问题
I am making a web application that takes RSS feeds from websites(URLs are in database) and then loads them into my web application. But I am getting this error
System.Xml.XmlException: Root element is missing. root element is missing. at line : rssdoc.load(rssStream);
Exception Details: System.Xml.XmlException: There are multiple root elements. Line 2, position 2. so how to encapsulate everything else by single xml element
Here is my code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Xml;
using System.Net;
using System.Text;
using System.IO;
using System.Data;
using System.Data.SqlClient;
public partial class poletics : System.Web.UI.Page
{
public SqlConnection oldbcon = new SqlConnection();
static int n = 0;
static DataTable dt = new DataTable();
protected void Page_Load(object sender, EventArgs e)
{
oldbcon = opncon();
using (oldbcon)
{
SqlDataAdapter ad = new SqlDataAdapter("SELECT * from LebPolRss", oldbcon);
ad.Fill(dt);
}
int f = 3;
while (n < f)
{
for (int i = 0; i < dt.Rows.Count; i++)
{
Literal feed = new Literal();
try
{
feed.Text = ProcessRss(dt.Rows[i][3].ToString(), dt.Rows[i][4].ToString());
}
catch (WebException ex)
{
WebResponse response = ex.Response;
}
Panel1.Controls.Add(feed);
}
n++;
}
}
public static string ProcessRss(string rssUrl, string feed)
{
WebRequest request = WebRequest.Create(rssUrl);
WebResponse response = request.GetResponse();
StringBuilder sb = new StringBuilder("");
Stream rssStream = response.GetResponseStream();
XmlDocument rssDoc = new XmlDocument();
rssDoc.Load(rssStream);//here is the line where the exception thrown
XmlNodeList rssItems = rssDoc.SelectNodes("rss/channel/item");
string title = "";
string link = "";
string description = "";
int upperlimit = rssItems.Count;
if (upperlimit > n)
upperlimit = n + 1;
if (upperlimit > 0)
{
sb.Append("<ul>");
for (int i = 0; i < upperlimit - n; i++)
{
XmlNode rssDetail;
rssDetail = rssItems.Item(i + n).SelectSingleNode("title");
if (rssDetail != null)
{
if (feed.ToString().Equals("tayyar"))
{
title = rssDetail.InnerText.Substring(5);
}
else
{
if (rssDetail.InnerText.Length > 75)
{
title = rssDetail.InnerText.Substring(0, 75);
}
else
{
title = rssDetail.InnerText;
}
}
}
else
{
title = "";
}
rssDetail = rssItems.Item(i + n).SelectSingleNode("link");
if (rssDetail != null)
{
if (feed.ToString().Equals("tayyar"))
{
if (rssDetail.InnerText.Substring(0, 21).CompareTo("http://www.tayyar.org") != 0)
{
link = "http://www.tayyar.org" + rssDetail.InnerText;
}
else
{
link = rssDetail.InnerText;
}
}
else
{
link = rssDetail.InnerText;
}
}
else
{
link = "";
}
rssDetail = rssItems.Item(i + n).SelectSingleNode("description");
if (rssDetail != null)
{
if (!rssDetail.InnerText.Substring(3, 3).Equals("Ad:"))
{
description = rssDetail.InnerText;
}
}
else
{
description = "";
}
switch (feed)
{
case "tayyar": sb.Append("<div class='imgsep'><li><img src='logos/tayyar.jpg' width='50px' height='30px'/> <a href='" + link + "' target='_blank'>" + title + "</a> <img src='Images/smallarrow.png'/></li></div>");
break;
case "14march": sb.Append("<div class='imgsep'><li><img src='logos/14march.jpg' width='50px' height='30px'/> <a href='" + link + "' target='_blank'>" + title + "</a> <img src='Images/smallarrow.png'/></li></div>");
break;
case "annahar": sb.Append("<div class='imgsep'><li><img src='logos/annahar.jpg' width='50px' height='30px'/> <a href='" + link + "' target='_blank'>" + title + "</a> <img src='Images/smallarrow.png'/></li></div>");
break;
case "alakhbar": sb.Append("<div class='imgsep'><li><img src='logos/akhbar.jpg' width='50px' height='30px'/> <a href='" + link + "' target='_blank'>" + title + "</a> <img src='Images/smallarrow.png'/></li></div>");
break;
case "sadabeirut": sb.Append("<div class='imgsep'><li><img src='logos/echobeirut.png' width='50px' height='30px'/> <a href='" + link + "' target='_blank'>" + title + "</a> <img src='Images/smallarrow.png'/></li></div>");
break;
case "assafir": sb.Append("<div class='imgsep'><li><img src='logos/assafir.png' width='50px' height='30px'/> <a href='" + link + "' target='_blank'>" + title + "</a> <img src='Images/smallarrow.png'/></li></div>");
break;
case "aliwaa": sb.Append("<div class='imgsep'><li><img src='logos/aliwaa.jpg' width='50px' height='30px'/> <a href='" + link + "' target='_blank'>" + title + "</a> <img src='Images/smallarrow.png'/></li></div>");
break;
}
}
sb.Append("</ul>");
}
return sb.ToString();
}
protected void LinkButton1_Click(object sender, EventArgs e)
{
oldbcon = opncon();
using (oldbcon)
{
SqlDataAdapter ad = new SqlDataAdapter("SELECT * from LebPolRss", oldbcon);
ad.Fill(dt);
}
n = 4;
for (int i = 0; i < dt.Rows.Count; i++)
{
Literal feed = new Literal();
try
{
feed.Text = ProcessRss(dt.Rows[i][3].ToString(), dt.Rows[i][4].ToString());
}
catch (WebException ex) { WebResponse response = ex.Response; }
Panel1.Controls.Add(feed);
}
LinkButton1.Visible = false;
}
public static SqlConnection opncon()
{
string connectionString = "Data Source=RAYYAN-THINK;Initial Catalog=newsProject;Integrated Security=True";
SqlConnection conn = new SqlConnection(connectionString);
return conn;
}
}
Stack Trace:
[XmlException: Root element is missing.]
System.Xml.XmlTextReaderImpl.Throw(Exception e) +69
System.Xml.XmlTextReaderImpl.ParseDocumentContent() +5589128
System.Xml.XmlTextReaderImpl.Read() +215
System.Xml.XmlLoader.Load(XmlDocument doc, XmlReader reader, Boolean preserveWhitespace) +145
System.Xml.XmlDocument.Load(XmlReader reader) +107
System.Xml.XmlDocument.Load(Stream inStream) +130
poletics.ProcessRss(String rssUrl, String feed) in c:\Users\RAYYAN\Documents\Visual Studio 2012\WebSites\WebSite1\poletics.aspx.cs:57
poletics.Page_Load(Object sender, EventArgs e) in c:\Users\RAYYAN\Documents\Visual Studio 2012\WebSites\WebSite1\poletics.aspx.cs:36
System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +51
System.Web.UI.Control.OnLoad(EventArgs e) +92
System.Web.UI.Control.LoadRecursive() +54
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +772
回答1:
Error explains the most common case of the exception : you have a root element missing in your xml.
Meaning, you most likely have several 'root' elements therefore those are not root elements. You need a single xml element encapsulating everything else. This is first thing to check
来源：https://stackoverflow.com/questions/19706778/system-xml-xmlexception-root-element-is-missing