bundles/org.apache.jasper.glassfish/src/org/apache/jasper/compiler/ParserController.java
private void determineSyntaxAndEncoding(String absFileName,
					    JarFile jarFile,
					    String jspConfigPageEnc)
	        throws JasperException, IOException {

	isXml = false;

	/*
	 * 'true' if the syntax (XML or standard) of the file is given
	 * from external information: either via a JSP configuration element,
	 * the ".jspx" suffix, or the enclosing file (for included resources)
	 */
	boolean isExternal = false;

	/*
	 * Indicates whether we need to revert from temporary usage of
	 * "ISO-8859-1" back to "UTF-8"
	 */
	boolean revert = false;

        JspConfig jspConfig = ctxt.getOptions().getJspConfig();
        JspProperty jspProperty = jspConfig.findJspProperty(absFileName);
        if (jspProperty.isXml() != null) {
            // If <is-xml> is specified in a <jsp-property-group>, it is used.
            isXml = JspUtil.booleanValue(jspProperty.isXml());
	    isExternal = true;
	} else if (absFileName.endsWith(".jspx")
		   || absFileName.endsWith(".tagx")) {
	    isXml = true;
	    isExternal = true;
	}
	
	if (isExternal && !isXml) {
	    // JSP (standard) syntax. Use encoding specified in jsp-config
	    // if provided.
	    sourceEnc = jspConfigPageEnc;
	    if (sourceEnc != null) {
		return;
	    }
	    // We don't know the encoding
	    sourceEnc = "ISO-8859-1";
	} else {
	    // XML syntax or unknown, (auto)detect encoding ...
	    Object[] ret = XMLEncodingDetector.getEncoding(absFileName,
							   jarFile, ctxt, err);
	    sourceEnc = (String) ret[0];
	    if (((Boolean) ret[1]).booleanValue()) {
		isEncodingSpecifiedInProlog = true;
	    }
	    if (ret[2] != null && ((Boolean) ret[2]).booleanValue()) {
                hasBom = true;
	    }

	    if (!isXml && sourceEnc.equalsIgnoreCase("utf-8") && !hasBom) {
		/*
		 * We don't know if we're dealing with XML or standard syntax.
		 * Therefore, we need to check to see if the page contains
		 * a <jsp:root> element.
		 *
                 * We need to be careful, because the page may be encoded in
                 * ISO-8859-1 (or something entirely different: UTF-8 was 
                 * chosen as the default, for lack of better alternative),
                 * and may contain byte sequences that will cause a UTF-8
                 * converter to throw exceptions. 
		 *
		 * It is safe to use a source encoding of ISO-8859-1 in this
		 * case, as there are no invalid byte sequences in ISO-8859-1,
		 * and the byte/character sequences we're looking for (i.e.,
		 * <jsp:root>) are identical in either encoding (both UTF-8
		 * and ISO-8859-1 are extensions of ASCII).
		 */
		sourceEnc = "ISO-8859-1";
		revert = true;
	    }
	}

	if (isXml) {
	    // (This implies 'isExternal' is TRUE.)
	    // We know we're dealing with a JSP document (via JSP config or
	    // ".jspx" suffix), so we're done.
	    return;
	}

	/*
	 * At this point, 'isExternal' or 'isXml' is FALSE.
	 * Search for jsp:root action, in order to determine if we're dealing 
	 * with XML or standard syntax (unless we already know what we're 
	 * dealing with, i.e., when 'isExternal' is TRUE and 'isXml' is FALSE).
	 * No check for XML prolog, since nothing prevents a page from
	 * outputting XML and still using JSP syntax (in this case, the 
	 * XML prolog is treated as template text).
	 */
	JspReader jspReader = null;
	try {
	    jspReader = new JspReader(ctxt, absFileName, sourceEnc, jarFile,
				      err);
	} catch (FileNotFoundException ex) {
	    throw new JasperException(ex);
	}
        jspReader.setSingleFile(true);
        Mark startMark = jspReader.mark();
	if (!isExternal) {
	    jspReader.reset(startMark);
	    if (hasJspRoot(jspReader)) {
	        isXml = true;
		if (revert) sourceEnc = "UTF-8";
		return;
	    } else {
	        isXml = false;
	    }
	}

	/*
	 * At this point, we know we're dealing with JSP syntax.
	 * If an XML prolog is provided, it's treated as template text.
	 * Determine the page encoding from the page directive, unless it's
	 * specified via JSP config.
	 */
        if (!hasBom) {
            sourceEnc = jspConfigPageEnc;
        }
	if (sourceEnc == null) {
	    sourceEnc = getPageEncodingForJspSyntax(jspReader, startMark);
	    if (sourceEnc == null) {
		// Default to "ISO-8859-1" per JSP spec
		sourceEnc = "ISO-8859-1";
		isDefaultPageEncoding = true;
	    }
	}
    }
private void determineSyntaxAndEncoding(String absFileName,
					    JarFile jarFile,
					    String jspConfigPageEnc)
	        throws JasperException, IOException {

	isXml = false;

	/*
	 * 'true' if the syntax (XML or standard) of the file is given
	 * from external information: either via a JSP configuration element,
	 * the ".jspx" suffix, or the enclosing file (for included resources)
	 */
	boolean isExternal = false;

	/*
	 * Indicates whether we need to revert from temporary usage of
	 * "ISO-8859-1" back to "UTF-8"
	 */
	boolean revert = false;

        JspConfig jspConfig = ctxt.getOptions().getJspConfig();
        JspProperty jspProperty = jspConfig.findJspProperty(absFileName);
        if (jspProperty.isXml() != null) {
            // If <is-xml> is specified in a <jsp-property-group>, it is used.
            isXml = JspUtil.booleanValue(jspProperty.isXml());
	    isExternal = true;
	} else if (absFileName.endsWith(".jspx")
		   || absFileName.endsWith(".tagx")) {
	    isXml = true;
	    isExternal = true;
	}
	
	if (isExternal && !isXml) {
	    // JSP (standard) syntax. Use encoding specified in jsp-config
	    // if provided.
	    sourceEnc = jspConfigPageEnc;
	    if (sourceEnc != null) {
		return;
	    }
	    // We don't know the encoding
	    sourceEnc = "ISO-8859-1";
	} else {
	    // XML syntax or unknown, (auto)detect encoding ...
	    Object[] ret = XMLEncodingDetector.getEncoding(absFileName,
							   jarFile, ctxt, err);
	    sourceEnc = (String) ret[0];
	    if (((Boolean) ret[1]).booleanValue()) {
		isEncodingSpecifiedInProlog = true;
	    }
	    if (ret[2] != null && ((Boolean) ret[2]).booleanValue()) {
                hasBom = true;
	    }

	    if (!isXml && sourceEnc.equalsIgnoreCase("utf-8") && !hasBom) {
		/*
		 * We don't know if we're dealing with XML or standard syntax.
		 * Therefore, we need to check to see if the page contains
		 * a <jsp:root> element.
		 *
                 * We need to be careful, because the page may be encoded in
                 * ISO-8859-1 (or something entirely different: UTF-8 was 
                 * chosen as the default, for lack of better alternative),
                 * and may contain byte sequences that will cause a UTF-8
                 * converter to throw exceptions. 
		 *
		 * It is safe to use a source encoding of ISO-8859-1 in this
		 * case, as there are no invalid byte sequences in ISO-8859-1,
		 * and the byte/character sequences we're looking for (i.e.,
		 * <jsp:root>) are identical in either encoding (both UTF-8
		 * and ISO-8859-1 are extensions of ASCII).
		 */
		sourceEnc = "ISO-8859-1";
		revert = true;
	    }
	}

	if (isXml) {
	    // (This implies 'isExternal' is TRUE.)
	    // We know we're dealing with a JSP document (via JSP config or
	    // ".jspx" suffix), so we're done.
	    return;
	}

	/*
	 * At this point, 'isExternal' or 'isXml' is FALSE.
	 * Search for jsp:root action, in order to determine if we're dealing 
	 * with XML or standard syntax (unless we already know what we're 
	 * dealing with, i.e., when 'isExternal' is TRUE and 'isXml' is FALSE).
	 * No check for XML prolog, since nothing prevents a page from
	 * outputting XML and still using JSP syntax (in this case, the 
	 * XML prolog is treated as template text).
	 */
	JspReader jspReader = null;
	try {
	    jspReader = new JspReader(ctxt, absFileName, sourceEnc, jarFile,
				      err);
	} catch (FileNotFoundException ex) {
	    throw new JasperException(ex);
	}
        jspReader.setSingleFile(true);
        Mark startMark = jspReader.mark();
	if (!isExternal) {
	    jspReader.reset(startMark);
	    if (hasJspRoot(jspReader)) {
	        isXml = true;
		if (revert) sourceEnc = "UTF-8";
		return;
	    } else {
	        isXml = false;
	    }
	}

	/*
	 * At this point, we know we're dealing with JSP syntax.
	 * If an XML prolog is provided, it's treated as template text.
	 * Determine the page encoding from the page directive, unless it's
	 * specified via JSP config.
	 */
        if (!hasBom) {
            sourceEnc = jspConfigPageEnc;
        }
	if (sourceEnc == null) {
	    sourceEnc = getPageEncodingForJspSyntax(jspReader, startMark);
	    if (sourceEnc == null) {
		// Default to "ISO-8859-1" per JSP spec
		sourceEnc = "ISO-8859-1";
		isDefaultPageEncoding = true;
	    }
	}
    }
Determines the syntax (standard or XML) and page encoding properties
for the given file, and stores them in the 'isXml' and 'sourceEnc'
instance variables, respectively.