git.gag.com Git - debian/openrocket/blob - core/src/net/sf/openrocket/file/simplesax/SimpleSAX.java

   1 package net.sf.openrocket.file.simplesax;
   2
   3 import java.io.IOException;
   4 import java.util.concurrent.BlockingQueue;
   5 import java.util.concurrent.LinkedBlockingQueue;
   6
   7 import net.sf.openrocket.aerodynamics.WarningSet;
   8
   9 import org.xml.sax.InputSource;
  10 import org.xml.sax.SAXException;
  11 import org.xml.sax.XMLReader;
  12 import org.xml.sax.helpers.XMLReaderFactory;
  13
  14
  15 /**
  16  * A "simple SAX" XML reader.  This system imposes the limit that an XML element may
  17  * contain either textual (non-whitespace) content OR additional elements, but not
  18  * both.  This holds true for both the OpenRocket and RockSim design formats and the
  19  * RockSim engine definition format.
  20  * <p>
  21  * The actual handling is performed by subclasses of {@link ElementHandler}.  The
  22  * initial handler is provided to the {@link #readXML(InputSource, ElementHandler, WarningSet)}
  23  * method.
  24  *
  25  * @author Sampo Niskanen <sampo.niskanen@iki.fi>
  26  */
  27 public class SimpleSAX {
  28
  29         static final XMLReaderCache cache = new XMLReaderCache(10);
  30
  31         /**
  32          * Read a simple XML file.
  33          *
  34          * @param source                        the SAX input source.
  35          * @param initialHandler        the initial content handler.
  36          * @param warnings                      a warning set to store warning (cannot be <code>null</code>).
  37          * @throws IOException          if an I/O exception occurs while reading.
  38          * @throws SAXException         if e.g. malformed XML is encountered.
  39          */
  40         public static void readXML(InputSource source, ElementHandler initialHandler,
  41                         WarningSet warnings) throws IOException, SAXException {
  42
  43                 DelegatorHandler xmlhandler = new DelegatorHandler(initialHandler, warnings);
  44
  45                 XMLReader reader = cache.createXMLReader();
  46                 reader.setContentHandler(xmlhandler);
  47                 reader.setErrorHandler(xmlhandler);
  48                 reader.parse(source);
  49                 cache.releaseXMLReader(reader);
  50         }
  51
  52         private static class XMLReaderCache {
  53
  54                 private final BlockingQueue<XMLReader> queue;
  55                 private XMLReaderCache( int maxSize ) {
  56                         this.queue = new LinkedBlockingQueue<XMLReader>(maxSize);
  57                 }
  58
  59                 private XMLReader createXMLReader() throws SAXException {
  60
  61                         XMLReader reader = queue.poll();
  62                         if ( reader == null ) {
  63                                 reader = XMLReaderFactory.createXMLReader();
  64                         }
  65                         return reader;
  66                 }
  67
  68                 private void releaseXMLReader( XMLReader reader ) {
  69                         queue.offer( reader );
  70                 }
  71         }
  72
  73 }