1 /*
2 * Copyright (c) 1994, 2019, Oracle and/or its affiliates. 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. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.io;
27
28 /**
29 * A data output stream lets an application write primitive Java data
30 * types to an output stream in a portable way. An application can
31 * then use a data input stream to read the data back in.
32 *
33 * @author unascribed
34 * @see java.io.DataInputStream
35 * @since 1.0
36 */
37 public
38 class DataOutputStream extends FilterOutputStream implements DataOutput {
39 /**
40 * The number of bytes written to the data output stream so far.
41 * If this counter overflows, it will be wrapped to Integer.MAX_VALUE.
42 */
43 protected int written;
44
45 /**
46 * bytearr is initialized on demand by writeUTF
47 */
48 private byte[] bytearr = null;
49
50 /**
51 * Creates a new data output stream to write data to the specified
52 * underlying output stream. The counter <code>written</code> is
53 * set to zero.
54 *
55 * @param out the underlying output stream, to be saved for later
56 * use.
57 * @see java.io.FilterOutputStream#out
58 */
59 public DataOutputStream(OutputStream out) {
60 super(out);
61 if (out == null) {
62 throw new NullPointerException();
63 }
64 }
65
66 /**
67 * Increases the written counter by the specified value
68 * until it reaches Integer.MAX_VALUE.
69 */
70 private void incCount(int value) {
71 int temp = written + value;
72 if (temp < 0) {
73 temp = Integer.MAX_VALUE;
74 }
75 written = temp;
76 }
77
78 /**
79 * Writes the specified byte (the low eight bits of the argument
80 * <code>b</code>) to the underlying output stream. If no exception
81 * is thrown, the counter <code>written</code> is incremented by
82 * <code>1</code>.
83 * <p>
84 * Implements the <code>write</code> method of <code>OutputStream</code>.
85 *
86 * @param b the <code>byte</code> to be written.
87 * @exception IOException if an I/O error occurs.
88 * @see java.io.FilterOutputStream#out
89 */
90 public synchronized void write(int b) throws IOException {
91 out.write(b);
92 incCount(1);
93 }
94
95 /**
96 * Writes <code>len</code> bytes from the specified byte array
97 * starting at offset <code>off</code> to the underlying output stream.
98 * If no exception is thrown, the counter <code>written</code> is
99 * incremented by <code>len</code>.
100 *
101 * @param b the data.
102 * @param off the start offset in the data.
103 * @param len the number of bytes to write.
104 * @exception IOException if an I/O error occurs.
105 * @see java.io.FilterOutputStream#out
106 */
107 public synchronized void write(byte b[], int off, int len)
108 throws IOException
109 {
110 out.write(b, off, len);
111 incCount(len);
112 }
113
114 /**
115 * Flushes this data output stream. This forces any buffered output
116 * bytes to be written out to the stream.
117 * <p>
118 * The <code>flush</code> method of <code>DataOutputStream</code>
119 * calls the <code>flush</code> method of its underlying output stream.
120 *
121 * @exception IOException if an I/O error occurs.
122 * @see java.io.FilterOutputStream#out
123 * @see java.io.OutputStream#flush()
124 */
125 public void flush() throws IOException {
126 out.flush();
127 }
128
129 /**
130 * Writes a <code>boolean</code> to the underlying output stream as
131 * a 1-byte value. The value <code>true</code> is written out as the
132 * value <code>(byte)1</code>; the value <code>false</code> is
133 * written out as the value <code>(byte)0</code>. If no exception is
134 * thrown, the counter <code>written</code> is incremented by
135 * <code>1</code>.
136 *
137 * @param v a <code>boolean</code> value to be written.
138 * @exception IOException if an I/O error occurs.
139 * @see java.io.FilterOutputStream#out
140 */
141 public final void writeBoolean(boolean v) throws IOException {
142 out.write(v ? 1 : 0);
143 incCount(1);
144 }
145
146 /**
147 * Writes out a <code>byte</code> to the underlying output stream as
148 * a 1-byte value. If no exception is thrown, the counter
149 * <code>written</code> is incremented by <code>1</code>.
150 *
151 * @param v a <code>byte</code> value to be written.
152 * @exception IOException if an I/O error occurs.
153 * @see java.io.FilterOutputStream#out
154 */
155 public final void writeByte(int v) throws IOException {
156 out.write(v);
157 incCount(1);
158 }
159
160 /**
161 * Writes a <code>short</code> to the underlying output stream as two
162 * bytes, high byte first. If no exception is thrown, the counter
163 * <code>written</code> is incremented by <code>2</code>.
164 *
165 * @param v a <code>short</code> to be written.
166 * @exception IOException if an I/O error occurs.
167 * @see java.io.FilterOutputStream#out
168 */
169 public final void writeShort(int v) throws IOException {
170 out.write((v >>> 8) & 0xFF);
171 out.write((v >>> 0) & 0xFF);
172 incCount(2);
173 }
174
175 /**
176 * Writes a <code>char</code> to the underlying output stream as a
177 * 2-byte value, high byte first. If no exception is thrown, the
178 * counter <code>written</code> is incremented by <code>2</code>.
179 *
180 * @param v a <code>char</code> value to be written.
181 * @exception IOException if an I/O error occurs.
182 * @see java.io.FilterOutputStream#out
183 */
184 public final void writeChar(int v) throws IOException {
185 out.write((v >>> 8) & 0xFF);
186 out.write((v >>> 0) & 0xFF);
187 incCount(2);
188 }
189
190 /**
191 * Writes an <code>int</code> to the underlying output stream as four
192 * bytes, high byte first. If no exception is thrown, the counter
193 * <code>written</code> is incremented by <code>4</code>.
194 *
195 * @param v an <code>int</code> to be written.
196 * @exception IOException if an I/O error occurs.
197 * @see java.io.FilterOutputStream#out
198 */
199 public final void writeInt(int v) throws IOException {
200 out.write((v >>> 24) & 0xFF);
201 out.write((v >>> 16) & 0xFF);
202 out.write((v >>> 8) & 0xFF);
203 out.write((v >>> 0) & 0xFF);
204 incCount(4);
205 }
206
207 private byte writeBuffer[] = new byte[8];
208
209 /**
210 * Writes a <code>long</code> to the underlying output stream as eight
211 * bytes, high byte first. In no exception is thrown, the counter
212 * <code>written</code> is incremented by <code>8</code>.
213 *
214 * @param v a <code>long</code> to be written.
215 * @exception IOException if an I/O error occurs.
216 * @see java.io.FilterOutputStream#out
217 */
218 public final void writeLong(long v) throws IOException {
219 writeBuffer[0] = (byte)(v >>> 56);
220 writeBuffer[1] = (byte)(v >>> 48);
221 writeBuffer[2] = (byte)(v >>> 40);
222 writeBuffer[3] = (byte)(v >>> 32);
223 writeBuffer[4] = (byte)(v >>> 24);
224 writeBuffer[5] = (byte)(v >>> 16);
225 writeBuffer[6] = (byte)(v >>> 8);
226 writeBuffer[7] = (byte)(v >>> 0);
227 out.write(writeBuffer, 0, 8);
228 incCount(8);
229 }
230
231 /**
232 * Converts the float argument to an <code>int</code> using the
233 * <code>floatToIntBits</code> method in class <code>Float</code>,
234 * and then writes that <code>int</code> value to the underlying
235 * output stream as a 4-byte quantity, high byte first. If no
236 * exception is thrown, the counter <code>written</code> is
237 * incremented by <code>4</code>.
238 *
239 * @param v a <code>float</code> value to be written.
240 * @exception IOException if an I/O error occurs.
241 * @see java.io.FilterOutputStream#out
242 * @see java.lang.Float#floatToIntBits(float)
243 */
244 public final void writeFloat(float v) throws IOException {
245 writeInt(Float.floatToIntBits(v));
246 }
247
248 /**
249 * Converts the double argument to a <code>long</code> using the
250 * <code>doubleToLongBits</code> method in class <code>Double</code>,
251 * and then writes that <code>long</code> value to the underlying
252 * output stream as an 8-byte quantity, high byte first. If no
253 * exception is thrown, the counter <code>written</code> is
254 * incremented by <code>8</code>.
255 *
256 * @param v a <code>double</code> value to be written.
257 * @exception IOException if an I/O error occurs.
258 * @see java.io.FilterOutputStream#out
259 * @see java.lang.Double#doubleToLongBits(double)
260 */
261 public final void writeDouble(double v) throws IOException {
262 writeLong(Double.doubleToLongBits(v));
263 }
264
265 /**
266 * Writes out the string to the underlying output stream as a
267 * sequence of bytes. Each character in the string is written out, in
268 * sequence, by discarding its high eight bits. If no exception is
269 * thrown, the counter <code>written</code> is incremented by the
270 * length of <code>s</code>.
271 *
272 * @param s a string of bytes to be written.
273 * @exception IOException if an I/O error occurs.
274 * @see java.io.FilterOutputStream#out
275 */
276 public final void writeBytes(String s) throws IOException {
277 int len = s.length();
278 for (int i = 0 ; i < len ; i++) {
279 out.write((byte)s.charAt(i));
280 }
281 incCount(len);
282 }
283
284 /**
285 * Writes a string to the underlying output stream as a sequence of
286 * characters. Each character is written to the data output stream as
287 * if by the <code>writeChar</code> method. If no exception is
288 * thrown, the counter <code>written</code> is incremented by twice
289 * the length of <code>s</code>.
290 *
291 * @param s a <code>String</code> value to be written.
292 * @exception IOException if an I/O error occurs.
293 * @see java.io.DataOutputStream#writeChar(int)
294 * @see java.io.FilterOutputStream#out
295 */
296 public final void writeChars(String s) throws IOException {
297 int len = s.length();
298 for (int i = 0 ; i < len ; i++) {
299 int v = s.charAt(i);
300 out.write((v >>> 8) & 0xFF);
301 out.write((v >>> 0) & 0xFF);
302 }
303 incCount(len * 2);
304 }
305
306 /**
307 * Writes a string to the underlying output stream using
308 * <a href="DataInput.html#modified-utf-8">modified UTF-8</a>
309 * encoding in a machine-independent manner.
310 * <p>
311 * First, two bytes are written to the output stream as if by the
312 * <code>writeShort</code> method giving the number of bytes to
313 * follow. This value is the number of bytes actually written out,
314 * not the length of the string. Following the length, each character
315 * of the string is output, in sequence, using the modified UTF-8 encoding
316 * for the character. If no exception is thrown, the counter
317 * <code>written</code> is incremented by the total number of
318 * bytes written to the output stream. This will be at least two
319 * plus the length of <code>str</code>, and at most two plus
320 * thrice the length of <code>str</code>.
321 *
322 * @param str a string to be written.
323 * @throws UTFDataFormatException if the modified UTF-8 encoding of
324 * {@code str} would exceed 65535 bytes in length
325 * @throws IOException if some other I/O error occurs.
326 * @see #writeChars(String)
327 */
328 public final void writeUTF(String str) throws IOException {
329 writeUTF(str, this);
330 }
331
332 /**
333 * Writes a string to the specified DataOutput using
334 * <a href="DataInput.html#modified-utf-8">modified UTF-8</a>
335 * encoding in a machine-independent manner.
336 * <p>
337 * First, two bytes are written to out as if by the <code>writeShort</code>
338 * method giving the number of bytes to follow. This value is the number of
339 * bytes actually written out, not the length of the string. Following the
340 * length, each character of the string is output, in sequence, using the
341 * modified UTF-8 encoding for the character. If no exception is thrown, the
342 * counter <code>written</code> is incremented by the total number of
343 * bytes written to the output stream. This will be at least two
344 * plus the length of <code>str</code>, and at most two plus
345 * thrice the length of <code>str</code>.
346 *
347 * @param str a string to be written.
348 * @param out destination to write to
349 * @return The number of bytes written out.
350 * @throws UTFDataFormatException if the modified UTF-8 encoding of
351 * {@code str} would exceed 65535 bytes in length
352 * @throws IOException if some other I/O error occurs.
353 */
354 static int writeUTF(String str, DataOutput out) throws IOException {
355 final int strlen = str.length();
356 int utflen = strlen; // optimized for ASCII
357
358 for (int i = 0; i < strlen; i++) {
359 int c = str.charAt(i);
360 if (c >= 0x80 || c == 0)
361 utflen += (c >= 0x800) ? 2 : 1;
362 }
363
364 if (utflen > 65535 || /* overflow */ utflen < strlen)
365 throw new UTFDataFormatException(tooLongMsg(str, utflen));
366
367 final byte[] bytearr;
368 if (out instanceof DataOutputStream) {
369 DataOutputStream dos = (DataOutputStream)out;
370 if (dos.bytearr == null || (dos.bytearr.length < (utflen + 2)))
371 dos.bytearr = new byte[(utflen*2) + 2];
372 bytearr = dos.bytearr;
373 } else {
374 bytearr = new byte[utflen + 2];
375 }
376
377 int count = 0;
378 bytearr[count++] = (byte) ((utflen >>> 8) & 0xFF);
379 bytearr[count++] = (byte) ((utflen >>> 0) & 0xFF);
380
381 int i = 0;
382 for (i = 0; i < strlen; i++) { // optimized for initial run of ASCII
383 int c = str.charAt(i);
384 if (c >= 0x80 || c == 0) break;
385 bytearr[count++] = (byte) c;
386 }
387
388 for (; i < strlen; i++) {
389 int c = str.charAt(i);
390 if (c < 0x80 && c != 0) {
391 bytearr[count++] = (byte) c;
392 } else if (c >= 0x800) {
393 bytearr[count++] = (byte) (0xE0 | ((c >> 12) & 0x0F));
394 bytearr[count++] = (byte) (0x80 | ((c >> 6) & 0x3F));
395 bytearr[count++] = (byte) (0x80 | ((c >> 0) & 0x3F));
396 } else {
397 bytearr[count++] = (byte) (0xC0 | ((c >> 6) & 0x1F));
398 bytearr[count++] = (byte) (0x80 | ((c >> 0) & 0x3F));
399 }
400 }
401 out.write(bytearr, 0, utflen + 2);
402 return utflen + 2;
403 }
404
405 private static String tooLongMsg(String s, int bits32) {
406 int slen = s.length();
407 String head = s.substring(0, 8);
408 String tail = s.substring(slen - 8, slen);
409 // handle int overflow with max 3x expansion
410 long actualLength = (long)slen + Integer.toUnsignedLong(bits32 - slen);
411 return "encoded string (" + head + "..." + tail + ") too long: "
412 + actualLength + " bytes";
413 }
414
415 /**
416 * Returns the current value of the counter <code>written</code>,
417 * the number of bytes written to this data output stream so far.
418 * If the counter overflows, it will be wrapped to Integer.MAX_VALUE.
419 *
420 * @return the value of the <code>written</code> field.
421 * @see java.io.DataOutputStream#written
422 */
423 public final int size() {
424 return written;
425 }
426 }