Asp.net 下拉列表SelectedIndexChanged事件处理程序在ListView控件内多次激发

我使用

DataTable

绑定了一个列表视图控件。在

ItemDataBound

中，我正在创建

DropDownList

并以编程方式添加项，并将

SelectedIndexChanged

事件绑定到该下拉列表

在我的例子中，假设在ListView中创建了三行，并且在列表视图中有三个下拉列表。当我将下拉选择更改为第一个

DropDownList

时，然后

SelectedIndexChanged

触发一次。然后我在第二个

DropDownList

中更改选择，然后

SelectedIndexChanged

触发两次，然后在第二个

DropDownList

中更改选择，然后

SelectedIndexChanged

触发三次

protected void dlMain_ItemDataBound(object sender, System.Web.UI.WebControls.DataListItemEventArgs e)
{
    if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
    {
        DataRowView currentRow = (DataRowView)e.Item.DataItem;
        Panel pnl = (Panel)e.Item.FindControl("pnlUser");
        if (pnl != null)
        {
            pnl.Controls.Add(new LiteralControl(currentRow.Row.ItemArray[1].ToString()));
        }
        Panel pnlDropDown = (Panel)e.Item.FindControl("pnlDropDown");
        if (pnlDropDown != null)
        {
            if (dtCustomers.Rows.Count > 0)
            {
                DataRow[] customers = dtCustomers.Select("KItemId = " + Convert.ToInt32(currentRow.Row.ItemArray[0]) + "");
                if (customers.Length > 0)
                {
                    DropDownList customerDDL = new DropDownList();
                    ListItem baseItem = new ListItem("-- Select --", "0");
                    customerDDL.Items.Add(baseItem);
                    foreach (DataRow customerRow in customers)
                    {
                        ListItem newItem = new ListItem(customerRow["CustName"].ToString(), customerRow["CustId"].ToString());
                        customerDDL.Items.Add(newItem);
                    }
                    customerDDL.ID = "Customers" + Convert.ToString(currentRow.Row.ItemArray[0]);
                    customerDDL.AutoPostBack = true;
                    customerDDL.SelectedIndexChanged += customerDDL_SelectedIndexChanged;
                    pnlDropDown.Controls.Add(customerDDL);
                }
            }
        }
    }
}  

为了检查事件的行为，我在

SelectedIndexChanged

事件中编写了一行代码

void customerDDL_SelectedIndexChanged(object sender, EventArgs e)
{

    DropDownList changedList = (DropDownList)sender;

}

在这里，当我第一次更改DropDown1的选定值时，我得到的是

ID

DropDown1，然后我更改了DropDown2的选定值，事件触发两次，第一次我得到的是发送方对象DrowDown1的ID，然后控件再次出现在事件中，我得到了发送方对象DropDown2

---

我应该怎么做才能在

SelectedIndexChanged

中获得精确控件的选定项？

您需要这样做

protected void Page_Load(object sender, EventArgs e)
        {

            if (!Page.IsPostBack)
            {

                int[] arr = { 1, 3, 5 };
                ListView1.DataSource = arr;
                ListView1.DataBind();
            }
        }

        protected void ddl_SelectedIndexChanged(object sender, EventArgs e)
        {
            ddlval.Text = ((DropDownList)sender).SelectedValue;
        }
        protected void ListView1_ItemDataBound(object sender, ListViewItemEventArgs e)
        {

            if (e.Item.ItemType == ListViewItemType.DataItem  )
                {


                    DropDownList ddl = e.Item.FindControl("ddl") as DropDownList;
                    ddl.SelectedIndexChanged += new EventHandler(ddl_SelectedIndexChanged);

                }

        }

ASPX页

<asp:listview id="ListView1" runat="server" onitemdatabound="ListView1_ItemDataBound" xmlns:asp="#unknown">  
         <LayoutTemplate>
            <table cellpadding="2" width="680px" border="0">
                <tr id="Tr1" style="background-color: #ADD8E6" runat="server">                   
                    <th id="Th3" runat="server">
                        E-mail Address
                    </th>
                </tr>
                <tr runat="server" id="itemPlaceholder" />
            </table>

        </LayoutTemplate>     
         <itemtemplate>
            <tr id="Tr2" style="background-color: #CAEEFF" runat="server">

                <td>
                   <asp:dropdownlist id="ddl" runat="server" autopostback="true" onselectedindexchanged="ddl_SelectedIndexChanged">
                <asp:listitem text="Select 1" value="One" selected="True">Review</asp:listitem>
                <asp:listitem text="Select 2" value="Two">Send Back to Level1</asp:listitem>
            </asp:dropdownlist>
                </td>
            </tr>
        </itemtemplate>

</asp:listview>
<asp:label id="ddlval" text="test" runat="server"></asp:label>

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我已经修改了我的代码…并且它在我的本地工作…

感谢您的回答，我尝试了您建议的方法，但得到了相同的结果。i、 e.当我更改第二个下拉列表中的部分时，事件将触发两次：-（您好，先生，如果我放置

Page.IsPostBack

条件，则控件的呈现在第一次加载页面时消失。删除Page.IsPostBack是的，先生，删除条件后，输出相同，

SelectedIndexChanged

多次触发。是否可以防止多次触发处理程序？