AJAX

使用AJAX接收后端发出的数据

2017-12-05 20-17-48 的屏幕截图.png

前端页面写的内容

//使用ajax输出从后台获取的信息
<script type="text/javascript">
    $(document).ready(function () {
        $.post("/UserServlet?method=username",
            function (data) {
                console.log(data[0].u_userid)

                //获取input框id,通过id输出内容

                // $("#username1").val(data[0].u_userid);
                // $("#username2").val(data[0].u_username);

                //通过获取input框的name,输出内容

                $("input[name='u_userid']").val(data[0]['u_userid']);
                $("input[name='u_username']").val(data[0]['u_username']);
                $("input[name='u_password']").val(data[0]['u_password']);
                $("input[name='u_sex']").val(data[0]['u_sex']);
                // $("input[name='u_class']").val(data[0]['u_class']);
            },"json"
        );
    });
</script>

• input框的内容

账号:<input type="text" name="u_userid" id="username1" val="" />
姓名:<input type="text" name="u_username" id="username2" val="" />
...

servlet代码

2017-12-05 20-39-12 的屏幕截图.png

protected void username(HttpServletRequest request,
                 HttpServletResponse response) throws ServletException, IOException {
        /*UserBean userBean = new UserBean();*/
        List list = (List) request.getSession().getAttribute("info");
        UserBean userBean = (UserBean) list.get(0);
        int u_id = userBean.getU_id();

        UserBean userBean1 = userService.username(u_id);
        System.out.println(userBean1);
        JSONArray jsonArray = JSONArray.fromObject(userBean1);
        response.getWriter().print(jsonArray);
    }

• service
  UserService userService = new UserServiceImpl();
  UserBean username(int u_id);
• serviceImpl
  UserDao userDao =new UserDaoImpl();
  @Override
  public UserBean username(int u_id) {
  return userDao.username(u_id);
  }
• dao
  UserBean username(int u_id);

• daoImpl

  
  2017-12-05 20-47-02 的屏幕截图.png

   public UserBean username(int u_id){
       //在数据库中查询信息
       try{
           UserBean userBean = new UserBean();
           Connection conn = ConnUtil.getConnextion();
           String changeSql = "select * from user WHERE u_id = ?";
           PreparedStatement pstm = conn.prepareStatement(changeSql);
           pstm.setInt(1, u_id);
           ResultSet rs = pstm.executeQuery();
           if(rs.next()) {
              userBean.setU_userid(rs.getString(2));
              userBean.setU_username(rs.getString(3));
              userBean.setU_password(rs.getString(4));
              userBean.setU_sex(rs.getString(5));
              userBean.setU_img(rs.getString(6));
               return userBean;
           }
       }catch (Exception e){
           System.out.println(e);
       }
       return null;
   }

使用session接收后端发出的数据

登录成功后数据库的信息就就已经存在了session中,只需要在前端显示页面,即引入js接收即可:
如下所示:

    <%
        List list = (List) request.getSession().getAttribute("info");
        UserBean userBean = (UserBean) list.get(0);
    %>
.
.
.
用户名:<input type="text" value="<%=userBean.getU_userid()%>"