页面
	          // this.$router.push({ path: '/' });
	          console.log("11111")
	        } else {
	          console.log("88888888888888888")
	        }
	      })
})

报错

解决方案

前端中访问后台接口的方式修改为：

window.location.href = `/idp/loginCheck`;

疑问

前面也试了nginx添加跨域配置、拦截器添加配置，都不生效，奇怪