以编程方式生成的控件出现问题

本文关键字：问题 控件 编程 方式生 | 更新日期: 2023-09-27 18:00:19

public partial class Default2 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        GenerateButtons generate = new GenerateButtons();
        generate.Generate5Controls(PlaceHolder1);
    }

}

class GenerateButtons
{
    PlaceHolder placeHolder;
   public  void Generate5Controls(PlaceHolder placeH)
    {
        placeHolder = placeH;
        for (int i = 0; i < 5; i++)
        {
            Button newBtn = new Button();
            newBtn.Click += btn_Click;
            newBtn.Text = "PageLoadButton Created. Number: "+i;
            placeHolder.Controls.Add(newBtn);
        }
    }
    public void btn_Click(object sender, EventArgs e)
    {
        Button newBTN = new Button();
        newBTN.Text = "A New Button was added by the button event btn_click";
        newBTN.Click += btn2_Click;
        placeHolder.Controls.Add(newBTN);
    }
    public void btn2_Click(object sender, EventArgs e)
    {
        Button newBTN = new Button();
        newBTN.Text = "A New Button was added by the button event btn2_click";
        placeHolder.Controls.Add(newBTN);
    }
}

我想要btn_click&btn2_click可以将所有帖子都回击。。当我点击程序创建的按钮时，它在每次回发后都会消失，并且它的事件不会触发(btn2_click(。我知道我可以在回发时生成按钮。。但我不想那样做！！我想知道如何更新占位符的状态。。。使得唯一的按钮将出现，并且在Generate5Controls(PlaceHolder placeH(中生成的5个按钮将消失。

我可以使用boolViewstate来阻止这种生成。生成5控件(PlaceHolder1(；正在执行。。

但问题是，我如何使程序生成的按钮出现！？

以编程方式生成的控件出现问题

您应该在每个PostBack上生成控件，或者您可以生成一次控件，保存在会话中，并添加从session on page_load事件中生成的控件。

protected void Page_Load(object sender, EventArgs e)
    {
       if(Session["GeneratedButtons"] == null)
       {
          GenerateButtons generate = new GenerateButtons();
          generate.Generate5Controls(PlaceHolder1);
       }
       else
       {
           List<Control> generatedControls = Session["GeneratedButtons"] as List<Control>;
           foreach(Control oneControl in generatedControls)
           {
               PlaceHolder1.Controls.Add(oneControl);
           }
       }
    }
class GenerateButtons
{
    PlaceHolder placeHolder;
   public  void Generate5Controls(PlaceHolder placeH)
    {
        placeHolder = placeH;
        List<Control> generatedControls = new List<Control>();
        for (int i = 0; i < 5; i++)
        {
            Button newBtn = new Button();
            newBtn.Click += btn_Click;
            newBtn.Text = "PageLoadButton Created. Number: "+i;
            placeHolder.Controls.Add(newBtn);
            AddControlToSession(newBtn);
        }
    }
    public void btn_Click(object sender, EventArgs e)
    {
        Button newBTN = new Button();
        newBTN.Text = "A New Button was added by the button event btn_click";
        newBTN.Click += btn2_Click;
        placeHolder.Controls.Add(newBTN);
        AddControlToSession(newBtn);
    }
    public void btn2_Click(object sender, EventArgs e)
    {
        Button newBTN = new Button();
        newBTN.Text = "A New Button was added by the button event btn2_click";
        placeHolder.Controls.Add(newBTN);
        AddControlToSession(newBtn);
    }
    private void AddControlToSession(Control ctrl)
    {
        List<Control> generatedControls = Session["GeneratedButtons"] as List<Control>;
        if(generatedControls == null)
        {
            generatedControls = new List<Control>();
        }
        generatedControls.Add(ctrl);
        Session["GeneratedButtons"] = generatedControls;
    }
}
相关文章：