从用户控制到 aspx 的事件委派

Created: November-22, 2018

通常，如果我们想要完全封装并且不想公开我们的方法，我们会选择这种方法。

ASCX

<div style="width: 100%;">
  <asp:Button ID="btnAdd" runat="server" 
    Text="Add" OnClick="btnAdd_Click"></asp:button>
  <asp:button id="btnEdit" runat="server" 
    text="Edit" onclick="btnEdit_Click"> </asp:button>
  <asp:button id="btnDelete" runat="server" 
    text="Delete" onclick="btnDelete_Click">    </asp:Button>
  <asp:button id="btnReset" runat="server" 
    text="Reset" onclick="btnReset_Click"></asp:button>
</div>

Ascx.cs

public delegate void ActionClick();

public partial class EventDelegation : System.Web.UI.UserControl
{
    public event ActionClick OnAddClick;
    public event ActionClick OnDeleteClick;
    public event ActionClick OnEditClick;
    public event ActionClick OnResetClick;
    protected void btnAdd_Click(object sender, EventArgs e)
    {
        if(OnAddClick!= null)
        {
            OnAddClick();
        }
    }

    protected void btnEdit_Click(object sender, EventArgs e)
    {
        if (OnEditClick != null)
        {
            OnEditClick();
        }
    }

    protected void btnDelete_Click(object sender, EventArgs e)
    {
        if(OnDeleteClick!= null)
        {
            OnDeleteClick();
        }
    }

    protected void btnReset_Click(object sender, EventArgs e)
    {
        if(OnResetClick!= null)
        {
            OnResetClick();
        }
    }
}

用户控件指定一些公共事件，如 OnAddClick，OnEditClick 等，它们声明一个委托。任何想要使用这些事件的人都需要添加 EventHandler，以便在发生相应的按钮单击事件时执行。

Aspx 设计

<%@ Register src="Controls/EventDelegation.ascx" 
       tagname="EventDelegation" tagprefix="uc1" %>
    
    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
       "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    
    <html xmlns="http://www.w3.org/1999/xhtml" >
    <head runat="server">
        <title></title>
    </head>
    <body>
        <form id="form1" runat="server">
        <div>
            <uc1:Direct ID="Direct1" runat="server" />
        </div>
        </form>
    </body>
    </html>

Aspx.cs

public partial class EventDelegation : System.Web.UI.Page
{
    protected override void OnInit(EventArgs e)
    {
        base.OnInit(e);
        ActionControl.OnAddClick += ActionControl_OnAddClick;
        ActionControl.OnDeleteClick += ActionControl_OnDeleteClick;
        ActionControl.OnEditClick += ActionControl_OnEditClick;
        ActionControl.OnResetClick += ActionControl_OnResetClick;
    }

    private void ActionControl_OnResetClick()
    {
        Response.Write("Reset done.");
    }

    private void ActionControl_OnEditClick()
    {
        Response.Write("Updated.");
    }

    private void ActionControl_OnDeleteClick()
    {
        Response.Write("Deleted.");
    }

    private void ActionControl_OnAddClick()
    {
        Response.Write("Added.");
    }
}