001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.commons.io.output; 018 019import java.io.IOException; 020import java.io.OutputStream; 021import java.io.Writer; 022import java.nio.ByteBuffer; 023import java.nio.CharBuffer; 024import java.nio.charset.Charset; 025import java.nio.charset.CharsetDecoder; 026import java.nio.charset.CoderResult; 027import java.nio.charset.CodingErrorAction; 028import java.nio.charset.StandardCharsets; 029 030import org.apache.commons.io.Charsets; 031import org.apache.commons.io.IOUtils; 032import org.apache.commons.io.build.AbstractStreamBuilder; 033import org.apache.commons.io.charset.CharsetDecoders; 034 035/** 036 * {@link OutputStream} implementation that transforms a byte stream to a character stream using a specified charset encoding and writes the resulting stream to 037 * a {@link Writer}. The stream is transformed using a {@link CharsetDecoder} object, guaranteeing that all charset encodings supported by the JRE are handled 038 * correctly. 039 * <p> 040 * The output of the {@link CharsetDecoder} is buffered using a fixed size buffer. This implies that the data is written to the underlying {@link Writer} in 041 * chunks that are no larger than the size of this buffer. By default, the buffer is flushed only when it overflows or when {@link #flush()} or {@link #close()} 042 * is called. In general there is therefore no need to wrap the underlying {@link Writer} in a {@link java.io.BufferedWriter}. {@link WriterOutputStream} can 043 * also be instructed to flush the buffer after each write operation. In this case, all available data is written immediately to the underlying {@link Writer}, 044 * implying that the current position of the {@link Writer} is correlated to the current position of the {@link WriterOutputStream}. 045 * </p> 046 * <p> 047 * {@link WriterOutputStream} implements the inverse transformation of {@link java.io.OutputStreamWriter}; in the following example, writing to {@code out2} 048 * would have the same result as writing to {@code out} directly (provided that the byte sequence is legal with respect to the charset encoding): 049 * </p> 050 * <p> 051 * To build an instance, see {@link Builder}. 052 * </p> 053 * <pre> 054 * OutputStream out = ... 055 * Charset cs = ... 056 * OutputStreamWriter writer = new OutputStreamWriter(out, cs); 057 * WriterOutputStream out2 = WriterOutputStream.builder() 058 * .setWriter(writer) 059 * .setCharset(cs) 060 * .get(); 061 * </pre> 062 * <p> 063 * {@link WriterOutputStream} implements the same transformation as {@link java.io.InputStreamReader}, except that the control flow is reversed: both classes 064 * transform a byte stream into a character stream, but {@link java.io.InputStreamReader} pulls data from the underlying stream, while 065 * {@link WriterOutputStream} pushes it to the underlying stream. 066 * </p> 067 * <p> 068 * Note that while there are use cases where there is no alternative to using this class, very often the need to use this class is an indication of a flaw in 069 * the design of the code. This class is typically used in situations where an existing API only accepts an {@link OutputStream} object, but where the stream is 070 * known to represent character data that must be decoded for further use. 071 * </p> 072 * <p> 073 * Instances of {@link WriterOutputStream} are not thread safe. 074 * </p> 075 * 076 * @see org.apache.commons.io.input.ReaderInputStream 077 * @since 2.0 078 */ 079public class WriterOutputStream extends OutputStream { 080 081 /** 082 * Builds a new {@link WriterOutputStream} instance. 083 * <p> 084 * For example: 085 * </p> 086 * <pre>{@code 087 * WriterOutputStream s = WriterOutputStream.builder() 088 * .setPath(path) 089 * .setBufferSize(8192) 090 * .setCharset(StandardCharsets.UTF_8) 091 * .setWriteImmediately(false) 092 * .get();} 093 * </pre> 094 * 095 * @since 2.12.0 096 */ 097 public static class Builder extends AbstractStreamBuilder<WriterOutputStream, Builder> { 098 099 private CharsetDecoder charsetDecoder; 100 private boolean writeImmediately; 101 102 public Builder() { 103 this.charsetDecoder = getCharset().newDecoder(); 104 } 105 106 /** 107 * Constructs a new instance. 108 * <p> 109 * This builder use the aspect Writer, OpenOption[], Charset, CharsetDecoder, buffer size and writeImmediately. 110 * </p> 111 * <p> 112 * You must provide an origin that can be converted to a Writer by this builder, otherwise, this call will throw an 113 * {@link UnsupportedOperationException}. 114 * </p> 115 * 116 * @return a new instance. 117 * @throws UnsupportedOperationException if the origin cannot provide a Writer. 118 * @see #getWriter() 119 */ 120 @SuppressWarnings("resource") 121 @Override 122 public WriterOutputStream get() throws IOException { 123 return new WriterOutputStream(getWriter(), charsetDecoder, getBufferSize(), writeImmediately); 124 } 125 126 @Override 127 public Builder setCharset(final Charset charset) { 128 super.setCharset(charset); 129 this.charsetDecoder = getCharset().newDecoder(); 130 return this; 131 } 132 133 @Override 134 public Builder setCharset(final String charset) { 135 super.setCharset(charset); 136 this.charsetDecoder = getCharset().newDecoder(); 137 return this; 138 } 139 140 /** 141 * Sets the charset decoder. 142 * 143 * @param charsetDecoder the charset decoder. 144 * @return this 145 */ 146 public Builder setCharsetDecoder(final CharsetDecoder charsetDecoder) { 147 this.charsetDecoder = charsetDecoder != null ? charsetDecoder : getCharsetDefault().newDecoder(); 148 super.setCharset(this.charsetDecoder.charset()); 149 return this; 150 } 151 152 /** 153 * Sets whether the output buffer will be flushed after each write operation ({@code true}), i.e. all available data will be written to the underlying 154 * {@link Writer} immediately. If {@code false}, the output buffer will only be flushed when it overflows or when {@link #flush()} or {@link #close()} 155 * is called. 156 * 157 * @param writeImmediately If {@code true} the output buffer will be flushed after each write operation, i.e. all available data will be written to the 158 * underlying {@link Writer} immediately. If {@code false}, the output buffer will only be flushed when it overflows or when 159 * {@link #flush()} or {@link #close()} is called. 160 * @return this 161 */ 162 public Builder setWriteImmediately(final boolean writeImmediately) { 163 this.writeImmediately = writeImmediately; 164 return this; 165 } 166 167 } 168 169 private static final int BUFFER_SIZE = IOUtils.DEFAULT_BUFFER_SIZE; 170 171 /** 172 * Constructs a new {@link Builder}. 173 * 174 * @return a new {@link Builder}. 175 * @since 2.12.0 176 */ 177 public static Builder builder() { 178 return new Builder(); 179 } 180 181 /** 182 * Checks if the JDK in use properly supports the given charset. 183 * 184 * @param charset the charset to check the support for 185 */ 186 private static void checkIbmJdkWithBrokenUTF16(final Charset charset) { 187 if (!StandardCharsets.UTF_16.name().equals(charset.name())) { 188 return; 189 } 190 final String TEST_STRING_2 = "v\u00e9s"; 191 final byte[] bytes = TEST_STRING_2.getBytes(charset); 192 193 final CharsetDecoder charsetDecoder2 = charset.newDecoder(); 194 final ByteBuffer bb2 = ByteBuffer.allocate(16); 195 final CharBuffer cb2 = CharBuffer.allocate(TEST_STRING_2.length()); 196 final int len = bytes.length; 197 for (int i = 0; i < len; i++) { 198 bb2.put(bytes[i]); 199 bb2.flip(); 200 try { 201 charsetDecoder2.decode(bb2, cb2, i == len - 1); 202 } catch (final IllegalArgumentException e) { 203 throw new UnsupportedOperationException("UTF-16 requested when running on an IBM JDK with broken UTF-16 support. " 204 + "Please find a JDK that supports UTF-16 if you intend to use UF-16 with WriterOutputStream"); 205 } 206 bb2.compact(); 207 } 208 cb2.rewind(); 209 if (!TEST_STRING_2.equals(cb2.toString())) { 210 throw new UnsupportedOperationException("UTF-16 requested when running on an IBM JDK with broken UTF-16 support. " 211 + "Please find a JDK that supports UTF-16 if you intend to use UF-16 with WriterOutputStream"); 212 } 213 214 } 215 216 private final Writer writer; 217 private final CharsetDecoder decoder; 218 219 private final boolean writeImmediately; 220 221 /** 222 * ByteBuffer used as input for the decoder. This buffer can be small as it is used only to transfer the received data to the decoder. 223 */ 224 private final ByteBuffer decoderIn = ByteBuffer.allocate(128); 225 226 /** 227 * CharBuffer used as output for the decoder. It should be somewhat larger as we write from this buffer to the underlying Writer. 228 */ 229 private final CharBuffer decoderOut; 230 231 /** 232 * Constructs a new {@link WriterOutputStream} that uses the default character encoding and with a default output buffer size of {@value #BUFFER_SIZE} 233 * characters. The output buffer will only be flushed when it overflows or when {@link #flush()} or {@link #close()} is called. 234 * 235 * @param writer the target {@link Writer} 236 * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()} 237 */ 238 @Deprecated 239 public WriterOutputStream(final Writer writer) { 240 this(writer, Charset.defaultCharset(), BUFFER_SIZE, false); 241 } 242 243 /** 244 * Constructs a new {@link WriterOutputStream} with a default output buffer size of {@value #BUFFER_SIZE} characters. The output buffer will only be flushed 245 * when it overflows or when {@link #flush()} or {@link #close()} is called. 246 * 247 * @param writer the target {@link Writer} 248 * @param charset the charset encoding 249 * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()} 250 */ 251 @Deprecated 252 public WriterOutputStream(final Writer writer, final Charset charset) { 253 this(writer, charset, BUFFER_SIZE, false); 254 } 255 256 /** 257 * Constructs a new {@link WriterOutputStream}. 258 * 259 * @param writer the target {@link Writer} 260 * @param charset the charset encoding 261 * @param bufferSize the size of the output buffer in number of characters 262 * @param writeImmediately If {@code true} the output buffer will be flushed after each write operation, i.e. all available data will be written to the 263 * underlying {@link Writer} immediately. If {@code false}, the output buffer will only be flushed when it overflows or when 264 * {@link #flush()} or {@link #close()} is called. 265 * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()} 266 */ 267 @Deprecated 268 public WriterOutputStream(final Writer writer, final Charset charset, final int bufferSize, final boolean writeImmediately) { 269 // @formatter:off 270 this(writer, 271 Charsets.toCharset(charset).newDecoder() 272 .onMalformedInput(CodingErrorAction.REPLACE) 273 .onUnmappableCharacter(CodingErrorAction.REPLACE) 274 .replaceWith("?"), 275 bufferSize, 276 writeImmediately); 277 // @formatter:on 278 } 279 280 /** 281 * Constructs a new {@link WriterOutputStream} with a default output buffer size of {@value #BUFFER_SIZE} characters. The output buffer will only be flushed 282 * when it overflows or when {@link #flush()} or {@link #close()} is called. 283 * 284 * @param writer the target {@link Writer} 285 * @param decoder the charset decoder 286 * @since 2.1 287 * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()} 288 */ 289 @Deprecated 290 public WriterOutputStream(final Writer writer, final CharsetDecoder decoder) { 291 this(writer, decoder, BUFFER_SIZE, false); 292 } 293 294 /** 295 * Constructs a new {@link WriterOutputStream}. 296 * 297 * @param writer the target {@link Writer} 298 * @param decoder the charset decoder 299 * @param bufferSize the size of the output buffer in number of characters 300 * @param writeImmediately If {@code true} the output buffer will be flushed after each write operation, i.e. all available data will be written to the 301 * underlying {@link Writer} immediately. If {@code false}, the output buffer will only be flushed when it overflows or when 302 * {@link #flush()} or {@link #close()} is called. 303 * @since 2.1 304 * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()} 305 */ 306 @Deprecated 307 public WriterOutputStream(final Writer writer, final CharsetDecoder decoder, final int bufferSize, final boolean writeImmediately) { 308 checkIbmJdkWithBrokenUTF16(CharsetDecoders.toCharsetDecoder(decoder).charset()); 309 this.writer = writer; 310 this.decoder = CharsetDecoders.toCharsetDecoder(decoder); 311 this.writeImmediately = writeImmediately; 312 this.decoderOut = CharBuffer.allocate(bufferSize); 313 } 314 315 /** 316 * Constructs a new {@link WriterOutputStream} with a default output buffer size of {@value #BUFFER_SIZE} characters. The output buffer will only be flushed 317 * when it overflows or when {@link #flush()} or {@link #close()} is called. 318 * 319 * @param writer the target {@link Writer} 320 * @param charsetName the name of the charset encoding 321 * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()} 322 */ 323 @Deprecated 324 public WriterOutputStream(final Writer writer, final String charsetName) { 325 this(writer, charsetName, BUFFER_SIZE, false); 326 } 327 328 /** 329 * Constructs a new {@link WriterOutputStream}. 330 * 331 * @param writer the target {@link Writer} 332 * @param charsetName the name of the charset encoding 333 * @param bufferSize the size of the output buffer in number of characters 334 * @param writeImmediately If {@code true} the output buffer will be flushed after each write operation, i.e. all available data will be written to the 335 * underlying {@link Writer} immediately. If {@code false}, the output buffer will only be flushed when it overflows or when 336 * {@link #flush()} or {@link #close()} is called. 337 * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()} 338 */ 339 @Deprecated 340 public WriterOutputStream(final Writer writer, final String charsetName, final int bufferSize, final boolean writeImmediately) { 341 this(writer, Charsets.toCharset(charsetName), bufferSize, writeImmediately); 342 } 343 344 /** 345 * Close the stream. Any remaining content accumulated in the output buffer will be written to the underlying {@link Writer}. After that 346 * {@link Writer#close()} will be called. 347 * 348 * @throws IOException if an I/O error occurs. 349 */ 350 @Override 351 public void close() throws IOException { 352 processInput(true); 353 flushOutput(); 354 writer.close(); 355 } 356 357 /** 358 * Flush the stream. Any remaining content accumulated in the output buffer will be written to the underlying {@link Writer}. After that 359 * {@link Writer#flush()} will be called. 360 * 361 * @throws IOException if an I/O error occurs. 362 */ 363 @Override 364 public void flush() throws IOException { 365 flushOutput(); 366 writer.flush(); 367 } 368 369 /** 370 * Flush the output. 371 * 372 * @throws IOException if an I/O error occurs. 373 */ 374 private void flushOutput() throws IOException { 375 if (decoderOut.position() > 0) { 376 writer.write(decoderOut.array(), 0, decoderOut.position()); 377 decoderOut.rewind(); 378 } 379 } 380 381 /** 382 * Decode the contents of the input ByteBuffer into a CharBuffer. 383 * 384 * @param endOfInput indicates end of input 385 * @throws IOException if an I/O error occurs. 386 */ 387 private void processInput(final boolean endOfInput) throws IOException { 388 // Prepare decoderIn for reading 389 decoderIn.flip(); 390 CoderResult coderResult; 391 while (true) { 392 coderResult = decoder.decode(decoderIn, decoderOut, endOfInput); 393 if (coderResult.isOverflow()) { 394 flushOutput(); 395 } else if (coderResult.isUnderflow()) { 396 break; 397 } else { 398 // The decoder is configured to replace malformed input and unmappable characters, 399 // so we should not get here. 400 throw new IOException("Unexpected coder result"); 401 } 402 } 403 // Discard the bytes that have been read 404 decoderIn.compact(); 405 } 406 407 /** 408 * Write bytes from the specified byte array to the stream. 409 * 410 * @param b the byte array containing the bytes to write 411 * @throws IOException if an I/O error occurs. 412 */ 413 @Override 414 public void write(final byte[] b) throws IOException { 415 write(b, 0, b.length); 416 } 417 418 /** 419 * Write bytes from the specified byte array to the stream. 420 * 421 * @param b the byte array containing the bytes to write 422 * @param off the start offset in the byte array 423 * @param len the number of bytes to write 424 * @throws IOException if an I/O error occurs. 425 */ 426 @Override 427 public void write(final byte[] b, int off, int len) throws IOException { 428 while (len > 0) { 429 final int c = Math.min(len, decoderIn.remaining()); 430 decoderIn.put(b, off, c); 431 processInput(false); 432 len -= c; 433 off += c; 434 } 435 if (writeImmediately) { 436 flushOutput(); 437 } 438 } 439 440 /** 441 * Write a single byte to the stream. 442 * 443 * @param b the byte to write 444 * @throws IOException if an I/O error occurs. 445 */ 446 @Override 447 public void write(final int b) throws IOException { 448 write(new byte[] { (byte) b }, 0, 1); 449 } 450}