Dropdownlist无刷新年月日选择

其实用UpdataPanel很简单就可以实现的，这里试试用javascript的方法
 DropDownList1代表年，DropDownList2代表月，DropDownList3代表日。
由于用到的是Dropdownlist服务器控件所以要在Page_Load添假相关代码：

 protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {   
            DropDownList2.Attributes.Add("onchange", "return change()");
            DropDownList1.Attributes.Add("onchange", "return change()");
            for (int i = 1950; i <= 2010; i++)
            {
                DropDownList1.Items.Add(i.ToString());
            }
            for (int i = 1; i <= 12; i++)
            {
                DropDownList2.Items.Add(i.ToString());
            }
        }
    }

主要是javascript代码：

function change()
    {
     var year=document.getElementById("DropDownList1");
     var month=document.getElementById("DropDownList2");
     var yearValue=year.options[year.selectedIndex].text;
     var monthValue=month.options[month.selectedIndex].text;
     var x=document.getElementById("DropDownList3");
     while(x.length>0)
     {      
       x.remove(0);
     }
     BindDays(yearValue,monthValue);
    }
function BindDays(year,month)
{
  switch(month)
  {
     case "1":
     case "3":
     case "5":
     case "7":
     case "8":
     case "10":
     case "12":
           for(var i=1;i<=31;i++)
           {
            var y=document.createElement('option');
             y.text=i.toString();
            var x=document.getElementById("DropDownList3");
              try
                {
                x.add(y,null); // standards compliant
                }
              catch(ex)
                {
                x.add(y); // IE only
                }
            }
       break;
       case "2":
           if(CheckLeap(year)=="true")
           {
              for(var i=1;i<=29;i++)
               {
                var y=document.createElement('option');
                 y.text=i.toString();
                var x=document.getElementById("DropDownList3");
                  try
                    {
                    x.add(y,null); // standards compliant
                    }
                  catch(ex)
                    {
                    x.add(y); // IE only
                    }
                }
           }
      if(CheckLeap(year)=="false")
      {
           for(var i=1;i<=28;i++)
           {
            var y=document.createElement('option');
             y.text=i.toString();
            var x=document.getElementById("DropDownList3");
              try
                {
                x.add(y,null); // standards compliant
                }
              catch(ex)
                {
                x.add(y); // IE only
                }
            }
      }
      break;
    case "4":
    case "6":
    case "9":
    case "11":
          for(var i=1;i<=30;i++)
               {
                var y=document.createElement('option');
                 y.text=i.toString();
                var x=document.getElementById("DropDownList3");
                  try
                    {
                    x.add(y,null); // standards compliant
                    }
                  catch(ex)
                    {
                    x.add(y); // IE only
                    }
                }
  }
}
//判断是否为闰年
function CheckLeap(year)
{
      if ((year % 4 == 0 && year % 100 != 0) || (year % 100 == 0 && year % 400 == 0))
        {
            return "true";
        }
        else
        {
            return "false";
        }
}

前台页面就是三个DropDownList控件：

<div style="text-align: center">
        <asp:DropDownList ID="DropDownList1" runat="server">
        </asp:DropDownList><span>年</span>
        <asp:DropDownList ID="DropDownList2" runat="server" >
        </asp:DropDownList><span>月</span>
        <asp:DropDownList ID="DropDownList3" runat="server">
        </asp:DropDownList><span>日</span>
    </div>