libjava/classpath/java/io/OutputStreamWriter.java

   1 /* OutputStreamWriter.java -- Writer that converts chars to bytes
   2    Copyright (C) 1998, 1999, 2000, 2001, 2003, 2005  Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package java.io;
  40
  41 import gnu.java.nio.charset.EncodingHelper;
  42
  43 import java.nio.ByteBuffer;
  44 import java.nio.CharBuffer;
  45 import java.nio.charset.CharacterCodingException;
  46 import java.nio.charset.Charset;
  47 import java.nio.charset.CharsetEncoder;
  48 import java.nio.charset.CodingErrorAction;
  49 import java.nio.charset.MalformedInputException;
  50
  51 /**
  52  * This class writes characters to an output stream that is byte oriented
  53  * It converts the chars that are written to bytes using an encoding layer,
  54  * which is specific to a particular encoding standard.  The desired
  55  * encoding can either be specified by name, or if no encoding is specified,
  56  * the system default encoding will be used.  The system default encoding
  57  * name is determined from the system property <code>file.encoding</code>.
  58  * The only encodings that are guaranteed to be available are "8859_1"
  59  * (the Latin-1 character set) and "UTF8".  Unfortunately, Java does not
  60  * provide a mechanism for listing the encodings that are supported in
  61  * a given implementation.
  62  * <p>
  63  * Here is a list of standard encoding names that may be available:
  64  * <p>
  65  * <ul>
  66  * <li>8859_1 (ISO-8859-1/Latin-1)
  67  * <li>8859_2 (ISO-8859-2/Latin-2)
  68  * <li>8859_3 (ISO-8859-3/Latin-3)
  69  * <li>8859_4 (ISO-8859-4/Latin-4)
  70  * <li>8859_5 (ISO-8859-5/Latin-5)
  71  * <li>8859_6 (ISO-8859-6/Latin-6)
  72  * <li>8859_7 (ISO-8859-7/Latin-7)
  73  * <li>8859_8 (ISO-8859-8/Latin-8)
  74  * <li>8859_9 (ISO-8859-9/Latin-9)
  75  * <li>ASCII (7-bit ASCII)
  76  * <li>UTF8 (UCS Transformation Format-8)
  77  * <li>More Later
  78  * </ul>
  79  *
  80  * @author Aaron M. Renn (arenn@urbanophile.com)
  81  * @author Per Bothner (bothner@cygnus.com)
  82  * @date April 17, 1998.
  83  */
  84 public class OutputStreamWriter extends Writer
  85 {
  86   /**
  87    * The output stream.
  88    */
  89   private OutputStream out;
  90
  91   /**
  92    * The charset encoder.
  93    */
  94   private CharsetEncoder encoder;
  95
  96   /**
  97    * java.io canonical name of the encoding.
  98    */
  99   private String encodingName;
 100
 101   /**
 102    * Buffer output before character conversion as it has costly overhead.
 103    */
 104   private CharBuffer outputBuffer;
 105   private final static int BUFFER_SIZE = 1024;
 106
 107   /**
 108    * This method initializes a new instance of <code>OutputStreamWriter</code>
 109    * to write to the specified stream using a caller supplied character
 110    * encoding scheme.  Note that due to a deficiency in the Java language
 111    * design, there is no way to determine which encodings are supported.
 112    *
 113    * @param out The <code>OutputStream</code> to write to
 114    * @param encoding_scheme The name of the encoding scheme to use for
 115    * character to byte translation
 116    *
 117    * @exception UnsupportedEncodingException If the named encoding is
 118    * not available.
 119    */
 120   public OutputStreamWriter (OutputStream out, String encoding_scheme)
 121     throws UnsupportedEncodingException
 122   {
 123     this.out = out;
 124     try
 125       {
 126         // Don't use NIO if avoidable
 127         if(EncodingHelper.isISOLatin1(encoding_scheme))
 128           {
 129             encodingName = "ISO8859_1";
 130             encoder = null;
 131             return;
 132           }
 133
 134         /*
 135          * Workraround for encodings with a byte-order-mark.
 136          * We only want to write it once per stream.
 137          */
 138         try
 139           {
 140             if(encoding_scheme.equalsIgnoreCase("UnicodeBig") ||
 141                encoding_scheme.equalsIgnoreCase("UTF-16") ||
 142                encoding_scheme.equalsIgnoreCase("UTF16"))
 143               {
 144                 encoding_scheme = "UTF-16BE";
 145                 out.write((byte)0xFE);
 146                 out.write((byte)0xFF);
 147               }
 148             else if(encoding_scheme.equalsIgnoreCase("UnicodeLittle")){
 149               encoding_scheme = "UTF-16LE";
 150               out.write((byte)0xFF);
 151               out.write((byte)0xFE);
 152             }
 153           }
 154         catch(IOException ioe)
 155           {
 156           }
 157
 158         outputBuffer = CharBuffer.allocate(BUFFER_SIZE);
 159
 160         Charset cs = EncodingHelper.getCharset(encoding_scheme);
 161         if(cs == null)
 162           throw new UnsupportedEncodingException("Encoding "+encoding_scheme+
 163                                                  " unknown");
 164         encoder = cs.newEncoder();
 165         encodingName = EncodingHelper.getOldCanonical(cs.name());
 166
 167         encoder.onMalformedInput(CodingErrorAction.REPLACE);
 168         encoder.onUnmappableCharacter(CodingErrorAction.REPLACE);
 169       }
 170     catch(RuntimeException e)
 171       {
 172         // Default to ISO Latin-1, will happen if this is called, for instance,
 173         //  before the NIO provider is loadable.
 174         encoder = null;
 175         encodingName = "ISO8859_1";
 176       }
 177   }
 178
 179   /**
 180    * This method initializes a new instance of <code>OutputStreamWriter</code>
 181    * to write to the specified stream using the default encoding.
 182    *
 183    * @param out The <code>OutputStream</code> to write to
 184    */
 185   public OutputStreamWriter (OutputStream out)
 186   {
 187     this.out = out;
 188     outputBuffer = null;
 189     try
 190       {
 191         String encoding = System.getProperty("file.encoding");
 192         Charset cs = Charset.forName(encoding);
 193         encoder = cs.newEncoder();
 194         encodingName =  EncodingHelper.getOldCanonical(cs.name());
 195       }
 196     catch(RuntimeException e)
 197       {
 198         encoder = null;
 199         encodingName = "ISO8859_1";
 200       }
 201
 202     if(encoder != null)
 203       {
 204         encoder.onMalformedInput(CodingErrorAction.REPLACE);
 205         encoder.onUnmappableCharacter(CodingErrorAction.REPLACE);
 206         outputBuffer = CharBuffer.allocate(BUFFER_SIZE);
 207       }
 208   }
 209
 210   /**
 211    * This method initializes a new instance of <code>OutputStreamWriter</code>
 212    * to write to the specified stream using a given <code>Charset</code>.
 213    *
 214    * @param out The <code>OutputStream</code> to write to
 215    * @param cs The <code>Charset</code> of the encoding to use
 216    *
 217    * @since 1.5
 218    */
 219   public OutputStreamWriter(OutputStream out, Charset cs)
 220   {
 221     this.out = out;
 222     encoder = cs.newEncoder();
 223     encoder.onMalformedInput(CodingErrorAction.REPLACE);
 224     encoder.onUnmappableCharacter(CodingErrorAction.REPLACE);
 225     outputBuffer = CharBuffer.allocate(BUFFER_SIZE);
 226   }
 227
 228   /**
 229    * This method initializes a new instance of <code>OutputStreamWriter</code>
 230    * to write to the specified stream using a given
 231    * <code>CharsetEncoder</code>.
 232    *
 233    * @param out The <code>OutputStream</code> to write to
 234    * @param enc The <code>CharsetEncoder</code> to encode the output with
 235    *
 236    * @since 1.5
 237    */
 238   public OutputStreamWriter(OutputStream out, CharsetEncoder enc)
 239   {
 240     this.out = out;
 241     encoder = enc;
 242     outputBuffer = CharBuffer.allocate(BUFFER_SIZE);
 243   }
 244
 245   /**
 246    * This method closes this stream, and the underlying
 247    * <code>OutputStream</code>
 248    *
 249    * @exception IOException If an error occurs
 250    */
 251   public void close () throws IOException
 252   {
 253     if(out == null)
 254       return;
 255     flush();
 256     out.close ();
 257     out = null;
 258   }
 259
 260   /**
 261    * This method returns the name of the character encoding scheme currently
 262    * in use by this stream.  If the stream has been closed, then this method
 263    * may return <code>null</code>.
 264    *
 265    * @return The encoding scheme name
 266    */
 267   public String getEncoding ()
 268   {
 269     return out != null ? encodingName : null;
 270   }
 271
 272   /**
 273    * This method flushes any buffered bytes to the underlying output sink.
 274    *
 275    * @exception IOException If an error occurs
 276    */
 277   public void flush () throws IOException
 278   {
 279       if(out != null){
 280           if(outputBuffer != null){
 281               char[] buf = new char[outputBuffer.position()];
 282               if(buf.length > 0){
 283                   outputBuffer.flip();
 284                   outputBuffer.get(buf);
 285                   writeConvert(buf, 0, buf.length);
 286                   outputBuffer.clear();
 287               }
 288           }
 289           out.flush ();
 290       }
 291   }
 292
 293   /**
 294    * This method writes <code>count</code> characters from the specified
 295    * array to the output stream starting at position <code>offset</code>
 296    * into the array.
 297    *
 298    * @param buf The array of character to write from
 299    * @param offset The offset into the array to start writing chars from
 300    * @param count The number of chars to write.
 301    *
 302    * @exception IOException If an error occurs
 303    */
 304   public void write (char[] buf, int offset, int count) throws IOException
 305   {
 306     if(out == null)
 307       throw new IOException("Stream is closed.");
 308     if(buf == null)
 309       throw new IOException("Buffer is null.");
 310
 311     if(outputBuffer != null)
 312         {
 313             if(count >= outputBuffer.remaining())
 314                 {
 315                     int r = outputBuffer.remaining();
 316                     outputBuffer.put(buf, offset, r);
 317                     writeConvert(outputBuffer.array(), 0, BUFFER_SIZE);
 318                     outputBuffer.clear();
 319                     offset += r;
 320                     count -= r;
 321                     // if the remaining bytes is larger than the whole buffer,
 322                     // just don't buffer.
 323                     if(count >= outputBuffer.remaining()){
 324                       writeConvert(buf, offset, count);
 325                       return;
 326                     }
 327                 }
 328             outputBuffer.put(buf, offset, count);
 329         } else writeConvert(buf, offset, count);
 330   }
 331
 332  /**
 333   * Converts and writes characters.
 334   */
 335   private void writeConvert (char[] buf, int offset, int count)
 336       throws IOException
 337   {
 338     if(encoder == null)
 339     {
 340       byte[] b = new byte[count];
 341       for(int i=0;i<count;i++)
 342         b[i] = (byte)((buf[offset+i] <= 0xFF)?buf[offset+i]:'?');
 343       out.write(b);
 344     } else {
 345       try  {
 346         ByteBuffer output = encoder.encode(CharBuffer.wrap(buf,offset,count));
 347         encoder.reset();
 348         if(output.hasArray())
 349           out.write(output.array());
 350         else
 351           {
 352             byte[] outbytes = new byte[output.remaining()];
 353             output.get(outbytes);
 354             out.write(outbytes);
 355           }
 356       } catch(IllegalStateException e) {
 357         throw new IOException("Internal error.");
 358       } catch(MalformedInputException e) {
 359         throw new IOException("Invalid character sequence.");
 360       } catch(CharacterCodingException e) {
 361         throw new IOException("Unmappable character.");
 362       }
 363     }
 364   }
 365
 366   /**
 367    * This method writes <code>count</code> bytes from the specified
 368    * <code>String</code> starting at position <code>offset</code> into the
 369    * <code>String</code>.
 370    *
 371    * @param str The <code>String</code> to write chars from
 372    * @param offset The position in the <code>String</code> to start
 373    * writing chars from
 374    * @param count The number of chars to write
 375    *
 376    * @exception IOException If an error occurs
 377    */
 378   public void write (String str, int offset, int count) throws IOException
 379   {
 380     if(str == null)
 381       throw new IOException("String is null.");
 382
 383     write(str.toCharArray(), offset, count);
 384   }
 385
 386   /**
 387    * This method writes a single character to the output stream.
 388    *
 389    * @param ch The char to write, passed as an int.
 390    *
 391    * @exception IOException If an error occurs
 392    */
 393   public void write (int ch) throws IOException
 394   {
 395     write(new char[]{ (char)ch }, 0, 1);
 396   }
 397 } // class OutputStreamWriter
 398