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| 1 | +/* | |
| 2 | + * Copyright (c) 1995, 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 sun.misc; | |
| 27 | + | |
| 28 | +import java.io.InputStream; | |
| 29 | +import java.io.ByteArrayInputStream; | |
| 30 | +import java.io.OutputStream; | |
| 31 | +import java.io.ByteArrayOutputStream; | |
| 32 | +import java.io.PrintStream; | |
| 33 | +import java.io.IOException; | |
| 34 | +import java.nio.ByteBuffer; | |
| 35 | + | |
| 36 | + | |
| 37 | +/** | |
| 38 | + * This class defines the encoding half of character encoders. | |
| 39 | + * A character encoder is an algorithim for transforming 8 bit binary | |
| 40 | + * data into text (generally 7 bit ASCII or 8 bit ISO-Latin-1 text) | |
| 41 | + * for transmition over text channels such as e-mail and network news. | |
| 42 | + * | |
| 43 | + * The character encoders have been structured around a central theme | |
| 44 | + * that, in general, the encoded text has the form: | |
| 45 | + * | |
| 46 | + * <pre> | |
| 47 | + * [Buffer Prefix] | |
| 48 | + * [Line Prefix][encoded data atoms][Line Suffix] | |
| 49 | + * [Buffer Suffix] | |
| 50 | + * </pre> | |
| 51 | + * | |
| 52 | + * In the CharacterEncoder and CharacterDecoder classes, one complete | |
| 53 | + * chunk of data is referred to as a <i>buffer</i>. Encoded buffers | |
| 54 | + * are all text, and decoded buffers (sometimes just referred to as | |
| 55 | + * buffers) are binary octets. | |
| 56 | + * | |
| 57 | + * To create a custom encoder, you must, at a minimum, overide three | |
| 58 | + * abstract methods in this class. | |
| 59 | + * <DL> | |
| 60 | + * <DD>bytesPerAtom which tells the encoder how many bytes to | |
| 61 | + * send to encodeAtom | |
| 62 | + * <DD>encodeAtom which encodes the bytes sent to it as text. | |
| 63 | + * <DD>bytesPerLine which tells the encoder the maximum number of | |
| 64 | + * bytes per line. | |
| 65 | + * </DL> | |
| 66 | + * | |
| 67 | + * Several useful encoders have already been written and are | |
| 68 | + * referenced in the See Also list below. | |
| 69 | + * | |
| 70 | + * @author Chuck McManis | |
| 71 | + * @see CharacterDecoder; | |
| 72 | + * @see UCEncoder | |
| 73 | + * @see UUEncoder | |
| 74 | + * @see BASE64Encoder | |
| 75 | + */ | |
| 76 | +public abstract class CharacterEncoder { | |
| 77 | + | |
| 78 | + /** Stream that understands "printing" */ | |
| 79 | + protected PrintStream pStream; | |
| 80 | + | |
| 81 | + /** Return the number of bytes per atom of encoding */ | |
| 82 | + abstract protected int bytesPerAtom(); | |
| 83 | + | |
| 84 | + /** Return the number of bytes that can be encoded per line */ | |
| 85 | + abstract protected int bytesPerLine(); | |
| 86 | + | |
| 87 | + /** | |
| 88 | + * Encode the prefix for the entire buffer. By default is simply | |
| 89 | + * opens the PrintStream for use by the other functions. | |
| 90 | + */ | |
| 91 | + protected void encodeBufferPrefix(OutputStream aStream) throws IOException { | |
| 92 | + pStream = new PrintStream(aStream); | |
| 93 | + } | |
| 94 | + | |
| 95 | + /** | |
| 96 | + * Encode the suffix for the entire buffer. | |
| 97 | + */ | |
| 98 | + protected void encodeBufferSuffix(OutputStream aStream) throws IOException { | |
| 99 | + } | |
| 100 | + | |
| 101 | + /** | |
| 102 | + * Encode the prefix that starts every output line. | |
| 103 | + */ | |
| 104 | + protected void encodeLinePrefix(OutputStream aStream, int aLength) | |
| 105 | + throws IOException { | |
| 106 | + } | |
| 107 | + | |
| 108 | + /** | |
| 109 | + * Encode the suffix that ends every output line. By default | |
| 110 | + * this method just prints a <newline> into the output stream. | |
| 111 | + */ | |
| 112 | + protected void encodeLineSuffix(OutputStream aStream) throws IOException { | |
| 113 | + pStream.println(); | |
| 114 | + } | |
| 115 | + | |
| 116 | + /** Encode one "atom" of information into characters. */ | |
| 117 | + abstract protected void encodeAtom(OutputStream aStream, byte someBytes[], | |
| 118 | + int anOffset, int aLength) throws IOException; | |
| 119 | + | |
| 120 | + /** | |
| 121 | + * This method works around the bizarre semantics of BufferedInputStream's | |
| 122 | + * read method. | |
| 123 | + */ | |
| 124 | + protected int readFully(InputStream in, byte buffer[]) | |
| 125 | + throws java.io.IOException { | |
| 126 | + for (int i = 0; i < buffer.length; i++) { | |
| 127 | + int q = in.read(); | |
| 128 | + if (q == -1) | |
| 129 | + return i; | |
| 130 | + buffer[i] = (byte)q; | |
| 131 | + } | |
| 132 | + return buffer.length; | |
| 133 | + } | |
| 134 | + | |
| 135 | + /** | |
| 136 | + * Encode bytes from the input stream, and write them as text characters | |
| 137 | + * to the output stream. This method will run until it exhausts the | |
| 138 | + * input stream, but does not print the line suffix for a final | |
| 139 | + * line that is shorter than bytesPerLine(). | |
| 140 | + */ | |
| 141 | + public void encode(InputStream inStream, OutputStream outStream) | |
| 142 | + throws IOException { | |
| 143 | + int j; | |
| 144 | + int numBytes; | |
| 145 | + byte tmpbuffer[] = new byte[bytesPerLine()]; | |
| 146 | + | |
| 147 | + encodeBufferPrefix(outStream); | |
| 148 | + | |
| 149 | + while (true) { | |
| 150 | + numBytes = readFully(inStream, tmpbuffer); | |
| 151 | + if (numBytes == 0) { | |
| 152 | + break; | |
| 153 | + } | |
| 154 | + encodeLinePrefix(outStream, numBytes); | |
| 155 | + for (j = 0; j < numBytes; j += bytesPerAtom()) { | |
| 156 | + | |
| 157 | + if ((j + bytesPerAtom()) <= numBytes) { | |
| 158 | + encodeAtom(outStream, tmpbuffer, j, bytesPerAtom()); | |
| 159 | + } else { | |
| 160 | + encodeAtom(outStream, tmpbuffer, j, (numBytes)- j); | |
| 161 | + } | |
| 162 | + } | |
| 163 | + if (numBytes < bytesPerLine()) { | |
| 164 | + break; | |
| 165 | + } else { | |
| 166 | + encodeLineSuffix(outStream); | |
| 167 | + } | |
| 168 | + } | |
| 169 | + encodeBufferSuffix(outStream); | |
| 170 | + } | |
| 171 | + | |
| 172 | + /** | |
| 173 | + * Encode the buffer in <i>aBuffer</i> and write the encoded | |
| 174 | + * result to the OutputStream <i>aStream</i>. | |
| 175 | + */ | |
| 176 | + public void encode(byte aBuffer[], OutputStream aStream) | |
| 177 | + throws IOException { | |
| 178 | + ByteArrayInputStream inStream = new ByteArrayInputStream(aBuffer); | |
| 179 | + encode(inStream, aStream); | |
| 180 | + } | |
| 181 | + | |
| 182 | + /** | |
| 183 | + * A 'streamless' version of encode that simply takes a buffer of | |
| 184 | + * bytes and returns a string containing the encoded buffer. | |
| 185 | + */ | |
| 186 | + public String encode(byte aBuffer[]) { | |
| 187 | + ByteArrayOutputStream outStream = new ByteArrayOutputStream(); | |
| 188 | + ByteArrayInputStream inStream = new ByteArrayInputStream(aBuffer); | |
| 189 | + String retVal = null; | |
| 190 | + try { | |
| 191 | + encode(inStream, outStream); | |
| 192 | + // explicit ascii->unicode conversion | |
| 193 | + retVal = outStream.toString("8859_1"); | |
| 194 | + } catch (Exception IOException) { | |
| 195 | + // This should never happen. | |
| 196 | + throw new Error("CharacterEncoder.encode internal error"); | |
| 197 | + } | |
| 198 | + return (retVal); | |
| 199 | + } | |
| 200 | + | |
| 201 | + /** | |
| 202 | + * Return a byte array from the remaining bytes in this ByteBuffer. | |
| 203 | + * <P> | |
| 204 | + * The ByteBuffer's position will be advanced to ByteBuffer's limit. | |
| 205 | + * <P> | |
| 206 | + * To avoid an extra copy, the implementation will attempt to return the | |
| 207 | + * byte array backing the ByteBuffer. If this is not possible, a | |
| 208 | + * new byte array will be created. | |
| 209 | + */ | |
| 210 | + private byte [] getBytes(ByteBuffer bb) { | |
| 211 | + /* | |
| 212 | + * This should never return a BufferOverflowException, as we're | |
| 213 | + * careful to allocate just the right amount. | |
| 214 | + */ | |
| 215 | + byte [] buf = null; | |
| 216 | + | |
| 217 | + /* | |
| 218 | + * If it has a usable backing byte buffer, use it. Use only | |
| 219 | + * if the array exactly represents the current ByteBuffer. | |
| 220 | + */ | |
| 221 | + if (bb.hasArray()) { | |
| 222 | + byte [] tmp = bb.array(); | |
| 223 | + if ((tmp.length == bb.capacity()) && | |
| 224 | + (tmp.length == bb.remaining())) { | |
| 225 | + buf = tmp; | |
| 226 | + bb.position(bb.limit()); | |
| 227 | + } | |
| 228 | + } | |
| 229 | + | |
| 230 | + if (buf == null) { | |
| 231 | + /* | |
| 232 | + * This class doesn't have a concept of encode(buf, len, off), | |
| 233 | + * so if we have a partial buffer, we must reallocate | |
| 234 | + * space. | |
| 235 | + */ | |
| 236 | + buf = new byte[bb.remaining()]; | |
| 237 | + | |
| 238 | + /* | |
| 239 | + * position() automatically updated | |
| 240 | + */ | |
| 241 | + bb.get(buf); | |
| 242 | + } | |
| 243 | + | |
| 244 | + return buf; | |
| 245 | + } | |
| 246 | + | |
| 247 | + /** | |
| 248 | + * Encode the <i>aBuffer</i> ByteBuffer and write the encoded | |
| 249 | + * result to the OutputStream <i>aStream</i>. | |
| 250 | + * <P> | |
| 251 | + * The ByteBuffer's position will be advanced to ByteBuffer's limit. | |
| 252 | + */ | |
| 253 | + public void encode(ByteBuffer aBuffer, OutputStream aStream) | |
| 254 | + throws IOException { | |
| 255 | + byte [] buf = getBytes(aBuffer); | |
| 256 | + encode(buf, aStream); | |
| 257 | + } | |
| 258 | + | |
| 259 | + /** | |
| 260 | + * A 'streamless' version of encode that simply takes a ByteBuffer | |
| 261 | + * and returns a string containing the encoded buffer. | |
| 262 | + * <P> | |
| 263 | + * The ByteBuffer's position will be advanced to ByteBuffer's limit. | |
| 264 | + */ | |
| 265 | + public String encode(ByteBuffer aBuffer) { | |
| 266 | + byte [] buf = getBytes(aBuffer); | |
| 267 | + return encode(buf); | |
| 268 | + } | |
| 269 | + | |
| 270 | + /** | |
| 271 | + * Encode bytes from the input stream, and write them as text characters | |
| 272 | + * to the output stream. This method will run until it exhausts the | |
| 273 | + * input stream. It differs from encode in that it will add the | |
| 274 | + * line at the end of a final line that is shorter than bytesPerLine(). | |
| 275 | + */ | |
| 276 | + public void encodeBuffer(InputStream inStream, OutputStream outStream) | |
| 277 | + throws IOException { | |
| 278 | + int j; | |
| 279 | + int numBytes; | |
| 280 | + byte tmpbuffer[] = new byte[bytesPerLine()]; | |
| 281 | + | |
| 282 | + encodeBufferPrefix(outStream); | |
| 283 | + | |
| 284 | + while (true) { | |
| 285 | + numBytes = readFully(inStream, tmpbuffer); | |
| 286 | + if (numBytes == 0) { | |
| 287 | + break; | |
| 288 | + } | |
| 289 | + encodeLinePrefix(outStream, numBytes); | |
| 290 | + for (j = 0; j < numBytes; j += bytesPerAtom()) { | |
| 291 | + if ((j + bytesPerAtom()) <= numBytes) { | |
| 292 | + encodeAtom(outStream, tmpbuffer, j, bytesPerAtom()); | |
| 293 | + } else { | |
| 294 | + encodeAtom(outStream, tmpbuffer, j, (numBytes)- j); | |
| 295 | + } | |
| 296 | + } | |
| 297 | + encodeLineSuffix(outStream); | |
| 298 | + if (numBytes < bytesPerLine()) { | |
| 299 | + break; | |
| 300 | + } | |
| 301 | + } | |
| 302 | + encodeBufferSuffix(outStream); | |
| 303 | + } | |
| 304 | + | |
| 305 | + /** | |
| 306 | + * Encode the buffer in <i>aBuffer</i> and write the encoded | |
| 307 | + * result to the OutputStream <i>aStream</i>. | |
| 308 | + */ | |
| 309 | + public void encodeBuffer(byte aBuffer[], OutputStream aStream) | |
| 310 | + throws IOException { | |
| 311 | + ByteArrayInputStream inStream = new ByteArrayInputStream(aBuffer); | |
| 312 | + encodeBuffer(inStream, aStream); | |
| 313 | + } | |
| 314 | + | |
| 315 | + /** | |
| 316 | + * A 'streamless' version of encode that simply takes a buffer of | |
| 317 | + * bytes and returns a string containing the encoded buffer. | |
| 318 | + */ | |
| 319 | + public String encodeBuffer(byte aBuffer[]) { | |
| 320 | + ByteArrayOutputStream outStream = new ByteArrayOutputStream(); | |
| 321 | + ByteArrayInputStream inStream = new ByteArrayInputStream(aBuffer); | |
| 322 | + try { | |
| 323 | + encodeBuffer(inStream, outStream); | |
| 324 | + } catch (Exception IOException) { | |
| 325 | + // This should never happen. | |
| 326 | + throw new Error("CharacterEncoder.encodeBuffer internal error"); | |
| 327 | + } | |
| 328 | + return (outStream.toString()); | |
| 329 | + } | |
| 330 | + | |
| 331 | + /** | |
| 332 | + * Encode the <i>aBuffer</i> ByteBuffer and write the encoded | |
| 333 | + * result to the OutputStream <i>aStream</i>. | |
| 334 | + * <P> | |
| 335 | + * The ByteBuffer's position will be advanced to ByteBuffer's limit. | |
| 336 | + */ | |
| 337 | + public void encodeBuffer(ByteBuffer aBuffer, OutputStream aStream) | |
| 338 | + throws IOException { | |
| 339 | + byte [] buf = getBytes(aBuffer); | |
| 340 | + encodeBuffer(buf, aStream); | |
| 341 | + } | |
| 342 | + | |
| 343 | + /** | |
| 344 | + * A 'streamless' version of encode that simply takes a ByteBuffer | |
| 345 | + * and returns a string containing the encoded buffer. | |
| 346 | + * <P> | |
| 347 | + * The ByteBuffer's position will be advanced to ByteBuffer's limit. | |
| 348 | + */ | |
| 349 | + public String encodeBuffer(ByteBuffer aBuffer) { | |
| 350 | + byte [] buf = getBytes(aBuffer); | |
| 351 | + return encodeBuffer(buf); | |
| 352 | + } | |
| 353 | + | |
| 354 | +} | |