Erreur Création flux RSS fichier XML - Java

Question

je suis en train de créer un rssfeed en utilisant java c'est la classe i utilise

import com.rssFeed.domain.RSS; 
import com.rssFeed.domain.RSSItem; 
import java.io.FileOutputStream; 
import java.util.Iterator; 
import javax.xml.stream.XMLEventFactory; 
import javax.xml.stream.XMLEventWriter; 
import javax.xml.stream.XMLOutputFactory; 
import javax.xml.stream.XMLStreamException; 
import javax.xml.stream.events.Characters; 
import javax.xml.stream.events.EndElement; 
import javax.xml.stream.events.StartDocument; 
import javax.xml.stream.events.StartElement; 
import javax.xml.stream.events.XMLEvent; 



public class RssBuilder { 

    private static String XML_BLOCK = "\n"; 
    private static String XML_INDENT = "\t"; 

    public static void BuildRss(RSS rss, String xmlfile) throws Exception { 

     XMLOutputFactory output = XMLOutputFactory.newInstance();   
     XMLEventWriter writer = output.createXMLEventWriter(new FileOutputStream(xmlfile)); 
     try 
     {     
     XMLEventFactory eventFactory = XMLEventFactory.newInstance(); 
     XMLEvent endSection = eventFactory.createDTD(XML_BLOCK); 

     StartDocument startDocument = eventFactory.createStartDocument(); 
     writer.add(startDocument); 
     writer.add(endSection); 

     StartElement rssStart = eventFactory.createStartElement("", "", "rss"); 
     writer.add(rssStart); 
     writer.add(eventFactory.createAttribute("version", "2.0")); 
     writer.add(endSection); 

     writer.add(eventFactory.createStartElement("", "", "channel")); 
     writer.add(endSection); 

     createNode(writer, "title", rss.getTitle()); 
     createNode(writer, "description", rss.getDescription()); 
     createNode(writer, "link", rss.getLink()); 
     createNode(writer, "dateCreated", rss.getDateCreated().toString()); 

     createNode(writer, "language", rss.getLanguage()); 
     createNode(writer, "pubDate", rss.getPubDate().toString()); 
     createNode(writer, "dateModified", rss.getDateModified().toString()); 
     createNode(writer, "dateModified", rss.getDateModified().toString()); 
     createNode(writer, "pubDate", rss.getPubDate().toString()); 
     createNode(writer, "lastBuildDate", rss.getLastBuildDate().toString()); 
     createNode(writer, "language", rss.getLanguage().toString()); 
     createNode(writer, "rating", rss.getRating().toString()); 

     Iterator<RSSItem> iterator = rss.getRssItems().iterator(); 
     while (iterator.hasNext()) { 
      RSSItem entry = iterator.next(); 
      writer.add(eventFactory.createStartElement("", "", "item")); 
      writer.add(endSection); 

      createNode(writer, "title", entry.getTitle()); 
      createNode(writer, "description", entry.getDescription()); 
      createNode(writer, "link", entry.getLink()); 
      createNode(writer, "dateCreated", entry.getDateCreated().toString()); 
      createNode(writer, "pubDate", entry.getDateModified().toString()); 
      writer.add(eventFactory.createEndElement("", "", "item")); 
      writer.add(endSection); 
     } 

     writer.add(endSection); 
     writer.add(eventFactory.createEndElement("", "", "channel")); 
     writer.add(endSection); 
     writer.add(eventFactory.createEndElement("", "", "rss")); 

     writer.add(endSection); 
     writer.add(eventFactory.createEndDocument()); 
     writer.close(); 
     } 
     catch(Exception e) 
     { 
      writer.close(); 
     } 
    } 

    private static void createNode(XMLEventWriter eventWriter, String name, String value)throws XMLStreamException { 

     XMLEventFactory eventFactory = XMLEventFactory.newInstance(); 
     XMLEvent endSection = eventFactory.createDTD(XML_BLOCK); 
     XMLEvent tabSection = eventFactory.createDTD(XML_INDENT); 

     StartElement sElement = eventFactory.createStartElement("", "", name); 
     eventWriter.add(tabSection); 
     eventWriter.add(sElement); 

     Characters characters = eventFactory.createCharacters(value); 
     eventWriter.add(characters); 

     EndElement eElement = eventFactory.createEndElement("", "", name); 
     eventWriter.add(eElement); 
     eventWriter.add(endSection); 
    } 

} 

Mais je reçois l'erreur suivante

type Exception report 

message 

descriptionThe server encountered an internal error() that prevented it from fulfilling this request. 

exception 

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is javax.xml.stream.XMLStreamException: Can not write DOCTYPE declaration (DTD) when not in prolog any more (state 2; start element(s) written) 

root cause 

javax.xml.stream.XMLStreamException: Can not write DOCTYPE declaration (DTD) when not in prolog any more (state 2; start element(s) written) 

qu'est-ce qu'il signifier?

Answer 1

Cela signifie que le code tente d'écrire des informations DTD en dehors de l'endroit où les informations DTD sont légales dans les documents XML.

Un DTD (Définition du type de document) décrit la structure autorisée (et éventuellement le contenu) du document. Je pense que les infos DTD doivent apparaître avant le nœud racine du document (dans le prologue). En regardant le code que vous avez fourni, je pense qu'il existe de nombreux endroits où la variable endSection est écrite dans l'écrivain. endSection semble contenir une déclaration DTD. Essayez de supprimer les lignes qui écrivent endSection après le premier.

Answer 2

Ma réponse est l'extension de Brabster

XMLEvent endSection = eventFactory.createDTD(XML_BLOCK); 
StartDocument startDocument = eventFactory.createStartDocument(); 
writer.add(startDocument); 
writer.add(endSection); 

Pour StartDocument, endSection est correcte. Mais

StartElement rssStart = eventFactory.createStartElement("", "", "rss"); 
writer.add(rssStart); 
writer.add(eventFactory.createAttribute("version", "2.0")); 
writer.add(endSection); 
// --> here we will writer like this 
writer.add(eventFactory.createCharacters("\n"));