.aspx界面

<script language="javascript" type="text/javascript">function getAbsolutePosition(element){var point = { x: element.offsetLeft, y: element.offsetTop }; if (element.offsetParent){var parentPoint = this.getAbsolutePosition(element.offsetParent);point.x += parentPoint.x;point.y += parentPoint.y;}return point;};function myclick(){     var myTextbox=document.getElementById("myRegisterTime");var point1 = getAbsolutePosition(myTextbox);document.getElementById("caDiv").style.display="block";document.getElementById("caDiv").style.left=point1.x;document.getElementById("caDiv").style.top=point1.y;} function divonclick(){document.getElementById("caDiv").style.display="none";}</script>

添加TextBox与Calendar控件

 <asp:TextBox ID="myRegisterTime" runat="server" OnDataBinding="BindDate"></asp:TextBox><div id="caDiv" style="display:none;position: absolute;" οnclick="divonclick()"><asp:Calendar ID="Calendar1" runat="server" BackColor="White" BorderColor="#3366CC" Font-Names="Verdana" Font-Size="8pt" ForeColor="#003399" Height="200px" Width="220px" onselectionchanged="Calendar1_SelectionChanged" BorderWidth="1px" CellPadding="1" DayNameFormat="Shortest"><SelectedDayStyle BackColor="#009999" ForeColor="#CCFF99" Font-Bold="True" /><SelectorStyle BackColor="#99CCCC" ForeColor="#336666" /><WeekendDayStyle BackColor="#CCCCFF" /><TodayDayStyle BackColor="#CCCCCC" /><OtherMonthDayStyle ForeColor="#999999" /><NextPrevStyle Font-Size="8pt" ForeColor="#CCCCFF" /><DayHeaderStyle BackColor="#99CCCC" ForeColor="#336666" Height="1px" /><TitleStyle BackColor="#003399"   Font-Bold="True" Font-Size="10pt" ForeColor="#CCCCFF" BorderColor="#3366CC" BorderWidth="1px" Height="25px" /></asp:Calendar>
</div>

.cs界面

 protected void Page_Load(object sender, EventArgs e){if (!IsPostBack){myRegisterTime.Attributes.Add("onfocus", "javascript:myclick()");}}//日历事件protected void Calendar1_SelectionChanged(object sender, EventArgs e){if (Calendar1.SelectedDate > DateTime.Now.AddDays(-1.0))myRegisterTime.Text = Calendar1.SelectedDate.ToLongDateString();else{//WebHelper.Alert("日期无效，请重选！");Calendar1.SelectedDate = DateTime.Now;}}

效果图展示：


TextBox控件中只能显示当前及以后的日期，对于已经过去的日期则不能选择

参考自：
https://blog.csdn.net/u012709815/article/details/22340207?ops_request_misc=%257B%2522request%255Fid%2522%253A%2522160239626619195264715445%2522%252C%2522scm%2522%253A%252220140713.130102334.pc%255Fall.%2522%257D&request_id=160239626619195264715445&biz_id=0&utm_medium=distribute.pc_search_result.none-task-blog-2_allfirst_rank_v2~rank_v25-1-22340207.pc_search_result_cache&utm_term=ASP.NET怎样实现TextBox控件与Calendar控&spm=1018.2118.3001.4187