您可以使用以下方法（如果您不喜欢使用 javascript 构建更复杂的 UI）。
它的工作原理是在页面加载时动态创建属性 DropDownLists（您将根据数据库查询的结果实现它）并隐藏每个属性，以便稍后显示。
在选择了一个类别后，正确的 DropDownLists 就会变得可见（这里的查询再次可以确定哪个属性 DropDownLists 变得可见）。
显然，它可能需要一些修改才能生成一个包含每个 DropDownList 和一个标签控件的面板，而不是仅仅创建一些 DropDownLists。
然后您将显示/隐藏面板而不是 DropDownList，但希望它为您指明正确的方向。
希望这会有所帮助。
标记
<style type="text/css">
select
{
display:block;
margin-top:10px;
}
</style>
....
<asp:ScriptManager ID="scriptManager" runat="server"></asp:ScriptManager>
<asp:UpdatePanel ID="updatePanel" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<!-- Category selection -->
<asp:DropDownList ID="categoryDropDownList" runat="server" AutoPostBack="true" OnSelectedIndexChanged="categoryDropDownList_SelectedIndexChanged">
<asp:ListItem Text="Please select a category" Value="0"></asp:ListItem>
</asp:DropDownList>
<br />
<!-- Used to store the drop downs -->
<asp:Panel ID="dropDownContainer" runat="server"></asp:Panel>
</ContentTemplate>
</asp:UpdatePanel>
代码
protected void Page_Load(object sender, EventArgs e)
{
LoadDropDownLists();
}
private void LoadDropDownLists()
{
//Dummy data, you would pull your categories/attributes from whichever datasource
//you are using
var categories = new[]{
new { Name = "Category 1", Id = 1, Attributes = new string[]{"GA", "FA", "RA"} },
new { Name = "Category 2", Id = 2, Attributes = new string[]{"GA", "NA"} }
};
//Loop through the categories, load the dropdown
foreach (var category in categories)
{
if (!IsPostBack)
categoryDropDownList.Items.Add(new ListItem(category.Name, category.Id.ToString()));
//For each attribute create a drop down and populate with data as required
foreach (var attribute in category.Attributes)
{
string dropDownListId = FormatDropDownListId(attribute);
if (!DropDownListExists(dropDownListId))
{
DropDownList dropDownList = new DropDownList();
dropDownList.ID = dropDownListId;
dropDownList.Visible = false;
dropDownList.Items.Add(new ListItem(attribute));
dropDownContainer.Controls.Add(dropDownList);
}
}
}
}
private bool DropDownListExists(string id)
{
DropDownList dropDownList = (DropDownList)dropDownContainer.FindControl(id);
return dropDownList != null;
}
protected void categoryDropDownList_SelectedIndexChanged(object sender, EventArgs e)
{
//Reset all visible dropdowns
HideAllDropDownLists();
//Get the selected category
string selectedItem = categoryDropDownList.SelectedItem.Value;
switch (selectedItem)
{
case "1":
{
//Here you would connect to db and pull correct attributes
//then set the visible dropdowns as required
SetDropDownVisibility(FormatDropDownListId("GA"));
SetDropDownVisibility(FormatDropDownListId("FA"));
SetDropDownVisibility(FormatDropDownListId("RA"));
} break;
case "2":
{
SetDropDownVisibility(FormatDropDownListId("GA"));
SetDropDownVisibility(FormatDropDownListId("NA"));
} break;
}
}
private void SetDropDownVisibility(string id)
{
DropDownList dropDownList = (DropDownList)dropDownContainer.FindControl(id);
if(dropDownList != null)
dropDownList.Visible = true;
}
private void HideAllDropDownLists()
{
foreach (Control control in dropDownContainer.Controls)
{
control.Visible = false;
}
}
private string FormatDropDownListId(string id)
{
return string.Format("dropDown{0}", id);
}