private static NamespaceHandler wrapIfNeeded()

in blueprint/blueprint-core/src/main/java/org/apache/aries/blueprint/namespace/NamespaceHandlerRegistryImpl.java [747:813]
65 lines of code
13 McCabe index (conditional complexity)

    private static NamespaceHandler wrapIfNeeded(final NamespaceHandler handler) {
        URL result = null;
        try {
            result = handler.getSchemaLocation("");
        } catch (Throwable t) {
            // Ignore
        }
        if (result != null) {
            LOGGER.warn("NamespaceHandler " + handler.getClass().getName() + " is behaving badly and should be fixed");
            final URL res = result;
            return new NamespaceHandler() {
                final ConcurrentMap<String, Boolean> cache = new ConcurrentHashMap<String, Boolean>();
                @Override
                public URL getSchemaLocation(String s) {
                    URL url = handler.getSchemaLocation(s);
                    if (url != null && url.equals(res)) {
                        Boolean v, newValue;
                        Boolean valid = ((v = cache.get(s)) == null &&
                                (newValue = isValidSchema(s, url)) != null &&
                                (v = cache.putIfAbsent(s, newValue)) == null) ? newValue : v;
                        return valid ? url : null;
                    }
                    return url;
                }
                @Override
                public Set<Class> getManagedClasses() {
                    return handler.getManagedClasses();
                }
                @Override
                public Metadata parse(Element element, ParserContext parserContext) {
                    return handler.parse(element, parserContext);
                }
                @Override
                public ComponentMetadata decorate(Node node, ComponentMetadata componentMetadata, ParserContext parserContext) {
                    return handler.decorate(node, componentMetadata, parserContext);
                }
                private boolean isValidSchema(String ns, URL url) {
                    try {
                        InputStream is = url.openStream();
                        try {
                            XMLStreamReader reader = XMLInputFactory.newInstance().createXMLStreamReader(is);
                            try {
                                reader.nextTag();
                                String nsuri = reader.getNamespaceURI();
                                String name = reader.getLocalName();
                                if ("http://www.w3.org/2001/XMLSchema".equals(nsuri) && "schema".equals(name)) {
                                    String target = reader.getAttributeValue(null, "targetNamespace");
                                    if (ns.equals(target)) {
                                        return true;
                                    }
                                }
                            } finally {
                                reader.close();
                            }
                        } finally {
                            is.close();
                        }
                    } catch (Throwable t) {
                        // Ignore
                    }
                    return false;
                }
            };
        } else {
            return handler;
        }
    }