001/*
002 * Syncany, www.syncany.org
003 * Copyright (C) 2011-2016 Philipp C. Heckel <philipp.heckel@gmail.com> 
004 *
005 * This program is free software: you can redistribute it and/or modify
006 * it under the terms of the GNU General Public License as published by
007 * the Free Software Foundation, either version 3 of the License, or
008 * (at your option) any later version.
009 *
010 * This program is distributed in the hope that it will be useful,
011 * but WITHOUT ANY WARRANTY; without even the implied warranty of
012 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
013 * GNU General Public License for more details.
014 *
015 * You should have received a copy of the GNU General Public License
016 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
017 */
018package org.syncany.database.dao;
019
020import java.io.File;
021import java.io.FileInputStream;
022import java.io.FileOutputStream;
023import java.io.IOException;
024import java.io.InputStream;
025import java.io.OutputStreamWriter;
026import java.io.PrintWriter;
027import java.util.Iterator;
028import java.util.List;
029import java.util.logging.Level;
030import java.util.logging.Logger;
031
032import javax.xml.parsers.SAXParser;
033import javax.xml.parsers.SAXParserFactory;
034import javax.xml.stream.XMLStreamException;
035
036import org.syncany.chunk.Transformer;
037import org.syncany.database.DatabaseVersion;
038import org.syncany.database.MemoryDatabase;
039import org.syncany.database.VectorClock;
040
041/**
042 * Serializes a {@link MemoryDatabase} or a list of {@link DatabaseVersion}s to an 
043 * XML-based file format, using a {@link Transformer} to compress/encrypt the file 
044 * before writing, and to decompress/decrypt it before reading.
045 * 
046 * <p>The class offers a variety of <code>save()</code> to serialize and store a memory
047 * database to a file, and several <code>load()</code> methods to load them from disk.
048 * 
049 * <p>It uses a {@link DatabaseXmlWriter} to write XML files to disk and 
050 * {@link DatabaseXmlParseHandler} to parse them while reading. 
051 * 
052 * @see DatabaseXmlParseHandler
053 * @see DatabaseXmlWriter
054 * @author Philipp C. Heckel (philipp.heckel@gmail.com)
055 */
056public class DatabaseXmlSerializer {
057        private static final Logger logger = Logger.getLogger(DatabaseXmlSerializer.class.getSimpleName());
058
059        public enum DatabaseReadType {
060                FULL, HEADER_ONLY
061        }
062
063        private Transformer transformer;
064
065        public DatabaseXmlSerializer() {
066                this(null);
067        }
068
069        public DatabaseXmlSerializer(Transformer transformer) {
070                this.transformer = transformer;
071        }
072
073        public void save(List<DatabaseVersion> databaseVersions, File destinationFile) throws IOException {
074                save(databaseVersions.iterator(), destinationFile);
075        }
076
077        public void save(Iterator<DatabaseVersion> databaseVersions, File destinationFile) throws IOException {
078                try {
079                        PrintWriter out;
080
081                        if (transformer == null) {
082                                out = new PrintWriter(new OutputStreamWriter(
083                                                new FileOutputStream(destinationFile), "UTF-8"));
084                        }
085                        else {
086                                out = new PrintWriter(new OutputStreamWriter(
087                                                transformer.createOutputStream(new FileOutputStream(destinationFile)), "UTF-8"));
088                        }
089
090                        // Initialize XML writer
091                        new DatabaseXmlWriter(databaseVersions, out).write();
092                }
093                catch (XMLStreamException e) {
094                        throw new IOException(e);
095                }
096        }
097
098        public void load(MemoryDatabase db, File databaseFile, VectorClock fromVersion, VectorClock toVersion, DatabaseReadType readType)
099                        throws IOException {
100                
101                InputStream is;
102
103                if (transformer == null) {
104                        is = new FileInputStream(databaseFile);
105                }
106                else {
107                        is = transformer.createInputStream(new FileInputStream(databaseFile));
108                }
109
110                try {
111                        logger.log(Level.INFO, "- Loading database ({0}) from file {1} ...", new Object[] { readType, databaseFile });
112
113                        SAXParserFactory factory = SAXParserFactory.newInstance();
114                        SAXParser saxParser = factory.newSAXParser();
115
116                        saxParser.parse(is, new DatabaseXmlParseHandler(db, fromVersion, toVersion, readType));
117                }
118                catch (Exception e) {
119                        throw new IOException(e);
120                }
121        }
122
123}