Render User Controls and call their Page_Load

问题

The following code will not work because the controls (page1, page2, page3) require that their "Page_Load" event gets called.

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));
    }
}

So my question is:

How can I get the controls HTML?

回答1:

First of all, for your dynamically added controls to participate in the page life cycle you need to create them in page PreInit event. see ASP.NET Page Life Cycle

Then to get complete HTML, making sure all page events were processed you override page Render method as follows:

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();

    }
} 

来源：https://stackoverflow.com/questions/2791292/render-user-controls-and-call-their-page-load