Question

我有以下代码，可以在普通按钮的click事件上添加动态LinkButton。 LinkButtons需要一个EventHandler “LinkButton_Click“。由于事件处理程序需要在Page_Load/Page_Init本身注册时，我首先在Page_Load中添加所有可能的链接（在回发场景中）。（总共有四个链接按钮;根据业务场景，屏幕上只显示两个）

代码工作正常，并且在click事件上调用事件处理程序。

注意：业务场景是 - 如果当前时间的第二部分小于30，则需要显示前两个LinkButtons;如果大于30，则需要显示最后两个LinkButtons。

注意：清除控件并在PopulateLinksBasedOnCriteria()方法

中再次添加

问题

在PopulateLinksBasedOnCriteria()方法中，我新建了链接按钮实例。事件处理程序仍在触发。这是有效的，因为在Page_Load中添加的ID是相同的。是否有任何MSDN参考证实了这种行为？（即，事件处理程序将基于Page_Load/Page_Init时注册的ID。即使清除并再次添加控件，这也将起作用）
创建LinkButtons时有一些重复的代码 - 一个在Page_Load内，另一个在PopulateLinksBasedOnCriteria()内。有没有更好的方法来实现这个业务任务而没有重复的代码？

标记

<form id="form1" runat="server">
<div>
    <asp:Button ID="btnAdd" runat="server" Text="Add" OnClick="btnAdd_Click" />
    <br />
    <asp:PlaceHolder ID="plhDynamicLinks" runat="server"></asp:PlaceHolder>
</div>
</form>

代码背后

    protected void Page_Load(object sender, EventArgs e)
    {

        if (Page.IsPostBack)
        {
            LinkButton lnk1 = new LinkButton();
            lnk1.ID = "D1";
            lnk1.Text = "A";
            //Event handler must be registered in the Page_Load/Page_Init
            lnk1.Click += new EventHandler(LinkButton_Click);
            plhDynamicLinks.Controls.Add(lnk1);

            LinkButton lnk2 = new LinkButton();
            lnk2.ID = "D2";
            lnk2.Text = "B";
            lnk2.Click += new EventHandler(LinkButton_Click);
            plhDynamicLinks.Controls.Add(lnk2);

            LinkButton lnk3 = new LinkButton();
            lnk3.ID = "D3";
            lnk3.Text = "C";
            lnk3.Click += new EventHandler(LinkButton_Click);
            plhDynamicLinks.Controls.Add(lnk3);

            LinkButton lnk4 = new LinkButton();
            lnk4.ID = "D4";
            lnk4.Text = "D";
            lnk4.Click += new EventHandler(LinkButton_Click);
            plhDynamicLinks.Controls.Add(lnk4);

        }
    }

    protected void LinkButton_Click(object sender, EventArgs e)
    {
        PopulateLinksBasedOnCriteria();
        LinkButton clickedControl = (LinkButton)sender;
        Response.Write(DateTime.Now.ToString()+"___"+ clickedControl.ID + " Link Button Clicked" );
    }

    protected void btnAdd_Click(object sender, EventArgs e)
    {
        PopulateLinksBasedOnCriteria();
    }

    private void PopulateLinksBasedOnCriteria()
    {
        plhDynamicLinks.Controls.Clear();

        if (DateTime.Now.Second < 30)
        {
            LinkButton linkButton1 = new LinkButton();
            linkButton1.ID = "D1";
            linkButton1.Text = "1";
            plhDynamicLinks.Controls.Add(linkButton1);

            LinkButton linkButton2 = new LinkButton();
            linkButton2.ID = "D2";
            linkButton2.Text = "2";
            plhDynamicLinks.Controls.Add(linkButton2);
        }
        else
        {
            LinkButton linkButton3 = new LinkButton();
            linkButton3.ID = "D3";
            linkButton3.Text = "3";
            plhDynamicLinks.Controls.Add(linkButton3);

            LinkButton linkButton4 = new LinkButton();
            linkButton4.ID = "D4";
            linkButton4.Text = "4";
            plhDynamicLinks.Controls.Add(linkButton4);
        }
    }

Answer 1

我建议在Page_Load事件On postback, how can I check which control cause postback in Page_Init event中检测导致PostBack的原因然后

 if (Page.IsPostBack && *PostBackControl.Name=="btnAdd"*)
            {
if (DateTime.Now.Second < 30)
        {
                LinkButton lnk1 = new LinkButton();
                lnk1.ID = "D1";
                lnk1.Text = "A";
                //Event handler must be registered in the Page_Load/Page_Init
                lnk1.Click += new EventHandler(LinkButton_Click);
                plhDynamicLinks.Controls.Add(lnk1);

                LinkButton lnk2 = new LinkButton();
                lnk2.ID = "D2";
                lnk2.Text = "B";
                lnk2.Click += new EventHandler(LinkButton_Click);
                plhDynamicLinks.Controls.Add(lnk2);
    } else
        {
                LinkButton lnk3 = new LinkButton();
                lnk3.ID = "D3";
                lnk3.Text = "C";
                lnk3.Click += new EventHandler(LinkButton_Click);
                plhDynamicLinks.Controls.Add(lnk3);

                LinkButton lnk4 = new LinkButton();
                lnk4.ID = "D4";
                lnk4.Text = "D";
                lnk4.Click += new EventHandler(LinkButton_Click);
                plhDynamicLinks.Controls.Add(lnk4);
    }
            }
        }

动态控制的事件处理程序的工作

1 个答案: