@Configuration
public class CorsConfiguration {
 @Bean
 public WebMvcConfigurer corsConfigurer() {
  return new WebMvcConfigurerAdapter() {
   @Override
   public void addCorsMappings(CorsRegistry registry) {
    registry.addMapping("/**")
      .allowedHeaders("*")
      .allowedMethods("*")
      .allowedOrigins("*");
   }
  };
 }
}

public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
 //用户已经登录
 if (request.getSession().getAttribute("user") != null) {
  return true;
 }
 //从单点登录返回之后的状态，本系统还不处于登录状态
 //根据code值去获取access_token，然后再根据access_token去获取用户信息，并将用户信息存到session中
 String state = request.getParameter("state");
 String uri = getUri(request);
 if (isLoginFromSSO(state)) {
  String code = request.getParameter("code");
  Object cacheUrl = request.getSession().getAttribute(state);
  if (cacheUrl == null) {
   response.sendRedirect(uri);
   return false;
  }
  HttpUtil client = new HttpUtil();
  StringBuffer sb = new StringBuffer();
  sb.append("code=").append(code)
    .append("&grant_type=").append("authorization_code")
    .append("&client_id=").append(SSOAuth.ClientID)
    .append("&client_secret=").append(SSOAuth.ClientSecret)
    .append("&redirect_uri=").append(URLEncoder.encode((String) cacheUrl));
  String resp = client.post(SSOAuth.AccessTokenUrl, sb.toString());
  Map<String, String> map = new Gson().fromJson(resp, Map.class);
  //根据access_token去获取用户信息
  String accessToken = map.get("access_token");
  HttpUtil http = new HttpUtil();
  http.addHeader("Authorization", "Bearer " + accessToken);
  String encrypt = http.get(SSOAuth.UserUrl);
  String userinfo = decryptUserInfo(encrypt);
  //封装成user对象
  User user = new Gson().fromJson(userinfo, User.class);
  request.getSession().setAttribute("user", user);
  return true;
 }
 //跳转到单点登录界面
 state = Const._SSO_LOGIN + Const.UNDERLINE + RandomUtil.getUUID();
 request.getSession().setAttribute(state, uri);
 String redirectUrl = buildAuthCodeUrl(uri, state);
 response.sendRedirect(redirectUrl);
 return false;
}

window.location.href=this.$api.config.baseUrl+"/system/user/login"

axios.defaults.withCredentials=true;

@Bean
public WebMvcConfigurer corsConfigurer() {
 return new WebMvcConfigurerAdapter() {
  @Override
  public void addCorsMappings(CorsRegistry registry) {
   registry.addMapping("/**")
     .allowedHeaders("*")
     .allowedMethods("*")
     .allowedOrigins("*").allowCredentials(true);
  }
 };
}

//option预检查，直接通过请求
if ("OPTIONS".equals(request.getMethod())){
 return true;
}