登录时动态替换undefined动态，但是一直没有变化

Question

<script>
    $(function () {
        $.get("findUserServlet",{},function (data) {
            //{uid:1,name:'李四'}
            var msg = "欢迎回来，"+data.name;
            $("#span_username").html(msg);

        });
    });

</script>

@WebServlet("/findUserServlet")
public class FindUserServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //从session中获取登录用户
        Object user = request.getSession().getAttribute("user");
        //将user写回客户端

        ObjectMapper mapper = new ObjectMapper();
        response.setContentType("application/json;charset=utf-8");
        mapper.writeValue(response.getOutputStream(),user);


    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    }
}

Answer 1

后台打印 user 对象，前台再 console.log data 看看数据是否一致。
F12 打开浏览器的开发者模式可以看到控制台的内容，还有 network 的网络请求响应。