动态增加的DropDownList如何保持状态，下面就是解决方法。
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<![CDATA[<%@ Page Language="C#" EnableViewstate="true"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>院系选择</title>
<script language="C#" runat=server>
public void Page_load(object Sender, EventArgs e)
{
xike.Attributes.Add("onchange",
"document.all." + HiddenValue.ClientID + ".value = xike.options[xike.selectedIndex].value;");
if(!Page.IsPostBack)
{
xike.Items.Add("01-1系");
xike.Items.Add("01-2系");
xike.Items.Add("01-3系");
xike.Items.Add("01-4系");
xike.Items.Add("01-5系");
}
}
public void SelChange(object Sender, EventArgs e)
{
switch(xueyuan.SelectedItem.Value)
{
case "01" :
xike.Items.Clear();
xike.Items.Add("01-1系");
xike.Items.Add("01-2系");
xike.Items.Add("01-3系");
xike.Items.Add("01-4系");
xike.Items.Add("01-5系");
break;
case "02" :
xike.Items.Clear();
xike.Items.Add("02-1系");
xike.Items.Add("02-2系");
xike.Items.Add("02-3系");
xike.Items.Add("02-4系");
break;
case "03" :
xike.Items.Clear();
xike.Items.Add("03-1系");
xike.Items.Add("03-2系");
xike.Items.Add("03-3系");
break;
case "04" :
xike.Items.Clear();
xike.Items.Add("04-1系");
xike.Items.Add("04-2系");
break;
case "05" :
xike.Items.Clear();
xike.Items.Add("05-1系");
xike.Items.Add("05-2系");
xike.Items.Add("05-3系");
xike.Items.Add("05-4系");
xike.Items.Add("05-5系");
break;
case "06" :
xike.Items.Clear();
xike.Items.Add("数学系");
xike.Items.Add("计算数学系");
xike.Items.Add("计算机科学系");
xike.Items.Add("信息工程系");
xike.Items.Add("金融数学系");
xike.Items.Add("计算中心");
xike.Items.Add("大学数学教研部");
break;
}
}
public void SelResult(object Sender, EventArgs e)
{
label1.Text="你选择了:" + xueyuan.SelectedItem.Text +" : "+ HiddenValue.Value ;
for (int i=0; i<xike.Items.Count; i++) {
if (xike.Items[i].Value == HiddenValue.Value)
xike.Items[i].Selected = true;
}
}
</script>
</head>
<body>
<Form runat="server">
学院:
<<a href="http://www.chinaitpower.com/Dev/Web/Asp/index.html" target="_blank">asp</a>:DropDownList ID="xueyuan" runat="server" AutoPostBack="True"
OnSelectedIndexChanged="SelChange" >
<<a href="http://www.chinaitpower.com/Dev/Web/Asp/index.html" target="_blank">asp</a>:ListItem value="01" selected>1 文学院</<a href="http://www.chinaitpower.com/Dev/Web/Asp/index.html" target="_blank">asp</a>:ListItem>
<<a href="http://www.chinaitpower.com/Dev/Web/Asp/index.html" target="_blank">asp</a>:ListItem value="02">2 社发院</<a href="http://www.chinaitpower.com/Dev/Web/Asp/index.html" target="_blank">asp</a>:ListItem>
<<a href="http://www.chinaitpower.com/Dev/Web/Asp/index.html" target="_blank">asp</a>:ListItem value="03">3 管理院</<a href="http://www.chinaitpower.com/Dev/Web/Asp/index.html" target="_blank">asp</a>:ListItem>
<<a href="http://www.chinaitpower.com/Dev/Web/Asp/index.html" target="_blank">asp</a>:ListItem value="04">4 教科院</<a href="http://www.chinaitpower.com/Dev/Web/Asp/index.html" target="_blank">asp</a>:ListItem>
<<a href="http://www.chinaitpower.com/Dev/Web/Asp/index.html" target="_blank">asp</a>:ListItem value="05">5 外文院</<a href="http://www.chinaitpower.com/Dev/Web/Asp/index.html" target="_blank">asp</a>:ListItem>
<<a href="http://www.chinaitpower.com/Dev/Web/Asp/index.html" target="_blank">asp</a>:ListItem value="06">6 数科院</<a href="http://www.chinaitpower.com/Dev/Web/Asp/index.html" target="_blank">asp</a>:ListItem>
</<a href="http://www.chinaitpower.com/Dev/Web/Asp/index.html" target="_blank">asp</a>:DropDownList>
系科:
<<a href="http://www.chinaitpower.com/Dev/Web/Asp/index.html" target="_blank">asp</a>:DropDownList id="xike" runat="server" AutoPostBack="true"
OnSelectedIndexChanged="SelResult"/>
<<a href="http://www.chinaitpower.com/Dev/Web/Asp/index.html" target="_blank">asp</a>:Label id="label1" runat="server" />
<input id="HiddenValue" type=hidden value="" runat=server>
</form>
</body>
</html>
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