1 /*
2 * Copyright 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.zip;
27
28 import java.io.FilterInputStream;
29 import java.io.InputStream;
30 import java.io.IOException;
31
32 /**
33 * Implements an input stream filter for compressing data in the "deflate"
34 * compression format.
35 *
36 * @since 1.6
37 * @author David R Tribble (david@tribble.com)
38 *
39 * @see DeflaterOutputStream
40 * @see InflaterOutputStream
41 * @see InflaterInputStream
42 */
43
44 public class DeflaterInputStream extends FilterInputStream {
45 /** Compressor for this stream. */
46 protected final Deflater def;
47
48 /** Input buffer for reading compressed data. */
49 protected final byte[] buf;
50
51 /** Temporary read buffer. */
52 private byte[] rbuf = new byte[1];
53
54 /** Default compressor is used. */
55 private boolean usesDefaultDeflater = false;
56
57 /** End of the underlying input stream has been reached. */
58 private boolean reachEOF = false;
59
60 /**
61 * Check to make sure that this stream has not been closed.
62 */
63 private void ensureOpen() throws IOException {
64 if (in == null) {
65 throw new IOException("Stream closed");
66 }
67 }
68
69 /**
70 * Creates a new input stream with a default compressor and buffer
71 * size.
72 *
73 * @param in input stream to read the uncompressed data to
74 * @throws NullPointerException if {@code in} is null
75 */
76 public DeflaterInputStream(InputStream in) {
77 this(in, new Deflater());
78 usesDefaultDeflater = true;
79 }
80
81 /**
82 * Creates a new input stream with the specified compressor and a
83 * default buffer size.
84 *
85 * @param in input stream to read the uncompressed data to
86 * @param defl compressor ("deflater") for this stream
87 * @throws NullPointerException if {@code in} or {@code defl} is null
88 */
89 public DeflaterInputStream(InputStream in, Deflater defl) {
90 this(in, defl, 512);
91 }
92
93 /**
94 * Creates a new input stream with the specified compressor and buffer
95 * size.
96 *
97 * @param in input stream to read the uncompressed data to
98 * @param defl compressor ("deflater") for this stream
99 * @param bufLen compression buffer size
100 * @throws IllegalArgumentException if {@code bufLen} is <= 0
101 * @throws NullPointerException if {@code in} or {@code defl} is null
102 */
103 public DeflaterInputStream(InputStream in, Deflater defl, int bufLen) {
104 super(in);
105
106 // Sanity checks
107 if (in == null)
108 throw new NullPointerException("Null input");
109 if (defl == null)
110 throw new NullPointerException("Null deflater");
111 if (bufLen < 1)
112 throw new IllegalArgumentException("Buffer size < 1");
113
114 // Initialize
115 def = defl;
116 buf = new byte[bufLen];
117 }
118
119 /**
120 * Closes this input stream and its underlying input stream, discarding
121 * any pending uncompressed data.
122 *
123 * @throws IOException if an I/O error occurs
124 */
125 public void close() throws IOException {
126 if (in != null) {
127 try {
128 // Clean up
129 if (usesDefaultDeflater) {
130 def.end();
131 }
132
133 in.close();
134 } finally {
135 in = null;
136 }
137 }
138 }
139
140 /**
141 * Reads a single byte of compressed data from the input stream.
142 * This method will block until some input can be read and compressed.
143 *
144 * @return a single byte of compressed data, or -1 if the end of the
145 * uncompressed input stream is reached
146 * @throws IOException if an I/O error occurs or if this stream is
147 * already closed
148 */
149 public int read() throws IOException {
150 // Read a single byte of compressed data
151 int len = read(rbuf, 0, 1);
152 if (len <= 0)
153 return -1;
154 return (rbuf[0] & 0xFF);
155 }
156
157 /**
158 * Reads compressed data into a byte array.
159 * This method will block until some input can be read and compressed.
160 *
161 * @param b buffer into which the data is read
162 * @param off starting offset of the data within {@code b}
163 * @param len maximum number of compressed bytes to read into {@code b}
164 * @return the actual number of bytes read, or -1 if the end of the
165 * uncompressed input stream is reached
166 * @throws IndexOutOfBoundsException if {@code len} > {@code b.length -
167 * off}
168 * @throws IOException if an I/O error occurs or if this input stream is
169 * already closed
170 */
171 public int read(byte[] b, int off, int len) throws IOException {
172 // Sanity checks
173 ensureOpen();
174 if (b == null) {
175 throw new NullPointerException("Null buffer for read");
176 } else if (off < 0 || len < 0 || len > b.length - off) {
177 throw new IndexOutOfBoundsException();
178 } else if (len == 0) {
179 return 0;
180 }
181
182 // Read and compress (deflate) input data bytes
183 int cnt = 0;
184 while (len > 0 && !def.finished()) {
185 int n;
186
187 // Read data from the input stream
188 if (def.needsInput()) {
189 n = in.read(buf, 0, buf.length);
190 if (n < 0) {
191 // End of the input stream reached
192 def.finish();
193 } else if (n > 0) {
194 def.setInput(buf, 0, n);
195 }
196 }
197
198 // Compress the input data, filling the read buffer
199 n = def.deflate(b, off, len);
200 cnt += n;
201 off += n;
202 len -= n;
203 }
204 if (cnt == 0 && def.finished()) {
205 reachEOF = true;
206 cnt = -1;
207 }
208
209 return cnt;
210 }
211
212 /**
213 * Skips over and discards data from the input stream.
214 * This method may block until the specified number of bytes are read and
215 * skipped. <em>Note:</em> While {@code n} is given as a {@code long},
216 * the maximum number of bytes which can be skipped is
217 * {@code Integer.MAX_VALUE}.
218 *
219 * @param n number of bytes to be skipped
220 * @return the actual number of bytes skipped
221 * @throws IOException if an I/O error occurs or if this stream is
222 * already closed
223 */
224 public long skip(long n) throws IOException {
225 if (n < 0) {
226 throw new IllegalArgumentException("negative skip length");
227 }
228 ensureOpen();
229
230 // Skip bytes by repeatedly decompressing small blocks
231 if (rbuf.length < 512)
232 rbuf = new byte[512];
233
234 int total = (int)Math.min(n, Integer.MAX_VALUE);
235 long cnt = 0;
236 while (total > 0) {
237 // Read a small block of uncompressed bytes
238 int len = read(rbuf, 0, (total <= rbuf.length ? total : rbuf.length));
239
240 if (len < 0) {
241 break;
242 }
243 cnt += len;
244 total -= len;
245 }
246 return cnt;
247 }
248
249 /**
250 * Returns 0 after EOF has been reached, otherwise always return 1.
251 * <p>
252 * Programs should not count on this method to return the actual number
253 * of bytes that could be read without blocking
254 * @return zero after the end of the underlying input stream has been
255 * reached, otherwise always returns 1
256 * @throws IOException if an I/O error occurs or if this stream is
257 * already closed
258 */
259 public int available() throws IOException {
260 ensureOpen();
261 if (reachEOF) {
262 return 0;
263 }
264 return 1;
265 }
266
267 /**
268 * Always returns {@code false} because this input stream does not support
269 * the {@link #mark mark()} and {@link #reset reset()} methods.
270 *
271 * @return false, always
272 */
273 public boolean markSupported() {
274 return false;
275 }
276
277 /**
278 * <i>This operation is not supported</i>.
279 *
280 * @param limit maximum bytes that can be read before invalidating the position marker
281 */
282 public void mark(int limit) {
283 // Operation not supported
284 }
285
286 /**
287 * <i>This operation is not supported</i>.
288 *
289 * @throws IOException always thrown
290 */
291 public void reset() throws IOException {
292 throw new IOException("mark/reset not supported");
293 }
294 }
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