Java tutorial
/* * Syncany, www.syncany.org * Copyright (C) 2011-2015 Philipp C. Heckel <philipp.heckel@gmail.com> * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program 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 General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ package org.syncany.database.dao; import java.io.UnsupportedEncodingException; import java.util.Date; import java.util.logging.Level; import java.util.logging.Logger; import org.apache.commons.codec.binary.Base64; import org.syncany.database.ChunkEntry; import org.syncany.database.ChunkEntry.ChunkChecksum; import org.syncany.database.DatabaseVersion; import org.syncany.database.FileContent; import org.syncany.database.FileContent.FileChecksum; import org.syncany.database.FileVersion; import org.syncany.database.FileVersion.FileStatus; import org.syncany.database.FileVersion.FileType; import org.syncany.database.MemoryDatabase; import org.syncany.database.MultiChunkEntry; import org.syncany.database.MultiChunkEntry.MultiChunkId; import org.syncany.database.PartialFileHistory; import org.syncany.database.PartialFileHistory.FileHistoryId; import org.syncany.database.VectorClock; import org.syncany.database.VectorClock.VectorClockComparison; import org.syncany.database.dao.DatabaseXmlSerializer.DatabaseReadType; import org.xml.sax.Attributes; import org.xml.sax.SAXException; import org.xml.sax.helpers.DefaultHandler; /** * This class is used by the {@link DatabaseXmlSerializer} to read an XML-based * database file from disk. It extends a {@link DefaultHandler} used by a * SAX parser. * * <p>The class can read either an entire file into memory, or only parts of it -- * excluding contents (headers only) or only selecting certain database version * types (DEFAULT or PURGE). * * @see DatabaseXmlSerializer * @author Philipp C. Heckel <philipp.heckel@gmail.com> */ public class DatabaseXmlParseHandler extends DefaultHandler { private static final Logger logger = Logger.getLogger(DatabaseXmlParseHandler.class.getSimpleName()); private MemoryDatabase database; private VectorClock versionFrom; private VectorClock versionTo; private DatabaseReadType readType; private String elementPath; private DatabaseVersion databaseVersion; private VectorClock vectorClock; private boolean vectorClockInLoadRange; private FileContent fileContent; private MultiChunkEntry multiChunk; private PartialFileHistory fileHistory; public DatabaseXmlParseHandler(MemoryDatabase database, VectorClock fromVersion, VectorClock toVersion, DatabaseReadType readType) { this.elementPath = ""; this.database = database; this.versionFrom = fromVersion; this.versionTo = toVersion; this.readType = readType; } @Override public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException { elementPath += "/" + qName; if (elementPath.equalsIgnoreCase("/database/databaseVersions/databaseVersion")) { databaseVersion = new DatabaseVersion(); } else if (elementPath.equalsIgnoreCase("/database/databaseVersions/databaseVersion/header/time")) { Date timeValue = new Date(Long.parseLong(attributes.getValue("value"))); databaseVersion.setTimestamp(timeValue); } else if (elementPath.equalsIgnoreCase("/database/databaseVersions/databaseVersion/header/client")) { String clientName = attributes.getValue("name"); databaseVersion.setClient(clientName); } else if (elementPath.equalsIgnoreCase("/database/databaseVersions/databaseVersion/header/vectorClock")) { vectorClock = new VectorClock(); } else if (elementPath .equalsIgnoreCase("/database/databaseVersions/databaseVersion/header/vectorClock/client")) { String clientName = attributes.getValue("name"); Long clientValue = Long.parseLong(attributes.getValue("value")); vectorClock.setClock(clientName, clientValue); } else if (readType == DatabaseReadType.FULL) { if (elementPath.equalsIgnoreCase("/database/databaseVersions/databaseVersion/chunks/chunk")) { String chunkChecksumStr = attributes.getValue("checksum"); ChunkChecksum chunkChecksum = ChunkChecksum.parseChunkChecksum(chunkChecksumStr); int chunkSize = Integer.parseInt(attributes.getValue("size")); ChunkEntry chunkEntry = new ChunkEntry(chunkChecksum, chunkSize); databaseVersion.addChunk(chunkEntry); } else if (elementPath .equalsIgnoreCase("/database/databaseVersions/databaseVersion/fileContents/fileContent")) { String checksumStr = attributes.getValue("checksum"); long size = Long.parseLong(attributes.getValue("size")); fileContent = new FileContent(); fileContent.setChecksum(FileChecksum.parseFileChecksum(checksumStr)); fileContent.setSize(size); } else if (elementPath.equalsIgnoreCase( "/database/databaseVersions/databaseVersion/fileContents/fileContent/chunkRefs/chunkRef")) { String chunkChecksumStr = attributes.getValue("ref"); fileContent.addChunk(ChunkChecksum.parseChunkChecksum(chunkChecksumStr)); } else if (elementPath .equalsIgnoreCase("/database/databaseVersions/databaseVersion/multiChunks/multiChunk")) { String multChunkIdStr = attributes.getValue("id"); MultiChunkId multiChunkId = MultiChunkId.parseMultiChunkId(multChunkIdStr); long size = Long.parseLong(attributes.getValue("size")); if (multiChunkId == null) { throw new SAXException("Cannot read ID from multichunk " + multChunkIdStr); } multiChunk = new MultiChunkEntry(multiChunkId, size); } else if (elementPath.equalsIgnoreCase( "/database/databaseVersions/databaseVersion/multiChunks/multiChunk/chunkRefs/chunkRef")) { String chunkChecksumStr = attributes.getValue("ref"); multiChunk.addChunk(ChunkChecksum.parseChunkChecksum(chunkChecksumStr)); } else if (elementPath .equalsIgnoreCase("/database/databaseVersions/databaseVersion/fileHistories/fileHistory")) { String fileHistoryIdStr = attributes.getValue("id"); FileHistoryId fileId = FileHistoryId.parseFileId(fileHistoryIdStr); fileHistory = new PartialFileHistory(fileId); } else if (elementPath.equalsIgnoreCase( "/database/databaseVersions/databaseVersion/fileHistories/fileHistory/fileVersions/fileVersion")) { String fileVersionStr = attributes.getValue("version"); String path = attributes.getValue("path"); String pathEncoded = attributes.getValue("pathEncoded"); String sizeStr = attributes.getValue("size"); String typeStr = attributes.getValue("type"); String statusStr = attributes.getValue("status"); String lastModifiedStr = attributes.getValue("lastModified"); String updatedStr = attributes.getValue("updated"); String checksumStr = attributes.getValue("checksum"); String linkTarget = attributes.getValue("linkTarget"); String dosAttributes = attributes.getValue("dosattrs"); String posixPermissions = attributes.getValue("posixperms"); if (fileVersionStr == null || (path == null && pathEncoded == null) || typeStr == null || statusStr == null || sizeStr == null || lastModifiedStr == null) { throw new SAXException( "FileVersion: Attributes missing: version, path/pathEncoded, type, status, size and last modified are mandatory"); } // Filter it if it was purged somewhere in the future, see #58 Long fileVersionNum = Long.parseLong(fileVersionStr); // Go add it! FileVersion fileVersion = new FileVersion(); fileVersion.setVersion(fileVersionNum); if (path != null) { fileVersion.setPath(path); } else { try { fileVersion.setPath(new String(Base64.decodeBase64(pathEncoded), "UTF-8")); } catch (UnsupportedEncodingException e) { throw new RuntimeException("Invalid Base64 encoding for filename: " + pathEncoded); } } fileVersion.setType(FileType.valueOf(typeStr)); fileVersion.setStatus(FileStatus.valueOf(statusStr)); fileVersion.setSize(Long.parseLong(sizeStr)); fileVersion.setLastModified(new Date(Long.parseLong(lastModifiedStr))); if (updatedStr != null) { fileVersion.setUpdated(new Date(Long.parseLong(updatedStr))); } if (checksumStr != null) { fileVersion.setChecksum(FileChecksum.parseFileChecksum(checksumStr)); } if (linkTarget != null) { fileVersion.setLinkTarget(linkTarget); } if (dosAttributes != null) { fileVersion.setDosAttributes(dosAttributes); } if (posixPermissions != null) { fileVersion.setPosixPermissions(posixPermissions); } fileHistory.addFileVersion(fileVersion); } } } @Override public void endElement(String uri, String localName, String qName) throws SAXException { if (elementPath.equalsIgnoreCase("/database/databaseVersions/databaseVersion")) { if (vectorClockInLoadRange) { database.addDatabaseVersion(databaseVersion); logger.log(Level.INFO, " + Added database version " + databaseVersion.getHeader()); } else { //logger.log(Level.FINEST, " + IGNORING database version " + databaseVersion.getHeader() + " (not in load range " + versionFrom + " - " // + versionTo + " OR type filter mismatch: " + filterType + " =?= " + databaseVersion.getHeader().getType()); } databaseVersion = null; vectorClockInLoadRange = true; } else if (elementPath.equalsIgnoreCase("/database/databaseVersions/databaseVersion/header/vectorClock")) { vectorClockInLoadRange = vectorClockInRange(vectorClock, versionFrom, versionTo); databaseVersion.setVectorClock(vectorClock); vectorClock = null; } else if (readType == DatabaseReadType.FULL) { if (elementPath .equalsIgnoreCase("/database/databaseVersions/databaseVersion/fileContents/fileContent")) { databaseVersion.addFileContent(fileContent); fileContent = null; } else if (elementPath .equalsIgnoreCase("/database/databaseVersions/databaseVersion/multiChunks/multiChunk")) { databaseVersion.addMultiChunk(multiChunk); multiChunk = null; } else if (elementPath .equalsIgnoreCase("/database/databaseVersions/databaseVersion/fileHistories/fileHistory")) { // File history might be empty if file versions are ignored! if (fileHistory.getFileVersions().size() > 0) { databaseVersion.addFileHistory(fileHistory); } fileHistory = null; } else { // System.out.println("NO MATCH"); } } elementPath = elementPath.substring(0, elementPath.lastIndexOf("/")); } @Override public void characters(char[] ch, int start, int length) throws SAXException { // Nothing } private boolean vectorClockInRange(VectorClock vectorClock, VectorClock vectorClockRangeFrom, VectorClock vectorClockRangeTo) { // Determine if: versionFrom < databaseVersion boolean greaterOrEqualToVersionFrom = false; if (vectorClockRangeFrom == null) { greaterOrEqualToVersionFrom = true; } else { VectorClockComparison comparison = VectorClock.compare(vectorClockRangeFrom, vectorClock); if (comparison == VectorClockComparison.EQUAL || comparison == VectorClockComparison.SMALLER) { greaterOrEqualToVersionFrom = true; } } // Determine if: databaseVersion < versionTo boolean lowerOrEqualToVersionTo = false; if (vectorClockRangeTo == null) { lowerOrEqualToVersionTo = true; } else { VectorClockComparison comparison = VectorClock.compare(vectorClock, vectorClockRangeTo); if (comparison == VectorClockComparison.EQUAL || comparison == VectorClockComparison.SMALLER) { lowerOrEqualToVersionTo = true; } } return greaterOrEqualToVersionFrom && lowerOrEqualToVersionTo; } }