FULL PRODUCT VERSION :
java version "1.4.2_06"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2_06-b03)
Java HotSpot(TM) Client VM (build 1.4.2_06-b03, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
The error occurs within pure Java code.
It was discovered on Windows XP:

Microsoft Windows XP [Version 5.1.2600]

A DESCRIPTION OF THE PROBLEM :
The implementation of XMLReader.parse(InputSource) closes the input stream before returning.

Aside from not being specified in the documentation, it is an incorrect assumption to make that the parser is responsible for closing a file.

When using file locks, this bug causes the file to be unlocked prematurely.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Create a FileInputStream to a well-formed XML document.
Get the stream's channel.
Use an XMLReader to parse the stream.
Try to access the stream's channel again (e.g. channel.position() ).

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The channel should still be open.
ACTUAL -
The channel is not open, because the input stream passed to the XMLReader was closed by the XMLReader implementation and closing an InputStream also closes any Channels associated with it.

Calls on the channel (e.g. channel.position()) will throw a ClosedChannelException.
This also means any FileLocks held on the file are now invalid.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import org.xml.sax.InputSource;
import org.xml.sax.XMLReader;

import java.io.File;
import java.io.FileInputStream;
import java.nio.channels.FileChannel;

import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

public class
Test
{
   public static void
   main(String[] argv)
   {
      if (argv.length != 1)
      {
         System.err.println("Usage: <jvm> Test <xml_file>");
         System.exit(1);
      }

      try
      {
         // Open the file
         File file = new File(argv[0]);
         FileInputStream fileIn = new FileInputStream(file);
         FileChannel fileChannel = fileIn.getChannel();

         // Create an XMLReader
         InputSource inputSource = new InputSource(fileIn);
         SAXParserFactory saxParserFactory = SAXParserFactory.newInstance();
         SAXParser saxParser = saxParserFactory.newSAXParser();
         XMLReader xmlReader = saxParser.getXMLReader();

         // Parse it
         System.out.println("fileChannel.isOpen() = " + fileChannel.isOpen());
         xmlReader.parse(inputSource);
         System.out.println("fileChannel.isOpen() = " + fileChannel.isOpen());
      }
      catch (Exception e)
      {
         e.printStackTrace();
      }
      finally
      {
         System.exit(0);
      }
   }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
This can be worked around by passing to the XMLReader a FilteredInputSource that ignores calls to close():

         FileInputStream fileIn = new FileInputStream(file);

         FilterInputStream nonClosingInputStream = new FilterInputStream(fileIn)
         {
            public void
            close()
            throws IOException
            {
               // Ignore
            }
         };

         InputSource inputSource = new InputSource(nonClosingInputStream);