org.sonar.plugins.xml.parsers.DetectSchemaParser.java Source code

Introduction

Here is the source code for org.sonar.plugins.xml.parsers.DetectSchemaParser.java

Source

/*
 * Sonar XML Plugin
 * Copyright (C) 2010 Matthijs Galesloot
 * dev@sonar.codehaus.org
 *
 * Licensed 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.sonar.plugins.xml.parsers;

import java.io.IOException;
import java.io.InputStream;

import javax.xml.parsers.SAXParser;

import org.apache.commons.io.IOUtils;
import org.apache.xerces.impl.Constants;
import org.sonar.api.utils.SonarException;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.XMLReader;
import org.xml.sax.ext.LexicalHandler;
import org.xml.sax.helpers.DefaultHandler;

/**
 * Parse the file quickly only to detect the sDTD or Schema.
 * 
 * @author Matthijs Galesloot
 * @since 1.0
 */
public final class DetectSchemaParser extends AbstractParser {

    /**
     * Doctype declaration in a Document.
     */
    public static class Doctype {

        private String dtd;
        private String namespace;

        public String getDtd() {
            return dtd;
        }

        public String getNamespace() {
            return namespace;
        }
    }

    /**
     * Exception to stop the parser from further processing.  
     */
    private static class StopParserException extends SAXException {

        private static final long serialVersionUID = 1L;

    }

    private static class Handler extends DefaultHandler implements LexicalHandler {

        private Doctype doctype = new Doctype();

        public void comment(char[] arg0, int arg1, int arg2) throws SAXException {
            // empty
        }

        public void endCDATA() throws SAXException {
            // empty
        }

        public void endDTD() throws SAXException {
            // empty
        }

        public void endEntity(String name) throws SAXException {
            // empty
        }

        @Override
        public void fatalError(SAXParseException e) throws SAXException {
            // ignore
        }

        public void startCDATA() throws SAXException {
            // empty
        }

        public void startDTD(String name, String publicId, String systemId) throws SAXException {
            doctype.dtd = publicId;
        }

        @Override
        public void startElement(String uri, String localName, String qName, Attributes attributes)
                throws SAXException {
            doctype.namespace = attributes.getValue("xmlns");

            // we are done, cause the parser to stop
            throw new StopParserException();
        }

        public void startEntity(String name) throws SAXException {
            // empty
        }
    }

    /**
     * Find the Doctype (DTD or schema).
     */
    public Doctype findDoctype(InputStream input) {
        Handler handler = new Handler();

        try {
            SAXParser parser = newSaxParser();
            XMLReader xmlReader = parser.getXMLReader();
            xmlReader.setFeature(Constants.XERCES_FEATURE_PREFIX + "continue-after-fatal-error", true);
            xmlReader.setProperty("http://xml.org/sax/properties/lexical-handler", handler);
            parser.parse(input, handler);
            return handler.doctype;
        } catch (IOException e) {
            throw new SonarException(e);
        } catch (StopParserException e) {
            return handler.doctype;
        } catch (SAXException e) {
            throw new SonarException(e);
        } finally {
            IOUtils.closeQuietly(input);
        }
    }
}