Problem parsing XML with schema when extracted from a jar file

Question

I am having a problem parsing XML with a schema, both of which are extracted from a jar file. I am using using ZipFile to get InputStream objects for the appropriate ZipEntry objects in the jar file. My XML is encrypted so I decrypt it to a temporary file. I am then attempting to parse the temporary file with the schema using DocumentBuilder.parse.
I get the following exception:
org.xml.sax.SAXParseException: cvc-elt.1: Cannot find the declaration of element '<root element name>'
This was all working OK before I jarred everything (i.e. when I was using standalone files, rather than InputStreams retrieved from a jar).
I have output the retrieved XML to a file and compared it with my original source and they are identical.
I am baffled because the nature of the exception suggests that the schema has been read and parsed correctly but the XML file is not parsing against the schema.
Any suggestions?
The code is as follows:
  public void open(File input) throws IOException, CSLXMLException {
    InputStream schema = ZipFileHandler.getResourceAsStream("<jar file name>", "<schema resource name>");
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder = null;
    try {
      factory.setNamespaceAware(true);
      factory.setValidating(true);
      factory.setAttribute(JAXP_SCHEMA_LANGUAGE, W3C_XML_SCHEMA);
      factory.setAttribute(JAXP_SCHEMA_SOURCE, schema);
      builder = factory.newDocumentBuilder();
      builder.setErrorHandler(new CSLXMLParseHandler());
    } catch (Exception builderException) {
      throw new CSLXMLException("Error setting up SAX: " + builderException.toString());
    Document document = null;
    try {
      document = builder.parse(input);
    } catch (SAXException parseException) {
      throw new CSLXMLException(parseException.toString());
    }

Answer 1

I was originally using getSystemResource, which worked fine until I jarred the application. The problem appears to be that resources returned from a jar file cannot be used in the same way as resources returned directly from the file system. You have to use the ZipFile class (or its JarFile subclass) to locate the ZipEntry in the jar file and then use ZipFile.getInputStream(ZipEntry) to convert this to an InputStream. I have seen example code where an InputStream is used for the JAXP_SCHEMA_SOURCE attribute but, for some reason, this did not work with the InputStream returned by ZipFile.getInputStream. Like you, I have also seen examples that use a URL but they appear to be URL's that point to a file not URL's that point to an entry in a jar file.
Maybe there is another way around this but writing to a file works and I set use File.deleteOnExit() to ensure things are tidied afterwards.