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| 1 | +/* | |
| 2 | + * Copyright (c) 1996, 2005, 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 | +/** | |
| 30 | + * Abstract class for writing to character streams. The only methods that a | |
| 31 | + * subclass must implement are write(char[], int, int), flush(), and close(). | |
| 32 | + * Most subclasses, however, will override some of the methods defined here in | |
| 33 | + * order to provide higher efficiency, additional functionality, or both. | |
| 34 | + * | |
| 35 | + * @see Writer | |
| 36 | + * @see BufferedWriter | |
| 37 | + * @see CharArrayWriter | |
| 38 | + * @see FilterWriter | |
| 39 | + * @see OutputStreamWriter | |
| 40 | + * @see FileWriter | |
| 41 | + * @see PipedWriter | |
| 42 | + * @see PrintWriter | |
| 43 | + * @see StringWriter | |
| 44 | + * @see Reader | |
| 45 | + * | |
| 46 | + * @author Mark Reinhold | |
| 47 | + * @since JDK1.1 | |
| 48 | + */ | |
| 49 | + | |
| 50 | +public abstract class Writer implements Appendable, Closeable, Flushable { | |
| 51 | + | |
| 52 | + /** | |
| 53 | + * Temporary buffer used to hold writes of strings and single characters | |
| 54 | + */ | |
| 55 | + private char[] writeBuffer; | |
| 56 | + | |
| 57 | + /** | |
| 58 | + * Size of writeBuffer, must be >= 1 | |
| 59 | + */ | |
| 60 | + private final int writeBufferSize = 1024; | |
| 61 | + | |
| 62 | + /** | |
| 63 | + * The object used to synchronize operations on this stream. For | |
| 64 | + * efficiency, a character-stream object may use an object other than | |
| 65 | + * itself to protect critical sections. A subclass should therefore use | |
| 66 | + * the object in this field rather than <tt>this</tt> or a synchronized | |
| 67 | + * method. | |
| 68 | + */ | |
| 69 | + protected Object lock; | |
| 70 | + | |
| 71 | + /** | |
| 72 | + * Creates a new character-stream writer whose critical sections will | |
| 73 | + * synchronize on the writer itself. | |
| 74 | + */ | |
| 75 | + protected Writer() { | |
| 76 | + this.lock = this; | |
| 77 | + } | |
| 78 | + | |
| 79 | + /** | |
| 80 | + * Creates a new character-stream writer whose critical sections will | |
| 81 | + * synchronize on the given object. | |
| 82 | + * | |
| 83 | + * @param lock | |
| 84 | + * Object to synchronize on | |
| 85 | + */ | |
| 86 | + protected Writer(Object lock) { | |
| 87 | + if (lock == null) { | |
| 88 | + throw new NullPointerException(); | |
| 89 | + } | |
| 90 | + this.lock = lock; | |
| 91 | + } | |
| 92 | + | |
| 93 | + /** | |
| 94 | + * Writes a single character. The character to be written is contained in | |
| 95 | + * the 16 low-order bits of the given integer value; the 16 high-order bits | |
| 96 | + * are ignored. | |
| 97 | + * | |
| 98 | + * <p> Subclasses that intend to support efficient single-character output | |
| 99 | + * should override this method. | |
| 100 | + * | |
| 101 | + * @param c | |
| 102 | + * int specifying a character to be written | |
| 103 | + * | |
| 104 | + * @throws IOException | |
| 105 | + * If an I/O error occurs | |
| 106 | + */ | |
| 107 | + public void write(int c) throws IOException { | |
| 108 | + synchronized (lock) { | |
| 109 | + if (writeBuffer == null){ | |
| 110 | + writeBuffer = new char[writeBufferSize]; | |
| 111 | + } | |
| 112 | + writeBuffer[0] = (char) c; | |
| 113 | + write(writeBuffer, 0, 1); | |
| 114 | + } | |
| 115 | + } | |
| 116 | + | |
| 117 | + /** | |
| 118 | + * Writes an array of characters. | |
| 119 | + * | |
| 120 | + * @param cbuf | |
| 121 | + * Array of characters to be written | |
| 122 | + * | |
| 123 | + * @throws IOException | |
| 124 | + * If an I/O error occurs | |
| 125 | + */ | |
| 126 | + public void write(char cbuf[]) throws IOException { | |
| 127 | + write(cbuf, 0, cbuf.length); | |
| 128 | + } | |
| 129 | + | |
| 130 | + /** | |
| 131 | + * Writes a portion of an array of characters. | |
| 132 | + * | |
| 133 | + * @param cbuf | |
| 134 | + * Array of characters | |
| 135 | + * | |
| 136 | + * @param off | |
| 137 | + * Offset from which to start writing characters | |
| 138 | + * | |
| 139 | + * @param len | |
| 140 | + * Number of characters to write | |
| 141 | + * | |
| 142 | + * @throws IOException | |
| 143 | + * If an I/O error occurs | |
| 144 | + */ | |
| 145 | + abstract public void write(char cbuf[], int off, int len) throws IOException; | |
| 146 | + | |
| 147 | + /** | |
| 148 | + * Writes a string. | |
| 149 | + * | |
| 150 | + * @param str | |
| 151 | + * String to be written | |
| 152 | + * | |
| 153 | + * @throws IOException | |
| 154 | + * If an I/O error occurs | |
| 155 | + */ | |
| 156 | + public void write(String str) throws IOException { | |
| 157 | + write(str, 0, str.length()); | |
| 158 | + } | |
| 159 | + | |
| 160 | + /** | |
| 161 | + * Writes a portion of a string. | |
| 162 | + * | |
| 163 | + * @param str | |
| 164 | + * A String | |
| 165 | + * | |
| 166 | + * @param off | |
| 167 | + * Offset from which to start writing characters | |
| 168 | + * | |
| 169 | + * @param len | |
| 170 | + * Number of characters to write | |
| 171 | + * | |
| 172 | + * @throws IndexOutOfBoundsException | |
| 173 | + * If <tt>off</tt> is negative, or <tt>len</tt> is negative, | |
| 174 | + * or <tt>off+len</tt> is negative or greater than the length | |
| 175 | + * of the given string | |
| 176 | + * | |
| 177 | + * @throws IOException | |
| 178 | + * If an I/O error occurs | |
| 179 | + */ | |
| 180 | + public void write(String str, int off, int len) throws IOException { | |
| 181 | + synchronized (lock) { | |
| 182 | + char cbuf[]; | |
| 183 | + if (len <= writeBufferSize) { | |
| 184 | + if (writeBuffer == null) { | |
| 185 | + writeBuffer = new char[writeBufferSize]; | |
| 186 | + } | |
| 187 | + cbuf = writeBuffer; | |
| 188 | + } else { // Don't permanently allocate very large buffers. | |
| 189 | + cbuf = new char[len]; | |
| 190 | + } | |
| 191 | + str.getChars(off, (off + len), cbuf, 0); | |
| 192 | + write(cbuf, 0, len); | |
| 193 | + } | |
| 194 | + } | |
| 195 | + | |
| 196 | + /** | |
| 197 | + * Appends the specified character sequence to this writer. | |
| 198 | + * | |
| 199 | + * <p> An invocation of this method of the form <tt>out.append(csq)</tt> | |
| 200 | + * behaves in exactly the same way as the invocation | |
| 201 | + * | |
| 202 | + * <pre> | |
| 203 | + * out.write(csq.toString()) </pre> | |
| 204 | + * | |
| 205 | + * <p> Depending on the specification of <tt>toString</tt> for the | |
| 206 | + * character sequence <tt>csq</tt>, the entire sequence may not be | |
| 207 | + * appended. For instance, invoking the <tt>toString</tt> method of a | |
| 208 | + * character buffer will return a subsequence whose content depends upon | |
| 209 | + * the buffer's position and limit. | |
| 210 | + * | |
| 211 | + * @param csq | |
| 212 | + * The character sequence to append. If <tt>csq</tt> is | |
| 213 | + * <tt>null</tt>, then the four characters <tt>"null"</tt> are | |
| 214 | + * appended to this writer. | |
| 215 | + * | |
| 216 | + * @return This writer | |
| 217 | + * | |
| 218 | + * @throws IOException | |
| 219 | + * If an I/O error occurs | |
| 220 | + * | |
| 221 | + * @since 1.5 | |
| 222 | + */ | |
| 223 | + public Writer append(CharSequence csq) throws IOException { | |
| 224 | + if (csq == null) | |
| 225 | + write("null"); | |
| 226 | + else | |
| 227 | + write(csq.toString()); | |
| 228 | + return this; | |
| 229 | + } | |
| 230 | + | |
| 231 | + /** | |
| 232 | + * Appends a subsequence of the specified character sequence to this writer. | |
| 233 | + * <tt>Appendable</tt>. | |
| 234 | + * | |
| 235 | + * <p> An invocation of this method of the form <tt>out.append(csq, start, | |
| 236 | + * end)</tt> when <tt>csq</tt> is not <tt>null</tt> behaves in exactly the | |
| 237 | + * same way as the invocation | |
| 238 | + * | |
| 239 | + * <pre> | |
| 240 | + * out.write(csq.subSequence(start, end).toString()) </pre> | |
| 241 | + * | |
| 242 | + * @param csq | |
| 243 | + * The character sequence from which a subsequence will be | |
| 244 | + * appended. If <tt>csq</tt> is <tt>null</tt>, then characters | |
| 245 | + * will be appended as if <tt>csq</tt> contained the four | |
| 246 | + * characters <tt>"null"</tt>. | |
| 247 | + * | |
| 248 | + * @param start | |
| 249 | + * The index of the first character in the subsequence | |
| 250 | + * | |
| 251 | + * @param end | |
| 252 | + * The index of the character following the last character in the | |
| 253 | + * subsequence | |
| 254 | + * | |
| 255 | + * @return This writer | |
| 256 | + * | |
| 257 | + * @throws IndexOutOfBoundsException | |
| 258 | + * If <tt>start</tt> or <tt>end</tt> are negative, <tt>start</tt> | |
| 259 | + * is greater than <tt>end</tt>, or <tt>end</tt> is greater than | |
| 260 | + * <tt>csq.length()</tt> | |
| 261 | + * | |
| 262 | + * @throws IOException | |
| 263 | + * If an I/O error occurs | |
| 264 | + * | |
| 265 | + * @since 1.5 | |
| 266 | + */ | |
| 267 | + public Writer append(CharSequence csq, int start, int end) throws IOException { | |
| 268 | + CharSequence cs = (csq == null ? "null" : csq); | |
| 269 | + write(cs.subSequence(start, end).toString()); | |
| 270 | + return this; | |
| 271 | + } | |
| 272 | + | |
| 273 | + /** | |
| 274 | + * Appends the specified character to this writer. | |
| 275 | + * | |
| 276 | + * <p> An invocation of this method of the form <tt>out.append(c)</tt> | |
| 277 | + * behaves in exactly the same way as the invocation | |
| 278 | + * | |
| 279 | + * <pre> | |
| 280 | + * out.write(c) </pre> | |
| 281 | + * | |
| 282 | + * @param c | |
| 283 | + * The 16-bit character to append | |
| 284 | + * | |
| 285 | + * @return This writer | |
| 286 | + * | |
| 287 | + * @throws IOException | |
| 288 | + * If an I/O error occurs | |
| 289 | + * | |
| 290 | + * @since 1.5 | |
| 291 | + */ | |
| 292 | + public Writer append(char c) throws IOException { | |
| 293 | + write(c); | |
| 294 | + return this; | |
| 295 | + } | |
| 296 | + | |
| 297 | + /** | |
| 298 | + * Flushes the stream. If the stream has saved any characters from the | |
| 299 | + * various write() methods in a buffer, write them immediately to their | |
| 300 | + * intended destination. Then, if that destination is another character or | |
| 301 | + * byte stream, flush it. Thus one flush() invocation will flush all the | |
| 302 | + * buffers in a chain of Writers and OutputStreams. | |
| 303 | + * | |
| 304 | + * <p> If the intended destination of this stream is an abstraction provided | |
| 305 | + * by the underlying operating system, for example a file, then flushing the | |
| 306 | + * stream guarantees only that bytes previously written to the stream are | |
| 307 | + * passed to the operating system for writing; it does not guarantee that | |
| 308 | + * they are actually written to a physical device such as a disk drive. | |
| 309 | + * | |
| 310 | + * @throws IOException | |
| 311 | + * If an I/O error occurs | |
| 312 | + */ | |
| 313 | + abstract public void flush() throws IOException; | |
| 314 | + | |
| 315 | + /** | |
| 316 | + * Closes the stream, flushing it first. Once the stream has been closed, | |
| 317 | + * further write() or flush() invocations will cause an IOException to be | |
| 318 | + * thrown. Closing a previously closed stream has no effect. | |
| 319 | + * | |
| 320 | + * @throws IOException | |
| 321 | + * If an I/O error occurs | |
| 322 | + */ | |
| 323 | + abstract public void close() throws IOException; | |
| 324 | + | |
| 325 | +} | |