委托(delegate)实现自定义控件的AutoPostBack功能

项目中用到ajax：

<asp:ScriptManager ID="ScriptManager1" runat="server">
    </asp:ScriptManager>

<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Always">
                                <ContentTemplate>
                                    <asp:HiddenField runat="server" ID="HiddenField_CarNo"></asp:HiddenField>
                                </ContentTemplate>
                                <Triggers>
                                    <asp:AsyncPostBackTrigger ControlID="Identification" />
                                    <asp:AsyncPostBackTrigger ControlID="ddlID" />
                                    <asp:AsyncPostBackTrigger ControlID="ddlLicense" />
                                </Triggers>
                            </asp:UpdatePanel>

其中有自定义控件ddlID包括DropDownList和TextBox。遂利用delegate设置自定义控件的autopostback功能。

控件页面代码如下：

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<asp:DropDownList id="cbb_License" runat="server" Width="80px" AppendDataBoundItems="true" OnSelectedIndexChanged="LicenseTextChanged">
<asp:ListItem Text="请选择" Value="00000000-0000-0000-0000-000000000000">
</asp:ListItem>
</asp:DropDownList>
<asp:TextBox id="txt_License" runat="server" Width="48px" MaxLength="5" OnTextChanged="LicenseTextChanged"></asp:TextBox>

两个用户控件都加了事件LicenseTextChanged。

控件后台代码如下：

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public delegate void LicensePlateChangedEnventHandler(object sender, EventArgs args);

       public event LicensePlateChangedEnventHandler LicensePlateChanged;//委托定义

       protected void LicenseTextChanged(object sender, EventArgs e) {

           RaiseEvent(sender, e);
       }//时间定义

       private void RaiseEvent(object sender, EventArgs e) {
           if (LicensePlateChanged != null) {
               LicensePlateChanged(sender, e);
           }
       }//关联委托