Follow-up to [927d280]: make registerSystemIdFilename() more friendly to modules.

Author: carlosame

src/io/sf/carte/doc/xml/dtd/DefaultEntityResolver.java

@@ -97,73 +97,136 @@ public DefaultEntityResolver() {
 	 */
 	public DefaultEntityResolver(boolean enableWhitelist) {
 		super();
-		systemIdToFilename.put("https://www.w3.org/TR/html5/entities.dtd", "w3c/xhtml5.ent");
-		systemIdToFilename.put("http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd", "w3c/xhtml1-strict.dtd");
+		systemIdToFilename.put("https://www.w3.org/TR/html5/entities.dtd",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml5.ent");
+		systemIdToFilename.put("http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml1-strict.dtd");
 		systemIdToFilename.put("http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd",
-				"w3c/xhtml1-transitional.dtd");
-		systemIdToFilename.put("http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd", "w3c/xhtml11.dtd");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml11.dtd", "w3c/xhtml11.dtd");
-		systemIdToFilename.put("http://www.w3.org/TR/xhtml11/DTD/xhtml-lat1.ent", "w3c/xhtml-lat1.ent");
-		systemIdToFilename.put("http://www.w3.org/TR/xhtml11/DTD/xhtml-symbol.ent", "w3c/xhtml-symbol.ent");
-		systemIdToFilename.put("http://www.w3.org/TR/xhtml11/DTD/xhtml-special.ent", "w3c/xhtml-special.ent");
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml1-transitional.dtd");
+		systemIdToFilename.put("http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml11.dtd");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml11.dtd",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml11.dtd");
+		systemIdToFilename.put("http://www.w3.org/TR/xhtml11/DTD/xhtml-lat1.ent",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-lat1.ent");
+		systemIdToFilename.put("http://www.w3.org/TR/xhtml11/DTD/xhtml-symbol.ent",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-symbol.ent");
+		systemIdToFilename.put("http://www.w3.org/TR/xhtml11/DTD/xhtml-special.ent",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-special.ent");
 		// XHTML 1.1 modules
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-inlstyle-1.mod", "w3c/xhtml-inlstyle-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml11-model-1.mod", "w3c/xhtml-11-model-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-datatypes-1.mod", "w3c/xhtml-datatypes-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-framework-1.mod", "w3c/xhtml-framework-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-text-1.mod", "w3c/xhtml-text-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-hypertext-1.mod", "w3c/xhtml-hypertext-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-list-1.mod", "w3c/xhtml-list-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-edit-1.mod", "w3c/xhtml-edit-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-bdo-1.mod", "w3c/xhtml-bdo-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-ruby-1.mod", "w3c/xhtml-ruby-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-pres-1.mod", "w3c/xhtml-pres-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-link-1.mod", "w3c/xhtml-link-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-meta-1.mod", "w3c/xhtml-meta-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-base-1.mod", "w3c/xhtml-base-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-script-1.mod", "w3c/xhtml-script-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-style-1.mod", "w3c/xhtml-style-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-image-1.mod", "w3c/xhtml-image-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-csismap-1.mod", "w3c/xhtml-csismap-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-ssismap-1.mod", "w3c/xhtml-ssismap-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-param-1.mod", "w3c/xhtml-param-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-object-1.mod", "w3c/xhtml-object-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-table-1.mod", "w3c/xhtml-table-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-form-1.mod", "w3c/xhtml-form-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-legacy-1.mod", "w3c/xhtml-legacy-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-struct-1.mod", "w3c/xhtml-struct-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-inlstyle-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-inlstyle-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml11-model-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-11-model-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-datatypes-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-datatypes-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-framework-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-framework-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-text-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-text-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-hypertext-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-hypertext-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-list-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-list-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-edit-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-edit-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-bdo-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-bdo-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-ruby-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-ruby-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-pres-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-pres-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-link-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-link-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-meta-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-meta-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-base-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-base-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-script-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-script-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-style-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-style-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-image-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-image-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-csismap-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-csismap-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-ssismap-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-ssismap-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-param-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-param-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-object-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-object-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-table-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-table-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-form-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-form-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-legacy-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-legacy-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-struct-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-struct-1.mod");
 		// Other common DTDs
-		systemIdToFilename.put("http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd", "w3c/xhtml1-frameset.dtd");
-		systemIdToFilename.put("http://www.w3.org/TR/xhtml-basic/xhtml-basic11.dtd", "w3c/xhtml-basic11.dtd");
-		systemIdToFilename.put("http://www.w3.org/TR/html4/strict.dtd", "w3c/html4-strict.dtd");
-		systemIdToFilename.put("http://www.w3.org/TR/html4/loose.dtd", "w3c/html4-loose.dtd");
-		systemIdToFilename.put("http://www.w3.org/TR/html4/frameset.dtd", "w3c/html4-frameset.dtd");
-		systemIdToFilename.put("http://www.w3.org/Math/DTD/mathml2/mathml2.dtd", "w3c/mathml2.dtd");
-		systemIdToFilename.put("http://www.w3.org/Math/DTD/mathml1/mathml.dtd", "w3c/mathml.dtd");
-		systemIdToFilename.put("http://www.w3.org/2002/04/xhtml-math-svg/xhtml-math-svg.dtd", "w3c/xhtml-math-svg.dtd");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-inlstruct-1.mod", "w3c/xhtml-inlstruct-1.dtd");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-inlphras-1.mod", "w3c/xhtml-inlphras-1.dtd");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-blkstruct-1.mod", "w3c/xhtml-blkstruct-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-blkphras-1.mod", "w3c/xhtml-blkphras-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-applet-1.mod", "w3c/xhtml-applet-1.dtd");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-blkpres-1.mod", "w3c/xhtml-blkpres-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-basic-form-1.mod", "w3c/xhtml-basic-form-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-basic-table-1.mod", "w3c/xhtml-basic-table-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-frames-1.mod", "w3c/xhtml-frames-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-target-1.mod", "w3c/xhtml-target-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-iframe-1.mod", "w3c/xhtml-iframe-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-events-1.mod", "w3c/xhtml-events-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-nameident-1.mod", "w3c/xhtml-nameident-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-legacy-redecl-1.mod", "w3c/xhtml-legacy-redecl-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-inlpres-1.mod", "w3c/xhtml-inlpres-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-arch-1.mod", "w3c/xhtml-arch-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-notations-1.mod", "w3c/xhtml-notations-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-qname-1.mod", "w3c/xhtml-qname-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-attribs-1.mod", "w3c/xhtml-attribs-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-charent-1.mod", "w3c/xhtml-charent-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-basic11-model-1.mod", "w3c/xhtml-basic11-model-1.mod");
-		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-inputmode-1.mod", "w3c/xhtml-inputmode-1.mod");
-		systemIdToFilename.put("http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd", "w3c/svg11.dtd");
+		systemIdToFilename.put("http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml1-frameset.dtd");
+		systemIdToFilename.put("http://www.w3.org/TR/xhtml-basic/xhtml-basic11.dtd",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-basic11.dtd");
+		systemIdToFilename.put("http://www.w3.org/TR/html4/strict.dtd",
+				"/io/sf/carte/doc/xml/dtd/w3c/html4-strict.dtd");
+		systemIdToFilename.put("http://www.w3.org/TR/html4/loose.dtd",
+				"/io/sf/carte/doc/xml/dtd/w3c/html4-loose.dtd");
+		systemIdToFilename.put("http://www.w3.org/TR/html4/frameset.dtd",
+				"/io/sf/carte/doc/xml/dtd/w3c/html4-frameset.dtd");
+		systemIdToFilename.put("http://www.w3.org/Math/DTD/mathml2/mathml2.dtd",
+				"/io/sf/carte/doc/xml/dtd/w3c/mathml2.dtd");
+		systemIdToFilename.put("http://www.w3.org/Math/DTD/mathml1/mathml.dtd",
+				"/io/sf/carte/doc/xml/dtd/w3c/mathml.dtd");
+		systemIdToFilename.put("http://www.w3.org/2002/04/xhtml-math-svg/xhtml-math-svg.dtd",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-math-svg.dtd");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-inlstruct-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-inlstruct-1.dtd");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-inlphras-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-inlphras-1.dtd");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-blkstruct-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-blkstruct-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-blkphras-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-blkphras-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-applet-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-applet-1.dtd");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-blkpres-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-blkpres-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-basic-form-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-basic-form-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-basic-table-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-basic-table-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-frames-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-frames-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-target-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-target-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-iframe-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-iframe-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-events-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-events-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-nameident-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-nameident-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-legacy-redecl-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-legacy-redecl-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-inlpres-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-inlpres-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-arch-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-arch-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-notations-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-notations-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-qname-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-qname-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-attribs-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-attribs-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-charent-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-charent-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-basic11-model-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-basic11-model-1.mod");
+		systemIdToFilename.put("http://www.w3.org/MarkUp/DTD/xhtml-inputmode-1.mod",
+				"/io/sf/carte/doc/xml/dtd/w3c/xhtml-inputmode-1.mod");
+		systemIdToFilename.put("http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd",
+				"/io/sf/carte/doc/xml/dtd/w3c/svg11.dtd");
 		//
 		systemIdToPublicId.put("http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd", "-//W3C//DTD XHTML 1.0 Strict//EN");
 		systemIdToPublicId.put("http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd",
@@ -221,18 +284,18 @@ public InputSource getExternalSubset(String name, String baseURI) throws SAXExce
 	 * Register an internal classpath filename to retrieve a DTD {@code SystemId}.
 	 * 
 	 * @param systemId the {@code SystemId}.
-	 * @param filename the internal filename.
+	 * @param filename the internal filename. Must point to a resource with
+	 *                 {@code UTF-8} encoding.
 	 * @return {@code true} if the new {@code SystemId} was successfully registered,
 	 *         {@code false} if it was already registered.
 	 * @throws IllegalArgumentException if the {@code filename} is considered
-	 *                                  invalid by
-	 *                                  {@link #isInvalidInternalPath(String)}.
+	 *                                  invalid by {@link #isInvalidPath(String)}.
 	 */
 	protected boolean registerSystemIdFilename(String systemId, String filename) {
 		if (filename == null || systemId == null) {
 			throw new NullPointerException("Null SystemId or filename.");
 		}
-		if (isInvalidInternalPath(filename)) {
+		if (isInvalidPath(filename)) {
 			throw new IllegalArgumentException("Bad DTD filename.");
 		}
 		String ret;
@@ -242,21 +305,6 @@ protected boolean registerSystemIdFilename(String systemId, String filename) {
 		return ret == null;
 	}
 
-	/**
-	 * Determine if the given pathname is an invalid internal path.
-	 * <p>
-	 * The pathname must contain {@code /dtd/} and be a valid path according to
-	 * {@link #isInvalidPath(String)}.
-	 * </p>
-	 * 
-	 * @param pathname the classpath pathname to check. It is assumed to be
-	 *                 non-{@code null}.
-	 * @return {@code true} if the pathname is invalid.
-	 */
-	protected boolean isInvalidInternalPath(String pathname) {
-		return isInvalidPath(pathname) || !pathname.contains("/dtd/");
-	}
-
 	@Override
 	public final InputSource resolveEntity(String name, String publicId, String baseURI, String systemId)
 			throws SAXException, IOException {
@@ -456,24 +504,19 @@ public void setClassLoader(ClassLoader loader) {
 	}
 
 	private Reader loadDTDfromClasspath(final String dtdFilename) {
-		final String resPath;
-		if (dtdFilename.charAt(0) != '/') {
-			// relative
-			String pkgPath = DefaultEntityResolver.class.getPackage().getName().replace('.', '/');
-			StringBuilder buf = new StringBuilder(pkgPath.length() + dtdFilename.length() + 2);
-			buf.append('/').append(pkgPath).append('/').append(dtdFilename);
-			resPath = buf.toString();
-		} else {
-			resPath = dtdFilename;
-		}
 		InputStream is = java.security.AccessController.doPrivileged(new java.security.PrivilegedAction<InputStream>() {
 			@Override
 			public InputStream run() {
+				InputStream is;
 				if (loader != null) {
-					return loader.getResourceAsStream(resPath);
+					is = loader.getResourceAsStream(dtdFilename);
 				} else {
-					return this.getClass().getResourceAsStream(resPath);
+					is = DefaultEntityResolver.class.getResourceAsStream(dtdFilename);
+				}
+				if (is == null) {
+					is = ClassLoader.getSystemResourceAsStream(dtdFilename);
 				}
+				return is;
 			}
 		});
 		Reader re = null;