Java tutorial
/* * * This file is part of the iText (R) project. Copyright (c) 1998-2019 iText Group NV * Authors: Kevin Day, Bruno Lowagie, et al. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU Affero General Public License version 3 * as published by the Free Software Foundation with the addition of the * following permission added to Section 15 as permitted in Section 7(a): * FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY * ITEXT GROUP. ITEXT GROUP DISCLAIMS THE WARRANTY OF NON INFRINGEMENT * OF THIRD PARTY RIGHTS. * * 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 Affero General License for more * details. You should have received a copy of the GNU Affero General License * along with this program; if not, see http://www.gnu.org/licenses or write to * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, * MA, 02110-1301 USA, or download the license from the following URL: * http://itextpdf.com/terms-of-use/ * * The interactive user interfaces in modified source and object code versions * of this program must display Appropriate Legal Notices, as required under * Section 5 of the GNU Affero General License. * * In accordance with Section 7(b) of the GNU Affero General License, a covered * work must retain the producer line in every PDF that is created or * manipulated using iText. * * You can be released from the requirements of the license by purchasing a * commercial license. Buying such a license is mandatory as soon as you develop * commercial activities involving the iText software without disclosing the * source code of your own applications. These activities include: offering paid * services to customers as an ASP, serving PDFs on the fly in a web * application, shipping iText with a closed source product. * * For more information, please contact iText Software Corp. at this address: * sales@itextpdf.com */ package com.itextpdf.text.io; import com.itextpdf.text.error_messages.MessageLocalization; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; import java.io.RandomAccessFile; import java.net.URL; import java.nio.channels.FileChannel; /** * Factory to create {@link RandomAccessSource} objects based on various types of sources * @since 5.3.5 * */ public final class RandomAccessSourceFactory { /** * whether the full content of the source should be read into memory at construction */ private boolean forceRead = false; /** * Whether {@link RandomAccessFile} should be used instead of a {@link FileChannel}, where applicable */ private boolean usePlainRandomAccess = false; /** * Whether the underlying file should have a RW lock on it or just an R lock */ private boolean exclusivelyLockFile = false; /** * Creates a factory that will give preference to accessing the underling data source using memory mapped files */ public RandomAccessSourceFactory() { } /** * Determines whether the full content of the source will be read into memory * @param forceRead true if the full content will be read, false otherwise * @return this object (this allows chaining of method calls) */ public RandomAccessSourceFactory setForceRead(boolean forceRead) { this.forceRead = forceRead; return this; } /** * Determines whether {@link RandomAccessFile} should be used as the primary data access mechanism * @param usePlainRandomAccess whether {@link RandomAccessFile} should be used as the primary data access mechanism * @return this object (this allows chaining of method calls) */ public RandomAccessSourceFactory setUsePlainRandomAccess(boolean usePlainRandomAccess) { this.usePlainRandomAccess = usePlainRandomAccess; return this; } public RandomAccessSourceFactory setExclusivelyLockFile(boolean exclusivelyLockFile) { this.exclusivelyLockFile = exclusivelyLockFile; return this; } /** * Creates a {@link RandomAccessSource} based on a byte array * @param data the byte array * @return the newly created {@link RandomAccessSource} */ public RandomAccessSource createSource(byte[] data) { return new ArrayRandomAccessSource(data); } public RandomAccessSource createSource(RandomAccessFile raf) throws IOException { return new RAFRandomAccessSource(raf); } /** * Creates a {@link RandomAccessSource} based on a URL. The data available at the URL is read into memory and used * as the source for the {@link RandomAccessSource} * @param url the url to read from * @return the newly created {@link RandomAccessSource} */ public RandomAccessSource createSource(URL url) throws IOException { InputStream is = url.openStream(); try { return createSource(is); } finally { try { is.close(); } catch (IOException ioe) { } } } /** * Creates a {@link RandomAccessSource} based on an {@link InputStream}. The full content of the InputStream is read into memory and used * as the source for the {@link RandomAccessSource} * @param is the stream to read from * @return the newly created {@link RandomAccessSource} */ public RandomAccessSource createSource(InputStream is) throws IOException { try { return createSource(StreamUtil.inputStreamToArray(is)); } finally { try { is.close(); } catch (IOException ioe) { } } } /** * Creates a {@link RandomAccessSource} based on a filename string. * If the filename describes a URL, a URL based source is created * If the filename describes a file on disk, the contents may be read into memory (if forceRead is true), opened using memory mapped file channel (if usePlainRandomAccess is false), or opened using {@link RandomAccessFile} access (if usePlainRandomAccess is true) * This call will automatically failover to using {@link RandomAccessFile} if the memory map operation fails * @param filename the name of the file or resource to create the {@link RandomAccessSource} for * @return the newly created {@link RandomAccessSource} */ public RandomAccessSource createBestSource(String filename) throws IOException { File file = new File(filename); if (!file.canRead()) { if (filename.startsWith("file:/") || filename.startsWith("http://") || filename.startsWith("https://") || filename.startsWith("jar:") || filename.startsWith("wsjar:") || filename.startsWith("wsjar:") || filename.startsWith("vfszip:")) { return createSource(new URL(filename)); } else { return createByReadingToMemory(filename); } } if (forceRead) { return createByReadingToMemory(new FileInputStream(filename)); } String openMode = exclusivelyLockFile ? "rw" : "r"; RandomAccessFile raf = new RandomAccessFile(file, openMode); if (exclusivelyLockFile) { raf.getChannel().lock(); } try { // ownership of the RAF passes to whatever source is created by createBestSource. return createBestSource(raf); } catch (IOException e) { // If creation of the source throws, we must close the RAF we created. try { raf.close(); } catch (IOException ignore) { } throw e; } catch (RuntimeException e) { // if we get a runtime exception during opening, we must close the RAF we created try { raf.close(); } catch (IOException ignore) { } throw e; } } /** * Creates a {@link RandomAccessSource} based on a RandomAccessFile. * The source will be opened using memory mapped file channel (if usePlainRandomAccess is false), or opened using {@link RandomAccessFile} access (if usePlainRandomAccess is true) * This call will automatically failover to using {@link RandomAccessFile} if the memory map operation fails * If the source couldn't be opened, the RandomAccessFile will be closed * @param raf the RandomAccessFile to create a {@link RandomAccessSource} for * @return the newly created {@link RandomAccessSource} */ public RandomAccessSource createBestSource(RandomAccessFile raf) throws IOException { if (usePlainRandomAccess) { return new RAFRandomAccessSource(raf); } if (raf.length() <= 0) // files with zero length can't be mapped and will throw an IllegalArgumentException. Just open using a simple RAF source. return new RAFRandomAccessSource(raf); try { // ownership of the RAF passes to whatever source is created by createBestSource. return createBestSource(raf.getChannel()); } catch (MapFailedException e) { return new RAFRandomAccessSource(raf); } } /** * Creates a {@link RandomAccessSource} based on memory mapping a file channel. * Unless you are explicitly working with a FileChannel already, it is better to use * {@link RandomAccessSourceFactory#createBestSource(String)}. * If the file is large, it will be opened using a paging strategy. * @param filename the name of the file or resource to create the {@link RandomAccessSource} for * @return the newly created {@link RandomAccessSource} */ public RandomAccessSource createBestSource(FileChannel channel) throws IOException { if (channel.size() <= PagedChannelRandomAccessSource.DEFAULT_TOTAL_BUFSIZE) { // if less than the fully mapped usage of PagedFileChannelRandomAccessSource, just map the whole thing and be done with it return new GetBufferedRandomAccessSource(new FileChannelRandomAccessSource(channel)); } else { return new GetBufferedRandomAccessSource(new PagedChannelRandomAccessSource(channel)); } } public RandomAccessSource createRanged(RandomAccessSource source, long[] ranges) throws IOException { RandomAccessSource[] sources = new RandomAccessSource[ranges.length / 2]; for (int i = 0; i < ranges.length; i += 2) { sources[i / 2] = new WindowRandomAccessSource(source, ranges[i], ranges[i + 1]); } return new GroupedRandomAccessSource(sources); } /** * Creates a new {@link RandomAccessSource} by reading the specified file/resource into memory * @param filename the name of the resource to read * @return the newly created {@link RandomAccessSource} * @throws IOException if reading the underling file or stream fails */ private RandomAccessSource createByReadingToMemory(String filename) throws IOException { InputStream is = StreamUtil.getResourceStream(filename); if (is == null) throw new IOException( MessageLocalization.getComposedMessage("1.not.found.as.file.or.resource", filename)); return createByReadingToMemory(is); } /** * Creates a new {@link RandomAccessSource} by reading the specified file/resource into memory * @param is the name of the resource to read * @return the newly created {@link RandomAccessSource} * @throws IOException if reading the underling file or stream fails */ private RandomAccessSource createByReadingToMemory(InputStream is) throws IOException { try { return new ArrayRandomAccessSource(StreamUtil.inputStreamToArray(is)); } finally { try { is.close(); } catch (IOException ioe) { } } } }