org.apache.shindig.social.opensocial.util.XSDValidator.java Source code

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Here is the source code for org.apache.shindig.social.opensocial.util.XSDValidator.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations under the License.
 */
package org.apache.shindig.social.opensocial.util;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.w3c.dom.ls.LSInput;
import org.w3c.dom.ls.LSResourceResolver;
import org.xml.sax.SAXException;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;

import javax.xml.parsers.SAXParserFactory;
import javax.xml.transform.stream.StreamSource;
import javax.xml.validation.Schema;
import javax.xml.validation.SchemaFactory;
import javax.xml.validation.Validator;

/**
 * Validator utility for testing.
 */
public class XSDValidator {
    /**
     * The schema language being used.
     */
    private static final String W3C_XML_SCHEMA = "http://www.w3.org/2001/XMLSchema";

    /**
     * The XML declaration
     */
    public static final String XMLDEC = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n";

    protected static final Log log = LogFactory.getLog(XSDValidator.class);

    /**
     * Validate a xml string against a supplied schema.
     *
     * @param xml
     *          the xml presented as a string
     * @param schema
     *          an input stream containing the xsd
     * @return a list of errors or a 0 lenght string if none.
     */
    public static String validate(String xml, InputStream schema) {
        try {
            return validate(new ByteArrayInputStream(xml.getBytes("UTF-8")), schema);
        } catch (UnsupportedEncodingException e) {
            return e.getMessage();
        }
    }

    /**
     * Validate a xml input stream against a supplied schema.
     *
     * @param xml
     *          a stream containing the xml
     * @param schema
     *          a stream containing the schema
     * @return a list of errors or warnings, a 0 lenght string if none.
     */
    public static String validate(InputStream xml, InputStream schema) {

        SAXParserFactory factory = SAXParserFactory.newInstance();
        factory.setNamespaceAware(true);
        factory.setValidating(true);
        final StringBuilder errors = new StringBuilder();
        try {
            SchemaFactory schemaFactory = SchemaFactory.newInstance(W3C_XML_SCHEMA);
            Schema s = schemaFactory.newSchema(new StreamSource(schema));

            Validator validator = s.newValidator();
            final LSResourceResolver lsr = validator.getResourceResolver();
            validator.setResourceResolver(new LSResourceResolver() {

                public LSInput resolveResource(String arg0, String arg1, String arg2, String arg3, String arg4) {
                    log.info("resolveResource(" + arg0 + ',' + arg1 + ',' + arg2 + ',' + arg3 + ',' + arg4 + ')');
                    return lsr.resolveResource(arg0, arg1, arg2, arg3, arg4);
                }

            });

            validator.validate(new StreamSource(xml));
        } catch (IOException e) {
        } catch (SAXException e) {
            errors.append(e.getMessage()).append('\n');
        }

        return errors.toString();
    }

    /**
     * Process the response string to strip the container element and insert the
     * opensocial schema.
     *
     * @param xml
     * @return
     */
    public static String insertSchema(String xml, String schemaStatement, boolean removeContainer) {
        if (xml == null || xml.trim().length() == 0) {
            return xml;
        }

        if (removeContainer) {
            if (xml.startsWith("<response>")) {
                xml = xml.substring("<response>".length());
            }
            if (xml.endsWith("</response>")) {
                xml = xml.substring(0, xml.length() - "</response>".length());
            }
        }
        xml = xml.trim();

        int start = 0;
        if (xml.startsWith("<?")) {
            start = xml.indexOf('>') + 1;
            int gt = xml.indexOf('>', start);
            if (gt > 0) {
                return xml.substring(0, gt) + schemaStatement + xml.substring(gt);
            }
        } else {
            int gt = xml.indexOf('>', start);
            if (gt > 0) {
                return XMLDEC + xml.substring(0, gt) + schemaStatement + xml.substring(gt);
            }

        }
        return xml;
    }

    /**
     * @param xmlFragment
     * @return a list of errors
     */
    public static String validate(String xmlFragment, String schemaStatement, String schemaResource,
            boolean removeContainer) {
        String xml = XSDValidator.insertSchema(xmlFragment, schemaStatement, removeContainer);
        log.debug("Valiating " + xml);
        String errors = XSDValidator.validate(xml, XSDValidator.class.getResourceAsStream(schemaResource));
        if (!"".equals(errors)) {
            log.error("Failed to validate " + xml);
        }
        if (!"".equals(errors)) {
            throw new Error("XML document does not validate \n" + errors + '\n' + xml);
        }
        return xml;
    }

}