1 /*
2 * Copyright 1997-2006 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26 package java.util.jar;
27
28 import java.util.zip;
29 import java.io;
30
31 /**
32 * The <code>JarOutputStream</code> class is used to write the contents
33 * of a JAR file to any output stream. It extends the class
34 * <code>java.util.zip.ZipOutputStream</code> with support
35 * for writing an optional <code>Manifest</code> entry. The
36 * <code>Manifest</code> can be used to specify meta-information about
37 * the JAR file and its entries.
38 *
39 * @author David Connelly
40 * @see Manifest
41 * @see java.util.zip.ZipOutputStream
42 * @since 1.2
43 */
44 public
45 class JarOutputStream extends ZipOutputStream {
46 private static final int JAR_MAGIC = 0xCAFE;
47
48 /**
49 * Creates a new <code>JarOutputStream</code> with the specified
50 * <code>Manifest</code>. The manifest is written as the first
51 * entry to the output stream.
52 *
53 * @param out the actual output stream
54 * @param man the optional <code>Manifest</code>
55 * @exception IOException if an I/O error has occurred
56 */
57 public JarOutputStream(OutputStream out, Manifest man) throws IOException {
58 super(out);
59 if (man == null) {
60 throw new NullPointerException("man");
61 }
62 ZipEntry e = new ZipEntry(JarFile.MANIFEST_NAME);
63 putNextEntry(e);
64 man.write(new BufferedOutputStream(this));
65 closeEntry();
66 }
67
68 /**
69 * Creates a new <code>JarOutputStream</code> with no manifest.
70 * @param out the actual output stream
71 * @exception IOException if an I/O error has occurred
72 */
73 public JarOutputStream(OutputStream out) throws IOException {
74 super(out);
75 }
76
77 /**
78 * Begins writing a new JAR file entry and positions the stream
79 * to the start of the entry data. This method will also close
80 * any previous entry. The default compression method will be
81 * used if no compression method was specified for the entry.
82 * The current time will be used if the entry has no set modification
83 * time.
84 *
85 * @param ze the ZIP/JAR entry to be written
86 * @exception ZipException if a ZIP error has occurred
87 * @exception IOException if an I/O error has occurred
88 */
89 public void putNextEntry(ZipEntry ze) throws IOException {
90 if (firstEntry) {
91 // Make sure that extra field data for first JAR
92 // entry includes JAR magic number id.
93 byte[] edata = ze.getExtra();
94 if (edata == null || !hasMagic(edata)) {
95 if (edata == null) {
96 edata = new byte[4];
97 } else {
98 // Prepend magic to existing extra data
99 byte[] tmp = new byte[edata.length + 4];
100 System.arraycopy(edata, 0, tmp, 4, edata.length);
101 edata = tmp;
102 }
103 set16(edata, 0, JAR_MAGIC); // extra field id
104 set16(edata, 2, 0); // extra field size
105 ze.setExtra(edata);
106 }
107 firstEntry = false;
108 }
109 super.putNextEntry(ze);
110 }
111
112 private boolean firstEntry = true;
113
114 /*
115 * Returns true if specified byte array contains the
116 * jar magic extra field id.
117 */
118 private static boolean hasMagic(byte[] edata) {
119 try {
120 int i = 0;
121 while (i < edata.length) {
122 if (get16(edata, i) == JAR_MAGIC) {
123 return true;
124 }
125 i += get16(edata, i + 2) + 4;
126 }
127 } catch (ArrayIndexOutOfBoundsException e) {
128 // Invalid extra field data
129 }
130 return false;
131 }
132
133 /*
134 * Fetches unsigned 16-bit value from byte array at specified offset.
135 * The bytes are assumed to be in Intel (little-endian) byte order.
136 */
137 private static int get16(byte[] b, int off) {
138 return (b[off] & 0xff) | ((b[off+1] & 0xff) << 8);
139 }
140
141 /*
142 * Sets 16-bit value at specified offset. The bytes are assumed to
143 * be in Intel (little-endian) byte order.
144 */
145 private static void set16(byte[] b, int off, int value) {
146 b[off+0] = (byte)value;
147 b[off+1] = (byte)(value >> 8);
148 }
149 }
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