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| 1 | /* | ||
| 2 | * Copyright (c) 1994, 2010, 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 <code>ByteArrayInputStream</code> contains | ||
| 30 | * an internal buffer that contains bytes that | ||
| 31 | * may be read from the stream. An internal | ||
| 32 | * counter keeps track of the next byte to | ||
| 33 | * be supplied by the <code>read</code> method. | ||
| 34 | * <p> | ||
| 35 | * Closing a <tt>ByteArrayInputStream</tt> has no effect. The methods in | ||
| 36 | * this class can be called after the stream has been closed without | ||
| 37 | * generating an <tt>IOException</tt>. | ||
| 38 | * | ||
| 39 | * @author Arthur van Hoff | ||
| 40 | * @see java.io.StringBufferInputStream | ||
| 41 | * @since JDK1.0 | ||
| 42 | */ | ||
| 43 | public | ||
| 44 | class ByteArrayInputStream extends InputStream { | ||
| 45 | |||
| 46 | /** | ||
| 47 | * An array of bytes that was provided | ||
| 48 | * by the creator of the stream. Elements <code>buf[0]</code> | ||
| 49 | * through <code>buf[count-1]</code> are the | ||
| 50 | * only bytes that can ever be read from the | ||
| 51 | * stream; element <code>buf[pos]</code> is | ||
| 52 | * the next byte to be read. | ||
| 53 | */ | ||
| 54 | protected byte buf[]; | ||
| 55 | |||
| 56 | /** | ||
| 57 | * The index of the next character to read from the input stream buffer. | ||
| 58 | * This value should always be nonnegative | ||
| 59 | * and not larger than the value of <code>count</code>. | ||
| 60 | * The next byte to be read from the input stream buffer | ||
| 61 | * will be <code>buf[pos]</code>. | ||
| 62 | */ | ||
| 63 | protected int pos; | ||
| 64 | |||
| 65 | /** | ||
| 66 | * The currently marked position in the stream. | ||
| 67 | * ByteArrayInputStream objects are marked at position zero by | ||
| 68 | * default when constructed. They may be marked at another | ||
| 69 | * position within the buffer by the <code>mark()</code> method. | ||
| 70 | * The current buffer position is set to this point by the | ||
| 71 | * <code>reset()</code> method. | ||
| 72 | * <p> | ||
| 73 | * If no mark has been set, then the value of mark is the offset | ||
| 74 | * passed to the constructor (or 0 if the offset was not supplied). | ||
| 75 | * | ||
| 76 | * @since JDK1.1 | ||
| 77 | */ | ||
| 78 | protected int mark = 0; | ||
| 79 | |||
| 80 | /** | ||
| 81 | * The index one greater than the last valid character in the input | ||
| 82 | * stream buffer. | ||
| 83 | * This value should always be nonnegative | ||
| 84 | * and not larger than the length of <code>buf</code>. | ||
| 85 | * It is one greater than the position of | ||
| 86 | * the last byte within <code>buf</code> that | ||
| 87 | * can ever be read from the input stream buffer. | ||
| 88 | */ | ||
| 89 | protected int count; | ||
| 90 | |||
| 91 | /** | ||
| 92 | * Creates a <code>ByteArrayInputStream</code> | ||
| 93 | * so that it uses <code>buf</code> as its | ||
| 94 | * buffer array. | ||
| 95 | * The buffer array is not copied. | ||
| 96 | * The initial value of <code>pos</code> | ||
| 97 | * is <code>0</code> and the initial value | ||
| 98 | * of <code>count</code> is the length of | ||
| 99 | * <code>buf</code>. | ||
| 100 | * | ||
| 101 | * @param buf the input buffer. | ||
| 102 | */ | ||
| 103 | public ByteArrayInputStream(byte buf[]) { | ||
| 104 | this.buf = buf; | ||
| 105 | this.pos = 0; | ||
| 106 | this.count = buf.length; | ||
| 107 | } | ||
| 108 | |||
| 109 | /** | ||
| 110 | * Creates <code>ByteArrayInputStream</code> | ||
| 111 | * that uses <code>buf</code> as its | ||
| 112 | * buffer array. The initial value of <code>pos</code> | ||
| 113 | * is <code>offset</code> and the initial value | ||
| 114 | * of <code>count</code> is the minimum of <code>offset+length</code> | ||
| 115 | * and <code>buf.length</code>. | ||
| 116 | * The buffer array is not copied. The buffer's mark is | ||
| 117 | * set to the specified offset. | ||
| 118 | * | ||
| 119 | * @param buf the input buffer. | ||
| 120 | * @param offset the offset in the buffer of the first byte to read. | ||
| 121 | * @param length the maximum number of bytes to read from the buffer. | ||
| 122 | */ | ||
| 123 | public ByteArrayInputStream(byte buf[], int offset, int length) { | ||
| 124 | this.buf = buf; | ||
| 125 | this.pos = offset; | ||
| 126 | this.count = Math.min(offset + length, buf.length); | ||
| 127 | this.mark = offset; | ||
| 128 | } | ||
| 129 | |||
| 130 | /** | ||
| 131 | * Reads the next byte of data from this input stream. The value | ||
| 132 | * byte is returned as an <code>int</code> in the range | ||
| 133 | * <code>0</code> to <code>255</code>. If no byte is available | ||
| 134 | * because the end of the stream has been reached, the value | ||
| 135 | * <code>-1</code> is returned. | ||
| 136 | * <p> | ||
| 137 | * This <code>read</code> method | ||
| 138 | * cannot block. | ||
| 139 | * | ||
| 140 | * @return the next byte of data, or <code>-1</code> if the end of the | ||
| 141 | * stream has been reached. | ||
| 142 | */ | ||
| 143 | public synchronized int read() { | ||
| 144 | return (pos < count) ? (buf[pos++] & 0xff) : -1; | ||
| 145 | } | ||
| 146 | |||
| 147 | /** | ||
| 148 | * Reads up to <code>len</code> bytes of data into an array of bytes | ||
| 149 | * from this input stream. | ||
| 150 | * If <code>pos</code> equals <code>count</code>, | ||
| 151 | * then <code>-1</code> is returned to indicate | ||
| 152 | * end of file. Otherwise, the number <code>k</code> | ||
| 153 | * of bytes read is equal to the smaller of | ||
| 154 | * <code>len</code> and <code>count-pos</code>. | ||
| 155 | * If <code>k</code> is positive, then bytes | ||
| 156 | * <code>buf[pos]</code> through <code>buf[pos+k-1]</code> | ||
| 157 | * are copied into <code>b[off]</code> through | ||
| 158 | * <code>b[off+k-1]</code> in the manner performed | ||
| 159 | * by <code>System.arraycopy</code>. The | ||
| 160 | * value <code>k</code> is added into <code>pos</code> | ||
| 161 | * and <code>k</code> is returned. | ||
| 162 | * <p> | ||
| 163 | * This <code>read</code> method cannot block. | ||
| 164 | * | ||
| 165 | * @param b the buffer into which the data is read. | ||
| 166 | * @param off the start offset in the destination array <code>b</code> | ||
| 167 | * @param len the maximum number of bytes read. | ||
| 168 | * @return the total number of bytes read into the buffer, or | ||
| 169 | * <code>-1</code> if there is no more data because the end of | ||
| 170 | * the stream has been reached. | ||
| 171 | * @exception NullPointerException If <code>b</code> is <code>null</code>. | ||
| 172 | * @exception IndexOutOfBoundsException If <code>off</code> is negative, | ||
| 173 | * <code>len</code> is negative, or <code>len</code> is greater than | ||
| 174 | * <code>b.length - off</code> | ||
| 175 | */ | ||
| 176 | public synchronized int read(byte b[], int off, int len) { | ||
| 177 | if (b == null) { | ||
| 178 | throw new NullPointerException(); | ||
| 179 | } else if (off < 0 || len < 0 || len > b.length - off) { | ||
| 180 | throw new IndexOutOfBoundsException(); | ||
| 181 | } | ||
| 182 | |||
| 183 | if (pos >= count) { | ||
| 184 | return -1; | ||
| 185 | } | ||
| 186 | |||
| 187 | int avail = count - pos; | ||
| 188 | if (len > avail) { | ||
| 189 | len = avail; | ||
| 190 | } | ||
| 191 | if (len <= 0) { | ||
| 192 | return 0; | ||
| 193 | } | ||
| 194 | System.arraycopy(buf, pos, b, off, len); | ||
| 195 | pos += len; | ||
| 196 | return len; | ||
| 197 | } | ||
| 198 | |||
| 199 | /** | ||
| 200 | * Skips <code>n</code> bytes of input from this input stream. Fewer | ||
| 201 | * bytes might be skipped if the end of the input stream is reached. | ||
| 202 | * The actual number <code>k</code> | ||
| 203 | * of bytes to be skipped is equal to the smaller | ||
| 204 | * of <code>n</code> and <code>count-pos</code>. | ||
| 205 | * The value <code>k</code> is added into <code>pos</code> | ||
| 206 | * and <code>k</code> is returned. | ||
| 207 | * | ||
| 208 | * @param n the number of bytes to be skipped. | ||
| 209 | * @return the actual number of bytes skipped. | ||
| 210 | */ | ||
| 211 | public synchronized long skip(long n) { | ||
| 212 | long k = count - pos; | ||
| 213 | if (n < k) { | ||
| 214 | k = n < 0 ? 0 : n; | ||
| 215 | } | ||
| 216 | |||
| 217 | pos += k; | ||
| 218 | return k; | ||
| 219 | } | ||
| 220 | |||
| 221 | /** | ||
| 222 | * Returns the number of remaining bytes that can be read (or skipped over) | ||
| 223 | * from this input stream. | ||
| 224 | * <p> | ||
| 225 | * The value returned is <code>count - pos</code>, | ||
| 226 | * which is the number of bytes remaining to be read from the input buffer. | ||
| 227 | * | ||
| 228 | * @return the number of remaining bytes that can be read (or skipped | ||
| 229 | * over) from this input stream without blocking. | ||
| 230 | */ | ||
| 231 | public synchronized int available() { | ||
| 232 | return count - pos; | ||
| 233 | } | ||
| 234 | |||
| 235 | /** | ||
| 236 | * Tests if this <code>InputStream</code> supports mark/reset. The | ||
| 237 | * <code>markSupported</code> method of <code>ByteArrayInputStream</code> | ||
| 238 | * always returns <code>true</code>. | ||
| 239 | * | ||
| 240 | * @since JDK1.1 | ||
| 241 | */ | ||
| 242 | public boolean markSupported() { | ||
| 243 | return true; | ||
| 244 | } | ||
| 245 | |||
| 246 | /** | ||
| 247 | * Set the current marked position in the stream. | ||
| 248 | * ByteArrayInputStream objects are marked at position zero by | ||
| 249 | * default when constructed. They may be marked at another | ||
| 250 | * position within the buffer by this method. | ||
| 251 | * <p> | ||
| 252 | * If no mark has been set, then the value of the mark is the | ||
| 253 | * offset passed to the constructor (or 0 if the offset was not | ||
| 254 | * supplied). | ||
| 255 | * | ||
| 256 | * <p> Note: The <code>readAheadLimit</code> for this class | ||
| 257 | * has no meaning. | ||
| 258 | * | ||
| 259 | * @since JDK1.1 | ||
| 260 | */ | ||
| 261 | public void mark(int readAheadLimit) { | ||
| 262 | mark = pos; | ||
| 263 | } | ||
| 264 | |||
| 265 | /** | ||
| 266 | * Resets the buffer to the marked position. The marked position | ||
| 267 | * is 0 unless another position was marked or an offset was specified | ||
| 268 | * in the constructor. | ||
| 269 | */ | ||
| 270 | public synchronized void reset() { | ||
| 271 | pos = mark; | ||
| 272 | } | ||
| 273 | |||
| 274 | /** | ||
| 275 | * Closing a <tt>ByteArrayInputStream</tt> has no effect. The methods in | ||
| 276 | * this class can be called after the stream has been closed without | ||
| 277 | * generating an <tt>IOException</tt>. | ||
| 278 | * <p> | ||
| 279 | */ | ||
| 280 | public void close() throws IOException { | ||
| 281 | } | ||
| 282 | |||
| 283 | } | ||