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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 | } | ||