Java tutorial
/******************************************************************************* * Copyright (c) 2004, 2008 IBM Corporation and others. * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Public License v1.0 * which accompanies this distribution, and is available at * http://www.eclipse.org/legal/epl-v10.html * * Contributors: * IBM Corporation - initial API and implementation * Red Hat, Inc - added bzip2 support * Remy Chi Jian Suen <remy.suen@gmail.com> - Bug 243347 TarFile should not throw NPE in finalize() *******************************************************************************/ package org.eclipse.ui.internal.wizards.datatransfer; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; import java.util.Enumeration; import java.util.zip.GZIPInputStream; import org.apache.commons.compress.compressors.bzip2.BZip2CompressorInputStream; import org.tukaani.xz.XZInputStream; /** * Reads a .tar or .tar.gz archive file, providing an index enumeration * and allows for accessing an InputStream for arbitrary files in the * archive. * * @since 3.1 */ public class TarFile { private File file; private TarInputStream entryEnumerationStream; private TarEntry curEntry; private TarInputStream entryStream; private InputStream internalEntryStream; /** * Create a new TarFile for the given file. * * @param file * @throws TarException * @throws IOException */ public TarFile(File file) throws TarException, IOException { this.file = file; InputStream in = new FileInputStream(file); //boolean flag to signify whether continue testing file type or not boolean fileTypeIdentified = false; // First, check if it's a GZIPInputStream. try { in = new GZIPInputStream(in); fileTypeIdentified = true; } catch (IOException e) { //If it is not compressed we close //the old one and recreate in.close(); in = new FileInputStream(file); } // try bzip2, if it still fails, try other formats. if (!fileTypeIdentified) { try { in = new BZip2CompressorInputStream(in); fileTypeIdentified = true; } catch (IOException e) { // If it is not compressed we close // the old one and recreate in.close(); in = new FileInputStream(file); } } //additional format can be added here in a similar fashion as the previous if statement block. // try xz, if it still fails, treat it as a simple uncompressed tar. if (!fileTypeIdentified) { try { in = new XZInputStream(in); fileTypeIdentified = true; } catch (IOException e) { // If it is not compressed we close // the old one and recreate in.close(); in = new FileInputStream(file); } } //create TarInputStream try { entryEnumerationStream = new TarInputStream(in); } catch (TarException ex) { in.close(); throw ex; } curEntry = entryEnumerationStream.getNextEntry(); } /** * Close the tar file input stream. * * @throws IOException if the file cannot be successfully closed */ public void close() throws IOException { if (entryEnumerationStream != null) entryEnumerationStream.close(); if (internalEntryStream != null) internalEntryStream.close(); } /** * Create a new TarFile for the given path name. * * @param filename * @throws TarException * @throws IOException */ public TarFile(String filename) throws TarException, IOException { this(new File(filename)); } /** * Returns an enumeration cataloguing the tar archive. * * @return enumeration of all files in the archive */ public Enumeration entries() { return new Enumeration() { public boolean hasMoreElements() { return (curEntry != null); } public Object nextElement() { TarEntry oldEntry = curEntry; try { curEntry = entryEnumerationStream.getNextEntry(); } catch (TarException e) { curEntry = null; } catch (IOException e) { curEntry = null; } return oldEntry; } }; } /** * Returns a new InputStream for the given file in the tar archive. * * @param entry * @return an input stream for the given file * @throws TarException * @throws IOException */ public InputStream getInputStream(TarEntry entry) throws TarException, IOException { if (entryStream == null || !entryStream.skipToEntry(entry)) { if (internalEntryStream != null) { internalEntryStream.close(); } internalEntryStream = new FileInputStream(file); boolean fileFormatIdentified = false; // First, check if it's a GZIPInputStream. try { internalEntryStream = new GZIPInputStream(internalEntryStream); fileFormatIdentified = true; } catch (IOException e) { //If it is not compressed we close //the old one and recreate internalEntryStream.close(); internalEntryStream = new FileInputStream(file); } // try bzip2, if it still fails, try other formats. if (!fileFormatIdentified) { try { internalEntryStream = new BZip2CompressorInputStream(internalEntryStream); fileFormatIdentified = true; } catch (IOException e) { // If it is not compressed we close // the old one and recreate internalEntryStream.close(); internalEntryStream = new FileInputStream(file); } } // new format can be added here in a similar fashion as the previous if statement block. // try xz, if it still fails, treat it as a simple uncompressed tar file. if (!fileFormatIdentified) { try { internalEntryStream = new XZInputStream(internalEntryStream); fileFormatIdentified = true; } catch (IOException e) { // If it is not compressed we close // the old one and recreate internalEntryStream.close(); internalEntryStream = new FileInputStream(file); } } //create TarInputStream entryStream = new TarInputStream(internalEntryStream, entry) { public void close() { // Ignore close() since we want to reuse the stream. } }; } return entryStream; } /** * Returns the path name of the file this archive represents. * * @return path */ public String getName() { return file.getPath(); } /* (non-Javadoc) * @see java.util.zip.ZipFile#finalize() * */ protected void finalize() throws Throwable { close(); } }