如何通过单击UserControl中的按钮将UserControl中存在的文本框值传递给Aspx页面标签

您将需要有一个自定义事件，并且还需要像这样在UserControl中公开的Text属性TextBox。

public partial class YourUserControl : UserControl
{
    public String Text
    {
        get
        {
            return this.txtBox1.Text;
        }
        //write the setter property if you would like to set the text 
        //of the TextBox from your aspx page
        //set
        //{
        //    this.txtBox1.Text = value;
        //}
    }

    public delegate void TextAppliedEventHandler(Object sender, EventArgs e);
    public event TextAppliedEventHandler TextApplied;

    protected virtual void OnTextApplied(EventArgs e)
    {
        //Taking a local copy of the event, 
        //as events can be subscribed/unsubscribed asynchronously.
        //If that happens after the below null check then 
        //NullReferenceException will be thrown
        TextAppliedEventHandler handler = TextApplied;

        //Checking if the event has been subscribed or not...
        if (handler != null)
            handler(this, e);
    }

    protected void yourUserControlButton_Click(Object sender, EventArgs e)
    {
        OnTextApplied(EventArgs.Empty);
    }
}

然后，在您放置的aspx页面中YourUserControl（或您正在从后面的代码中动态添加它），您可以像这样订阅此事件。

protected void Page_Load(Object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        yourUserControl.TextApplied += new YourUserControl.TextAppliedEventHandler(yourUserControl_TextApplied)
    }
}

您可以像这样在页面中使用用户控件的自定义事件。

protected void yourUserControl_TextApplied(Object sender, EventArgs e)
{
    yourLabelInYourPage.Text = yourUserControl.Text;
}

你完成了...

编辑：您可以根据需要重命名控件和事件。我仅将名称用于示例目的。

编辑：在网站项目中，如果要动态添加用户控件，则可能需要ASP像这样在页面中包含名称空间。

using ASP;

并将其添加Directive到页面的aspx标记中。

<%@ Reference Control="~/PathToYourUserControl/YourUserControl.ascx" %>