import java.io.IOException;

import java.io.InputStream;

import java.io.Reader;

import java.util.ArrayList;

import java.util.Collections;

import java.util.List;

import javax.xml.transform.stream.StreamSource;

import org.w3c.dom.ls.LSInput;

import org.w3c.dom.ls.LSResourceResolver;

    private final boolean createResolver;

    private final String resourceName;

    private final Class<?> clazz;

    public SchemaCache(String resourceName, Class<?> classToResolveResources) {

        this(resourceName, classToResolveResources, false);

    }

    public SchemaCache(String resourceName, Class<?> classToResolveResources, boolean createResolver) {

        this.resourceName = resourceName;

        this.createResolver = createResolver;

        this.clazz = classToResolveResources;

        if (schema==null) {

            synchronized (this) {

                if (schema == null) {

                    ResourceResolver resourceResolver = null;

                    try (InputStream is = clazz.getResourceAsStream(resourceName)) {

                        StreamSource source = new StreamSource(is);

                        source.setSystemId(resourceName);

                        // do not disable secure processing - these are well-known schemas

                        SchemaFactory sf = XmlFactory.createSchemaFactory(XMLConstants.W3C_XML_SCHEMA_NS_URI, false);

                        SchemaFactory schemaFactory = allowExternalAccess(sf, "file", false);

                        if (createResolver) {

                            resourceResolver = new ResourceResolver(clazz);

                            schemaFactory.setResourceResolver(resourceResolver);

                        }

                        schema = schemaFactory.newSchema(source);

                    } catch (IOException | SAXException e) {

                        throw new InternalError(e);

                    } finally {

                        if (resourceResolver != null) resourceResolver.closeStreams();

                    }

                }

            }

        }

        return schema.newValidatorHandler();

    }

    class ResourceResolver implements LSResourceResolver {

        private List<InputStream> streamsToClose = Collections.synchronizedList(new ArrayList<InputStream>());

        private Class<?> clazz;

        ResourceResolver(Class<?> clazz) {

            this.clazz = clazz;

        }

        @Override

        public LSInput resolveResource(String type, String namespaceURI, String publicId, String systemId, String baseURI) {

            // XSOM passes the namespace URI to the publicID parameter.

            // we do the same here .

            InputStream is = clazz.getResourceAsStream(systemId);

            streamsToClose.add(is);

            return new Input(is, publicId, systemId);

        }

        void closeStreams() {

            for (InputStream is : streamsToClose) {

                if (is != null) {

                    try {

                        is.close();

                    } catch (IOException e) {

                        // nothing to do ...

                    }

class Input implements LSInput {

    private InputStream is;

    private String publicId;

    private String systemId;

    public Input(InputStream is, String publicId, String systemId) {

        this.is = is;

        this.publicId = publicId;

        this.systemId = systemId;

    }

    @Override

    public Reader getCharacterStream() {

        return null;

    }

    @Override

    public void setCharacterStream(Reader characterStream) {

    }

    @Override

    public InputStream getByteStream() {

        return is;

    }

    @Override

    public void setByteStream(InputStream byteStream) {

    }

    @Override

    public String getStringData() {

        return null;

    }

    @Override

    public void setStringData(String stringData) {

    }

    @Override

    public String getSystemId() {

        return systemId;

    }

    @Override

    public void setSystemId(String systemId) {

    }

    @Override

    public String getPublicId() {

        return publicId;

    }

    @Override

    public void setPublicId(String publicId) {

    }

    @Override

    public String getBaseURI() {

        return null;

    }

    @Override

    public void setBaseURI(String baseURI) {

    }

    @Override

    public String getEncoding() {

        return null;

    }

    @Override

    public void setEncoding(String encoding) {

    }

    @Override

    public boolean getCertifiedText() {

        return false;

    }

    @Override

    public void setCertifiedText(boolean certifiedText) {

    }

}