router.beforeEach((to,from,next)=>{
  if(to.path=='/login' || localStorage.getItem('token')){
   next();
  }else{
   alert('请重新登录');
   next('/login');
  }
})

axios.interceptors.request.use(function (config) {
 let token = window.localStorage.getItem("token");
   if (token) {
     config.headers.token = token;  //将token放到请求头发送给服务器
   }
   return config; // 最终需要返回config
  }, function (error) {
    return Promise.reject(error);
});