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Code:



 

 /*   http://www.oreilly.com/catalog/sax2/

 * SAX2

 *   By David Brownell

 *   First Edition January 2002

 *   ISBN: 0-596-00237-8

 */





 import java.io.ByteArrayInputStream;

import java.io.IOException;

import java.io.Reader;

import java.io.StringReader;

import java.util.Date;

import java.util.Dictionary;



import org.xml.sax.EntityResolver;

import org.xml.sax.InputSource;

import org.xml.sax.SAXException;



// ASSUMES:  this shares a package with a "Storage" class

// that at least maps keys to data.



/**

 * Entity Resolver, with Chaining

 */

public class MyResolver implements EntityResolver

{

    private EntityResolver next;

    private Dictionary     map;



    // n -- optional resolver to consult on failure

    // m -- mapping public ids to preferred URLs

    public MyResolver (EntityResolver n, Dictionary m)

   { next = n; map = m; }



    public InputSource resolveEntity (String publicId, String systemId)

    throws SAXException, IOException

    {

   // magic URL?

   if ("http://localhost/xml/date".equals (systemId)) {

       InputSource     retval = new InputSource (systemId);

       Reader      date;



       date = new StringReader (new Date().toString ());

       retval.setCharacterStream (date);

       return retval;

   }



   // nonstandard URI scheme?

   if (systemId.startsWith ("blob:")) {

       InputSource     retval = new InputSource (systemId);

       String        key = systemId.substring (5);

       byte          data [] = Storage.keyToBlob (key);



       retval.setByteStream (new ByteArrayInputStream (data));

       return retval;

   }



   // use table to map public id to local URL?

   if (map != null && publicId != null) {

       String url = (String) map.get (publicId);

       if (url != null)

      return new InputSource (url);

   }



   // chain to next resolver?

   if (next != null)

       return next.resolveEntity (publicId, systemId);

   return null;

    }

}