View Javadoc

    1   /*
    2    * $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//httpclient/src/java/org/apache/commons/httpclient/ChunkedOutputStream.java,v 1.16 2004/05/13 04:03:25 mbecke Exp $
    3    * $Revision: 480424 $
    4    * $Date: 2006-11-29 06:56:49 +0100 (Wed, 29 Nov 2006) $
    5    *
    6    * ====================================================================
    7    *
    8    *  Licensed to the Apache Software Foundation (ASF) under one or more
    9    *  contributor license agreements.  See the NOTICE file distributed with
    10   *  this work for additional information regarding copyright ownership.
    11   *  The ASF licenses this file to You under the Apache License, Version 2.0
    12   *  (the "License"); you may not use this file except in compliance with
    13   *  the License.  You may obtain a copy of the License at
    14   *
    15   *      http://www.apache.org/licenses/LICENSE-2.0
    16   *
    17   *  Unless required by applicable law or agreed to in writing, software
    18   *  distributed under the License is distributed on an "AS IS" BASIS,
    19   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    20   *  See the License for the specific language governing permissions and
    21   *  limitations under the License.
    22   * ====================================================================
    23   *
    24   * This software consists of voluntary contributions made by many
    25   * individuals on behalf of the Apache Software Foundation.  For more
    26   * information on the Apache Software Foundation, please see
    27   * <http://www.apache.org/>.
    28   *
    29   */
    30
    31  package org.apache.commons.httpclient;
    32
    33  import java.io.IOException;
    34  import java.io.OutputStream;
    35
    36  import org.apache.commons.httpclient.util.EncodingUtil;
    37
    38  /**
    39   * Implements HTTP chunking support. Writes are buffered to an internal buffer (2048 default size).
    40   * Chunks are guaranteed to be at least as large as the buffer size (except for the last chunk).
    41   *
    42   * @author Mohammad Rezaei, Goldman, Sachs & Co.
    43   */
    44  public class ChunkedOutputStream extends OutputStream {
    45
    46      // ------------------------------------------------------- Static Variables
    47      private static final byte CRLF[] = new byte[] {(byte) 13, (byte) 10};
    48
    49      /** End chunk */
    50      private static final byte ENDCHUNK[] = CRLF;
    51
    52      /** 0 */
    53      private static final byte ZERO[] = new byte[] {(byte) '0'};
    54
    55      // ----------------------------------------------------- Instance Variables
    56      private OutputStream stream = null;
    57
    58      private byte[] cache;
    59
    60      private int cachePosition = 0;
    61
    62      private boolean wroteLastChunk = false;
    63
    64      // ----------------------------------------------------------- Constructors
    65      /**
    66       * Wraps a stream and chunks the output.
    67       * @param stream to wrap
    68       * @param bufferSize minimum chunk size (excluding last chunk)
    69       * @throws IOException
    70       *
    71       * @since 3.0
    72       */
    73      public ChunkedOutputStream(OutputStream stream, int bufferSize) throws IOException {
    74          this.cache = new byte[bufferSize];
    75          this.stream = stream;
    76      }
    77
    78      /**
    79       * Wraps a stream and chunks the output. The default buffer size of 2048 was chosen because
    80       * the chunk overhead is less than 0.5%
    81       * @param stream
    82       * @throws IOException
    83       */
    84      public ChunkedOutputStream(OutputStream stream) throws IOException {
    85          this(stream, 2048);
    86      }
    87
    88      // ----------------------------------------------------------- Internal methods
    89      /**
    90       * Writes the cache out onto the underlying stream
    91       * @throws IOException
    92       *
    93       * @since 3.0
    94       */
    95      protected void flushCache() throws IOException {
    96          if (cachePosition > 0) {
    97              byte chunkHeader[] = EncodingUtil.getAsciiBytes(
    98                      Integer.toHexString(cachePosition) + "\r\n");
    99              stream.write(chunkHeader, 0, chunkHeader.length);
    100             stream.write(cache, 0, cachePosition);
    101             stream.write(ENDCHUNK, 0, ENDCHUNK.length);
    102             cachePosition = 0;
    103         }
    104     }
    105
    106     /**
    107      * Writes the cache and bufferToAppend to the underlying stream
    108      * as one large chunk
    109      * @param bufferToAppend
    110      * @param off
    111      * @param len
    112      * @throws IOException
    113      *
    114      * @since 3.0
    115      */
    116     protected void flushCacheWithAppend(byte bufferToAppend[], int off, int len) throws IOException {
    117         byte chunkHeader[] = EncodingUtil.getAsciiBytes(
    118                 Integer.toHexString(cachePosition + len) + "\r\n");
    119         stream.write(chunkHeader, 0, chunkHeader.length);
    120         stream.write(cache, 0, cachePosition);
    121         stream.write(bufferToAppend, off, len);
    122         stream.write(ENDCHUNK, 0, ENDCHUNK.length);
    123         cachePosition = 0;
    124     }
    125
    126     protected void writeClosingChunk() throws IOException {
    127         // Write the final chunk.
    128
    129         stream.write(ZERO, 0, ZERO.length);
    130         stream.write(CRLF, 0, CRLF.length);
    131         stream.write(ENDCHUNK, 0, ENDCHUNK.length);
    132     }
    133
    134     // ----------------------------------------------------------- Public Methods
    135     /**
    136      * Must be called to ensure the internal cache is flushed and the closing chunk is written.
    137      * @throws IOException
    138      *
    139      * @since 3.0
    140      */
    141     public void finish() throws IOException {
    142         if (!wroteLastChunk) {
    143             flushCache();
    144             writeClosingChunk();
    145             wroteLastChunk = true;
    146         }
    147     }
    148
    149     // -------------------------------------------- OutputStream Methods
    150     /**
    151      * Write the specified byte to our output stream.
    152      *
    153      * Note: Avoid this method as it will cause an inefficient single byte chunk.
    154      * Use write (byte[], int, int) instead.
    155      *
    156      * @param b The byte to be written
    157      * @throws IOException if an input/output error occurs
    158      */
    159     public void write(int b) throws IOException {
    160         cache[cachePosition] = (byte) b;
    161         cachePosition++;
    162         if (cachePosition == cache.length) flushCache();
    163     }
    164
    165     /**
    166      * Writes the array. If the array does not fit within the buffer, it is
    167      * not split, but rather written out as one large chunk.
    168      * @param b
    169      * @throws IOException
    170      *
    171      * @since 3.0
    172      */
    173     public void write(byte b[]) throws IOException {
    174         this.write(b, 0, b.length);
    175     }
    176
    177     public void write(byte src[], int off, int len) throws IOException {
    178         if (len >= cache.length - cachePosition) {
    179             flushCacheWithAppend(src, off, len);
    180         } else {
    181             System.arraycopy(src, off, cache, cachePosition, len);
    182             cachePosition += len;
    183         }
    184     }
    185
    186     /**
    187      * Flushes the underlying stream, but leaves the internal buffer alone.
    188      * @throws IOException
    189      */
    190     public void flush() throws IOException {
    191         stream.flush();
    192     }
    193
    194     /**
    195      * Finishes writing to the underlying stream, but does NOT close the underlying stream.
    196      * @throws IOException
    197      */
    198     public void close() throws IOException {
    199         finish();
    200         super.close();
    201     }
    202 }