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    1   /***
    2    *
    3    * Copyright 2004 Protique Ltd
    4    *
    5    * Licensed under the Apache License, Version 2.0 (the "License");
    6    * you may not use this file except in compliance with the License.
    7    * You may obtain a copy of the License at
    8    *
    9    * http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   *
    17   **/
    18
    19  package org.codehaus.activemq.transport.tcp;
    20
    21  import java.io.EOFException;
    22  import java.io.FilterOutputStream;
    23  import java.io.IOException;
    24  import java.io.OutputStream;
    25
    26  /***
    27   * An optimized buffered outputstream for Tcp
    28   *
    29   * @version $Revision: 1.4 $
    30   */
    31
    32  public class TcpBufferedOutputStream extends FilterOutputStream {
    33      private final static int BUFFER_SIZE = 4096;
    34      private byte[] buf;
    35      private int count;
    36
    37      /***
    38       * Constructor
    39       *
    40       * @param out
    41       */
    42      public TcpBufferedOutputStream(OutputStream out) {
    43          this(out, BUFFER_SIZE);
    44      }
    45
    46      /***
    47       * Creates a new buffered output stream to write data to the specified underlying output stream with the specified
    48       * buffer size.
    49       *
    50       * @param out  the underlying output stream.
    51       * @param size the buffer size.
    52       * @throws IllegalArgumentException if size <= 0.
    53       */
    54      public TcpBufferedOutputStream(OutputStream out, int size) {
    55          super(out);
    56          if (size <= 0) {
    57              throw new IllegalArgumentException("Buffer size <= 0");
    58          }
    59          buf = new byte[size];
    60      }
    61
    62      /***
    63       * write a byte on to the stream
    64       *
    65       * @param b - byte to write
    66       * @throws IOException
    67       */
    68      public void write(int b) throws IOException {
    69          checkClosed();
    70          if (availableBufferToWrite() < 1) {
    71              flush();
    72          }
    73          buf[count++] = (byte) b;
    74      }
    75
    76
    77      /***
    78       * write a byte array to the stream
    79       *
    80       * @param b   the byte buffer
    81       * @param off the offset into the buffer
    82       * @param len the length of data to write
    83       * @throws IOException
    84       */
    85      public void write(byte b[], int off, int len) throws IOException {
    86          checkClosed();
    87          if (availableBufferToWrite() < len) {
    88              flush();
    89          }
    90          if (buf.length >= len) {
    91              System.arraycopy(b, off, buf, count, len);
    92              count += len;
    93          }
    94          else {
    95              out.write(b, off, len);
    96          }
    97      }
    98
    99      /***
    100      * flush the data to the output stream
    101      * This doesn't call flush on the underlying outputstream, because
    102      * Tcp is particularly efficent at doing this itself ....
    103      *
    104      * @throws IOException
    105      */
    106     public void flush() throws IOException {
    107         if (count > 0 && out != null) {
    108             out.write(buf, 0, count);
    109             count = 0;
    110         }
    111     }
    112
    113     /***
    114      * close this stream
    115      *
    116      * @throws IOException
    117      */
    118     public void close() throws IOException {
    119         super.close();
    120         out = null;
    121         buf = null;
    122     }
    123
    124
    125     /***
    126      * Checks that the stream has not been closed
    127      *
    128      * @throws IOException
    129      */
    130     protected void checkClosed() throws IOException {
    131         if (buf == null || out == null) {
    132             throw new EOFException("Cannot write to the stream any more it has already been closed");
    133         }
    134     }
    135
    136     /***
    137      * @return the amount free space in the buffer
    138      */
    139     private int availableBufferToWrite() {
    140         return buf.length - count;
    141     }
    142 }