Java Tutorial/XML/Entities

Escapes all necessary characters in the String so that it can be used in an XML doc

   <source lang="java">

/**

* $Revision: 10205 $
* $Date: 2008-04-11 15:48:27 -0700 (Fri, 11 Apr 2008) $
*
* Copyright (C) 2004-2008 Jive Software. All rights reserved.
*
* This software is published under the terms of the GNU Public License (GPL),
* a copy of which is included in this distribution, or a commercial license
* agreement with Jive.
*/

import java.io.UnsupportedEncodingException; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import java.text.BreakIterator; import java.util.*; import java.util.concurrent.ConcurrentHashMap; /**

* Utility class to peform common String manipulation algorithms.
*/

public class StringUtils {

   // Constants used by escapeHTMLTags
   private static final char[] QUOTE_ENCODE = """.toCharArray();
   private static final char[] AMP_ENCODE = "&".toCharArray();
   private static final char[] LT_ENCODE = "<".toCharArray();
   private static final char[] GT_ENCODE = ">".toCharArray();
   private StringUtils() {
       // Not instantiable.
   }
   /**
    * Escapes all necessary characters in the String so that it can be used
    * in an XML doc.
    *
    * @param string the string to escape.
    * @return the string with appropriate characters escaped.
    */
   public static String escapeForXML(String string) {
       if (string == null) {
           return null;
       }
       char ch;
       int i = 0;
       int last = 0;
       char[] input = string.toCharArray();
       int len = input.length;
       StringBuilder out = new StringBuilder((int)(len * 1.3));
       for (; i < len; i++) {
           ch = input[i];
           if (ch > ">") {
           }
           else if (ch == "<") {
               if (i > last) {
                   out.append(input, last, i - last);
               }
               last = i + 1;
               out.append(LT_ENCODE);
           }
           else if (ch == "&") {
               if (i > last) {
                   out.append(input, last, i - last);
               }
               last = i + 1;
               out.append(AMP_ENCODE);
           }
           else if (ch == """) {
               if (i > last) {
                   out.append(input, last, i - last);
               }
               last = i + 1;
               out.append(QUOTE_ENCODE);
           }
       }
       if (last == 0) {
           return string;
       }
       if (i > last) {
           out.append(input, last, i - last);
       }
       return out.toString();
   }

}</source>

Preventing Expansion of Entity References While Parsing an XML File

   <source lang="java">

import java.io.File; import javax.xml.parsers.DocumentBuilderFactory; import org.w3c.dom.Document; public class Main {

 public static void main(String[] argv) throws Exception{
   DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
   factory.setValidating(true);
   // Prevent expansion of entity references
   factory.setExpandEntityReferences(false);
   // Create the builder and parse the file
   Document doc = factory.newDocumentBuilder().parse(new File("filename"));
 }

}</source>

Resolving entities found in source XML during parsing

   <source lang="java">

import javax.xml.parsers.SAXParser; import javax.xml.parsers.SAXParserFactory; import org.xml.sax.Attributes; import org.xml.sax.InputSource; import org.xml.sax.SAXException; import org.xml.sax.SAXParseException; import org.xml.sax.helpers.DefaultHandler; public class Main {

 public static void main(String[] argv) throws Exception {
   SAXParserFactory factory = SAXParserFactory.newInstance();
   factory.setValidating(true);
   SAXParser parser = factory.newSAXParser();
   SaxHandler handler = new SaxHandler();
   parser.parse("sample.xml", handler);
 }

} class SaxHandler extends DefaultHandler {

 public InputSource resolveEntity(String publicId, String systemId) {
   if (systemId.equals("http://www.my-company.ru/order-1.0.dtd")) {
     return new InputSource(getClass().getResourceAsStream("order.dtd"));
   } else {
     return null;
   }
 }
 public void startElement(String uri, String localName, String qName, Attributes attrs)
     throws SAXException {
   if (qName.equals("order")) {
   }
 }
 public void error(SAXParseException ex) throws SAXException {
   System.out.println("ERROR: [at " + ex.getLineNumber() + "] " + ex);
 }
 public void fatalError(SAXParseException ex) throws SAXException {
   System.out.println("FATAL_ERROR: [at " + ex.getLineNumber() + "] " + ex);
 }
 public void warning(SAXParseException ex) throws SAXException {
   System.out.println("WARNING: [at " + ex.getLineNumber() + "] " + ex);
 }

}</source>