xmlreaderadapter.java

webwork source

/**
 * WebWork, Web Application Framework
 *
 * Distributable under Apache license.
 * See terms of license at opensource.org
 */
package webwork.view.xslt.SAXAdapter;

import org.apache.commons.logging.*;
import org.xml.sax.*;
import org.xml.sax.helpers.DefaultHandler;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;


/**
 * XMLReaderAdapter converts a java bean to its xml representation. It does
 * this by simulating a SAX XMLReader which an xslt processor can use as
 * a SAXSource.
 *
 * The actual work is done in XMLWalker as the interface XMLReader is stateful
 * in respect to the input source. So this class is actually a facade to the
 * stateless class @see XMLWalker
 *
 * @author <a href="mailto:[e-mail]">Philipp Meier</a>
 */
public class XMLReaderAdapter implements Locator, XMLReader
{

   private String systemId;
   private Object object;
   private String root = null;
   private ContentHandler contentHandler = new DefaultHandler();
   private XMLWalker walker;

   public XMLReaderAdapter(XMLWalker walker, Object object)
   {
      this(walker, object, "data");
   }

   public XMLReaderAdapter(XMLWalker walker, Object object, String root)
   {
      this.walker = walker;
      this.object = object;
      this.root = root;
   }

   public void parse() throws IOException, SAXException
   {
      if (object == null)
      {
         throw new SAXException("no object to parse defined " + "(use XMLReaderAdapter.setObject)");
      }
      if (contentHandler == null)
      {
         throw new SAXException("no content handler defined " + "(use XMLReaderAdapter.setContentHandler");
      }
      contentHandler.setDocumentLocator(this);
      contentHandler.startDocument();
      /** Keeps track of walked instances to detect circular references. **/
      List walkedInstances = new ArrayList();
      walker.walk(contentHandler, object, root, walkedInstances);
      contentHandler.endDocument();
   }

   /**
    * SAX Reader/Locator Dummy Implementation
    */
   public String getPublicId()
   {
      return null;
   }

   public String getSystemId()
   {
      return systemId;
   }

   public int getLineNumber()
   {
      return -1;
   }

   public int getColumnNumber()
   {
      return -1;
   }

   public void setEntityResolver(EntityResolver resolver)
   {
   }

   public EntityResolver getEntityResolver()
   {
      return null;
   }

   public void setDTDHandler(DTDHandler handler)
   {
   }

   public DTDHandler getDTDHandler()
   {
      return null;
   }

   public void setContentHandler(ContentHandler handler)
   {
      this.contentHandler = handler;
   }

   public ContentHandler getContentHandler()
   {
      return contentHandler;
   }

   public void setErrorHandler(ErrorHandler handler)
   {
   }

   public ErrorHandler getErrorHandler()
   {
      return null;
   }

   public void parse(InputSource source) throws IOException, SAXException
   {
      parse();
   }

   public void parse(String s) throws IOException, SAXException
   {
      parse();
   }

   public void setObject(Object object)
   {
      this.object = object;
   }

   public void setRoot(String root)
   {
      this.root = root;
   }

   public boolean getFeature(String featureId) throws SAXNotRecognizedException
   {
      return false;
   }

   public void setFeature(String featureId, boolean on) throws SAXNotRecognizedException, SAXNotSupportedException
   {
   }

   public Object getProperty(String name) throws SAXNotRecognizedException
   {
      throw new SAXNotRecognizedException(name);
   }

   public void setProperty(String propertyId, Object property) throws SAXNotRecognizedException, SAXNotSupportedException
   {
   }

}