Java tutorial
/* * * This file is part of the iText (R) project. Copyright (c) 1998-2019 iText Group NV * Authors: Bruno Lowagie, Paulo Soares, 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 Public License for more details. * You should have received a copy of the GNU Affero General Public 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 Public License. * * In accordance with Section 7(b) of the GNU Affero General Public 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.pdf; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.util.zip.Deflater; import java.util.zip.DeflaterOutputStream; import com.itextpdf.text.error_messages.MessageLocalization; import com.itextpdf.text.DocWriter; import com.itextpdf.text.Document; import com.itextpdf.text.ExceptionConverter; import com.itextpdf.text.pdf.internal.PdfIsoKeys; /** * <CODE>PdfStream</CODE> is the Pdf stream object. * <P> * A stream, like a string, is a sequence of characters. However, an application can * read a small portion of a stream at a time, while a string must be read in its entirety. * For this reason, objects with potentially large amounts of data, such as images and * page descriptions, are represented as streams.<BR> * A stream consists of a dictionary that describes a sequence of characters, followed by * the keyword <B>stream</B>, followed by zero or more lines of characters, followed by * the keyword <B>endstream</B>.<BR> * All streams must be <CODE>PdfIndirectObject</CODE>s. The stream dictionary must be a direct * object. The keyword <B>stream</B> that follows the stream dictionary should be followed by * a carriage return and linefeed or just a linefeed.<BR> * Remark: In this version only the FLATEDECODE-filter is supported.<BR> * This object is described in the 'Portable Document Format Reference Manual version 1.7' * section 3.2.7 (page 60-63).<BR> * * @see PdfObject * @see PdfDictionary */ public class PdfStream extends PdfDictionary { // membervariables /** * A possible compression level. * @since 2.1.3 */ public static final int DEFAULT_COMPRESSION = -1; /** * A possible compression level. * @since 2.1.3 */ public static final int NO_COMPRESSION = 0; /** * A possible compression level. * @since 2.1.3 */ public static final int BEST_SPEED = 1; /** * A possible compression level. * @since 2.1.3 */ public static final int BEST_COMPRESSION = 9; /** is the stream compressed? */ protected boolean compressed = false; /** * The level of compression. * @since 2.1.3 */ protected int compressionLevel = NO_COMPRESSION; protected ByteArrayOutputStream streamBytes = null; protected InputStream inputStream; protected PdfIndirectReference ref; protected int inputStreamLength = -1; protected PdfWriter writer; protected int rawLength; static final byte STARTSTREAM[] = DocWriter.getISOBytes("stream\n"); static final byte ENDSTREAM[] = DocWriter.getISOBytes("\nendstream"); static final int SIZESTREAM = STARTSTREAM.length + ENDSTREAM.length; // constructors /** * Constructs a <CODE>PdfStream</CODE>-object. * * @param bytes content of the new <CODE>PdfObject</CODE> as an array of <CODE>byte</CODE>. */ public PdfStream(byte[] bytes) { super(); type = STREAM; this.bytes = bytes; rawLength = bytes.length; put(PdfName.LENGTH, new PdfNumber(bytes.length)); } /** * Creates an efficient stream. No temporary array is ever created. The <CODE>InputStream</CODE> * is totally consumed but is not closed. The general usage is: * <p> * <pre> * InputStream in = ...; * PdfStream stream = new PdfStream(in, writer); * stream.flateCompress(); * writer.addToBody(stream); * stream.writeLength(); * in.close(); * </pre> * @param inputStream the data to write to this stream * @param writer the <CODE>PdfWriter</CODE> for this stream */ public PdfStream(InputStream inputStream, PdfWriter writer) { super(); type = STREAM; this.inputStream = inputStream; this.writer = writer; ref = writer.getPdfIndirectReference(); put(PdfName.LENGTH, ref); } /** * Constructs a <CODE>PdfStream</CODE>-object. */ protected PdfStream() { super(); type = STREAM; } /** * Writes the stream length to the <CODE>PdfWriter</CODE>. * <p> * This method must be called and can only be called if the constructor {@link #PdfStream(InputStream,PdfWriter)} * is used to create the stream. * @throws IOException on error * @see #PdfStream(InputStream,PdfWriter) */ public void writeLength() throws IOException { if (inputStream == null) throw new UnsupportedOperationException(MessageLocalization.getComposedMessage( "writelength.can.only.be.called.in.a.contructed.pdfstream.inputstream.pdfwriter")); if (inputStreamLength == -1) throw new IOException(MessageLocalization .getComposedMessage("writelength.can.only.be.called.after.output.of.the.stream.body")); writer.addToBody(new PdfNumber(inputStreamLength), ref, false); } /** * Gets the raw length of the stream. * @return the raw length of the stream */ public int getRawLength() { return rawLength; } /** * Compresses the stream. */ public void flateCompress() { flateCompress(DEFAULT_COMPRESSION); } /** * Compresses the stream. * @param compressionLevel the compression level (0 = best speed, 9 = best compression, -1 is default) * @since 2.1.3 */ public void flateCompress(int compressionLevel) { if (!Document.compress) return; // check if the flateCompress-method has already been if (compressed) { return; } this.compressionLevel = compressionLevel; if (inputStream != null) { compressed = true; return; } // check if a filter already exists PdfObject filter = PdfReader.getPdfObject(get(PdfName.FILTER)); if (filter != null) { if (filter.isName()) { if (PdfName.FLATEDECODE.equals(filter)) return; } else if (filter.isArray()) { if (((PdfArray) filter).contains(PdfName.FLATEDECODE)) return; } else { throw new RuntimeException(MessageLocalization .getComposedMessage("stream.could.not.be.compressed.filter.is.not.a.name.or.array")); } } try { // compress ByteArrayOutputStream stream = new ByteArrayOutputStream(); Deflater deflater = new Deflater(compressionLevel); DeflaterOutputStream zip = new DeflaterOutputStream(stream, deflater); if (streamBytes != null) streamBytes.writeTo(zip); else zip.write(bytes); zip.close(); deflater.end(); // update the object streamBytes = stream; bytes = null; put(PdfName.LENGTH, new PdfNumber(streamBytes.size())); if (filter == null) { put(PdfName.FILTER, PdfName.FLATEDECODE); } else { PdfArray filters = new PdfArray(filter); filters.add(0, PdfName.FLATEDECODE); put(PdfName.FILTER, filters); } compressed = true; } catch (IOException ioe) { throw new ExceptionConverter(ioe); } } // public int getStreamLength(PdfWriter writer) { // if (dicBytes == null) // toPdf(writer); // if (streamBytes != null) // return streamBytes.size() + dicBytes.length + SIZESTREAM; // else // return bytes.length + dicBytes.length + SIZESTREAM; // } protected void superToPdf(PdfWriter writer, OutputStream os) throws IOException { super.toPdf(writer, os); } /** * @see com.itextpdf.text.pdf.PdfDictionary#toPdf(com.itextpdf.text.pdf.PdfWriter, java.io.OutputStream) */ public void toPdf(PdfWriter writer, OutputStream os) throws IOException { if (inputStream != null && compressed) put(PdfName.FILTER, PdfName.FLATEDECODE); PdfEncryption crypto = null; if (writer != null) crypto = writer.getEncryption(); if (crypto != null) { PdfObject filter = get(PdfName.FILTER); if (filter != null) { if (PdfName.CRYPT.equals(filter)) crypto = null; else if (filter.isArray()) { PdfArray a = (PdfArray) filter; if (!a.isEmpty() && PdfName.CRYPT.equals(a.getPdfObject(0))) crypto = null; } } } PdfObject nn = get(PdfName.LENGTH); if (crypto != null && nn != null && nn.isNumber()) { int sz = ((PdfNumber) nn).intValue(); put(PdfName.LENGTH, new PdfNumber(crypto.calculateStreamSize(sz))); superToPdf(writer, os); put(PdfName.LENGTH, nn); } else superToPdf(writer, os); PdfWriter.checkPdfIsoConformance(writer, PdfIsoKeys.PDFISOKEY_STREAM, this); os.write(STARTSTREAM); if (inputStream != null) { rawLength = 0; DeflaterOutputStream def = null; OutputStreamCounter osc = new OutputStreamCounter(os); OutputStreamEncryption ose = null; OutputStream fout = osc; if (crypto != null && !crypto.isEmbeddedFilesOnly()) fout = ose = crypto.getEncryptionStream(fout); Deflater deflater = null; if (compressed) { deflater = new Deflater(compressionLevel); fout = def = new DeflaterOutputStream(fout, deflater, 0x8000); } byte buf[] = new byte[4192]; while (true) { int n = inputStream.read(buf); if (n <= 0) break; fout.write(buf, 0, n); rawLength += n; } if (def != null) { def.finish(); deflater.end(); } if (ose != null) ose.finish(); inputStreamLength = (int) osc.getCounter(); } else { if (crypto != null && !crypto.isEmbeddedFilesOnly()) { byte b[]; if (streamBytes != null) { b = crypto.encryptByteArray(streamBytes.toByteArray()); } else { b = crypto.encryptByteArray(bytes); } os.write(b); } else { if (streamBytes != null) streamBytes.writeTo(os); else os.write(bytes); } } os.write(ENDSTREAM); } /** * Writes the data content to an <CODE>OutputStream</CODE>. * @param os the destination to write to * @throws IOException on error */ public void writeContent(OutputStream os) throws IOException { if (streamBytes != null) streamBytes.writeTo(os); else if (bytes != null) os.write(bytes); } /** * @see com.itextpdf.text.pdf.PdfObject#toString() */ public String toString() { if (get(PdfName.TYPE) == null) return "Stream"; return "Stream of type: " + get(PdfName.TYPE); } }