001 /*
002 * Copyright 1997-2006 Sun Microsystems, Inc. All Rights Reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation. Sun designates this
008 * particular file as subject to the "Classpath" exception as provided
009 * by Sun in the LICENSE file that accompanied this code.
010 *
011 * This code is distributed in the hope that it will be useful, but WITHOUT
012 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014 * version 2 for more details (a copy is included in the LICENSE file that
015 * accompanied this code).
016 *
017 * You should have received a copy of the GNU General Public License version
018 * 2 along with this work; if not, write to the Free Software Foundation,
019 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020 *
021 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022 * CA 95054 USA or visit www.sun.com if you need additional information or
023 * have any questions.
024 */
025
026 package java.util.jar;
027
028 import java.util.zip.*;
029 import java.io.*;
030
031 /**
032 * The <code>JarOutputStream</code> class is used to write the contents
033 * of a JAR file to any output stream. It extends the class
034 * <code>java.util.zip.ZipOutputStream</code> with support
035 * for writing an optional <code>Manifest</code> entry. The
036 * <code>Manifest</code> can be used to specify meta-information about
037 * the JAR file and its entries.
038 *
039 * @author David Connelly
040 * @version 1.30, 05/05/07
041 * @see Manifest
042 * @see java.util.zip.ZipOutputStream
043 * @since 1.2
044 */
045 public class JarOutputStream extends ZipOutputStream {
046 private static final int JAR_MAGIC = 0xCAFE;
047
048 /**
049 * Creates a new <code>JarOutputStream</code> with the specified
050 * <code>Manifest</code>. The manifest is written as the first
051 * entry to the output stream.
052 *
053 * @param out the actual output stream
054 * @param man the optional <code>Manifest</code>
055 * @exception IOException if an I/O error has occurred
056 */
057 public JarOutputStream(OutputStream out, Manifest man)
058 throws IOException {
059 super (out);
060 if (man == null) {
061 throw new NullPointerException("man");
062 }
063 ZipEntry e = new ZipEntry(JarFile.MANIFEST_NAME);
064 putNextEntry(e);
065 man.write(new BufferedOutputStream(this ));
066 closeEntry();
067 }
068
069 /**
070 * Creates a new <code>JarOutputStream</code> with no manifest.
071 * @param out the actual output stream
072 * @exception IOException if an I/O error has occurred
073 */
074 public JarOutputStream(OutputStream out) throws IOException {
075 super (out);
076 }
077
078 /**
079 * Begins writing a new JAR file entry and positions the stream
080 * to the start of the entry data. This method will also close
081 * any previous entry. The default compression method will be
082 * used if no compression method was specified for the entry.
083 * The current time will be used if the entry has no set modification
084 * time.
085 *
086 * @param ze the ZIP/JAR entry to be written
087 * @exception ZipException if a ZIP error has occurred
088 * @exception IOException if an I/O error has occurred
089 */
090 public void putNextEntry(ZipEntry ze) throws IOException {
091 if (firstEntry) {
092 // Make sure that extra field data for first JAR
093 // entry includes JAR magic number id.
094 byte[] edata = ze.getExtra();
095 if (edata == null || !hasMagic(edata)) {
096 if (edata == null) {
097 edata = new byte[4];
098 } else {
099 // Prepend magic to existing extra data
100 byte[] tmp = new byte[edata.length + 4];
101 System.arraycopy(edata, 0, tmp, 4, edata.length);
102 edata = tmp;
103 }
104 set16(edata, 0, JAR_MAGIC); // extra field id
105 set16(edata, 2, 0); // extra field size
106 ze.setExtra(edata);
107 }
108 firstEntry = false;
109 }
110 super .putNextEntry(ze);
111 }
112
113 private boolean firstEntry = true;
114
115 /*
116 * Returns true if specified byte array contains the
117 * jar magic extra field id.
118 */
119 private static boolean hasMagic(byte[] edata) {
120 try {
121 int i = 0;
122 while (i < edata.length) {
123 if (get16(edata, i) == JAR_MAGIC) {
124 return true;
125 }
126 i += get16(edata, i + 2) + 4;
127 }
128 } catch (ArrayIndexOutOfBoundsException e) {
129 // Invalid extra field data
130 }
131 return false;
132 }
133
134 /*
135 * Fetches unsigned 16-bit value from byte array at specified offset.
136 * The bytes are assumed to be in Intel (little-endian) byte order.
137 */
138 private static int get16(byte[] b, int off) {
139 return (b[off] & 0xff) | ((b[off + 1] & 0xff) << 8);
140 }
141
142 /*
143 * Sets 16-bit value at specified offset. The bytes are assumed to
144 * be in Intel (little-endian) byte order.
145 */
146 private static void set16(byte[] b, int off, int value) {
147 b[off + 0] = (byte) value;
148 b[off + 1] = (byte) (value >> 8);
149 }
150 }
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