wbxmlencoder.java

WAP协议栈的JAVA实现

/**
 * JWAP - A Java Implementation of the WAP Protocols
 * Copyright (C) 2001-2004 Niko Bender
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package net.sourceforge.jwap.util.wbxml;

import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.XMLReaderFactory;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import java.util.Iterator;


/**
 * @author suvarna
 *
 */
public class WBXMLEncoder {
    private static WBXMLEncoder anInstance;
    private XMLContentHandler handler;
    private ByteArrayOutputStream tokenStream;

    private WBXMLEncoder() {
        initialize();
    }

    private void initialize() {
        tokenStream = new ByteArrayOutputStream();
    }

    public static WBXMLEncoder getInstance() {
        if (anInstance == null) {
            anInstance = new WBXMLEncoder();
        }

        return anInstance;
    }

    public OutputStream encode(InputStream xmlStream) {
        //		extractCharEncoding(xmlStream);
        try {
            XMLReader reader = XMLReaderFactory.createXMLReader();
            reader.setFeature("http://xml.org/sax/features/validation", false);
            handler = new XMLContentHandler(getEncodingFrom(xmlStream));
            reader.setContentHandler(handler);
            reader.setErrorHandler(handler);
            reader.setDTDHandler(handler);
            reader.setEntityResolver(handler);
            reader.setProperty("http://xml.org/sax/properties/lexical-handler",
                handler);

            InputSource xmlSource = new InputSource(xmlStream);

            //		reader.setFeature("http://xml.org/sax/features/validation",true);
            reader.parse(xmlSource);
        } catch (SAXException saxExp) {
            saxExp.printStackTrace();
        } catch (IOException ioExp) {
            ioExp.printStackTrace();
        }

        encodeProlog();
        encodeStringTable();
        encodeBody();

        return tokenStream;
    }

    private String getEncodingFrom(InputStream xmlStream) {
        /*        BufferedReader reader = new BufferedReader(new InputStreamReader(xmlStream));
                try {
                        String line = reader.readLine().trim();
                        while (line.length() == 0 || !line.startsWith("<?xml"))
                                line = reader.readLine();
                        if (line.startsWith("<?xml")) {
                                String remaining = line.split("encoding=\"")[1];
                                String encoding = remaining.substring(0, remaining.indexOf('"'));
                                reader.close();
                                return encoding;
                        }
                } catch (IOException ioExp) {
                        ioExp.printStackTrace();
                }
                */
        return "utf-8";
    }

    /**
     * Please refer BNF of document structure.
     * start = version publicid charset strtbl body
     *
     **/
    public void encodeProlog() {
        tokenStream.write(TokenRepository.getInstance().getWbxmlEncoding());
        tokenStream.write(PublicIdentifiers.getInstance()
                                           .getPublicIdentifierValue("UNKNOWN"));
        tokenStream.write(TokenRepository.getInstance().getCharEncoding());
        tokenStream.write(0); // string table length to do...
    }

    public void encodeBody() {
        Iterator tokens = handler.getTokens();

        while (tokens.hasNext()) {
            Token aToken = (Token) tokens.next();
            tokenStream.write(aToken.getValue());
        }
    }

    public void encodeStringTable() {
    }
}