渲染用户控件并调用他们的 Page_Load

Question

以下代码将不起作用，因为控件（page1、page2、page3）要求调用它们的“Page_Load”事件。

using System;
using System.IO;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using iTextSharp.text;
using iTextSharp.text.html.simpleparser;
using iTextSharp.text.pdf;

public partial class utilities_getPDF : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        // add user controls to the page
        AddContentControl("controls/page1");
        AddContentControl("controls/page2");
        AddContentControl("controls/page3");

        // set up the response to download the rendered PDF...
        Response.ContentType = "application/pdf";
        Response.ContentEncoding = System.Text.Encoding.UTF8;
        Response.AddHeader("Content-Disposition", "attachment;filename=FileName.pdf");
        Response.Cache.SetCacheability(HttpCacheability.NoCache);

        // get the rendered HTML of the page
        System.IO.StringWriter stringWrite = new StringWriter();
        System.Web.UI.HtmlTextWriter htmlWrite = new HtmlTextWriter(stringWrite);
        this.Render(htmlWrite);
        StringReader reader = new StringReader(stringWrite.ToString());

        // write the PDF to the OutputStream...
        Document doc = new Document(PageSize.A4);
        HTMLWorker parser = new HTMLWorker(doc);
        PdfWriter.GetInstance(doc, Response.OutputStream);
        doc.Open();
        parser.Parse(reader);
        doc.Close();

    }
    //  the parts are probably irrelevant to the question...
    private const string contentPage = "~/includes/{0}.ascx";
    private void AddContentControl(string page)
    {
        content.Controls.Add(myLoadControl(page));
    }
    private Control myLoadControl(string page)
    {
        return TemplateControl.LoadControl(string.Format(contentPage, page));
    }
}

所以我的问题是：

如何获取控件 HTML？

Answer 1

首先，为了让您动态添加的控件参与页面生命周期，您需要在页面 PreInit 事件中创建它们。见ASP.NET Page Life Cycle

然后要获得完整的 HTML，确保所有页面事件都已处理，您可以覆盖页面渲染方法，如下所示：

using System; 
using System.IO; 
using System.Web; 
using System.Web.UI; 
using System.Web.UI.WebControls; 
using iTextSharp.text; 
using iTextSharp.text.html.simpleparser; 
using iTextSharp.text.pdf; 

public partial class utilities_getPDF : System.Web.UI.Page 
{ 
    protected void Page_PreInit(object sender, EventArgs e) 
    { 
        // add user controls to the page 
        AddContentControl("controls/page1"); 
        AddContentControl("controls/page2"); 
        AddContentControl("controls/page3"); 

    } 
    //  the parts are probably irrelevant to the question... 
    private const string contentPage = "~/includes/{0}.ascx"; 
    private void AddContentControl(string page) 
    { 
        content.Controls.Add(myLoadControl(page)); 
    } 
    private Control myLoadControl(string page) 
    { 
        return TemplateControl.LoadControl(string.Format(contentPage, page)); 
    } 

    protected override void Render(HtmlTextWriter writer)
    {
        //ignore asp.net writer and use your own.
        //base.Render(writer);    
        // set up the response to download the rendered PDF... 
        Response.ContentType = "application/pdf"; 
        Response.ContentEncoding = System.Text.Encoding.UTF8; 
        Response.AddHeader("Content-Disposition", "attachment;filename=FileName.pdf"); 
        Response.Cache.SetCacheability(HttpCacheability.NoCache); 

        // get the rendered HTML of the page 
        System.IO.StringWriter stringWrite = new StringWriter(); 
        System.Web.UI.HtmlTextWriter htmlWrite = new HtmlTextWriter(stringWrite); 
        base.Render(htmlWrite); 
        htmlWrite.Flush();
        htmlWrite.Close();
        StringReader reader = new StringReader(stringWrite.ToString()); 
        System.IO.MemoryStream stream = new MemoryStream();
        // write the PDF to the OutputStream... 
        Document doc = new Document(PageSize.A4); 
        HTMLWorker parser = new HTMLWorker(doc); 
        PdfWriter.GetInstance(doc, stream); 
        doc.Open(); 
        parser.Parse(reader); 
        doc.Close(); 

        //binary write your pdf file
        Response.Clear();
        Response.BinaryWrite(stream.GetBuffer());
        Response.End();

    }
}