1 /*

     2 * Copyright (c) 2002 Nokia Corporation and/or its subsidiary(-ies).

     3 * All rights reserved.

     4 * This component and the accompanying materials are made available

     5 * under the terms of "Eclipse Public License v1.0"

     6 * which accompanies this distribution, and is available

     7 * at the URL "http://www.eclipse.org/legal/epl-v10.html".

     8 *

     9 * Initial Contributors:

    10 * Nokia Corporation - initial contribution.

    11 *

    12 * Contributors:

    13 *

    14 * Description:  SourceStream that buffers data from another SourceStream.

    15 *

    16 */

    17 

    18 

    19 package com.nokia.microedition.media;

    20 

    21 import java.io.IOException;

    22 import javax.microedition.media.protocol.SourceStream;

    23 

    24 /**

    25  * SourceStream that buffers data from another SourceStream.

    26  *

    27  */

    28 public class BufferSourceStream extends InputStreamSourceStream

    29 {

    30     // Deferred buffer size

    31     private static final int BUFFER_SIZE = 5120;

    32 

    33     // Stream to buffer

    34     SourceStream iSourceStream;

    35 

    36     byte[] iBuffer;

    37 

    38     // stream read position

    39     int iPos;

    40 

    41     /**

    42      * Constructor.

    43      * @param aInputStream An InputStream

    44      */

    45     public BufferSourceStream(SourceStream aSourceStream)

    46     {

    47         iSourceStream = aSourceStream;

    48     }

    49 

    50     /**

    51      * Return header data.

    52      * @return header data

    53      */

    54     public byte[] getHeader() throws IOException

    55     {

    56         byte[] tmpBuffer = new byte[ BUFFER_SIZE ];

    57         int bytesInBuffer = BUFFER_SIZE;

    58 

    59         // Read into iBuffer first if iBuffer doesn't already contain

    60         // first 256 bytes

    61         if (iBuffer == null)

    62         {

    63             bytesInBuffer = readAndBuffer(tmpBuffer, 0, 256);

    64 

    65             if (bytesInBuffer < 0)

    66             {

    67                 throw new IOException();

    68             }

    69         }

    70         else if (iBuffer.length < 256)

    71         {

    72             bytesInBuffer = readAndBuffer(tmpBuffer, iBuffer.length, (256 - iBuffer.length));

    73 

    74             if (bytesInBuffer == -1)

    75             {

    76                 bytesInBuffer = iBuffer.length;

    77             }

    78         }

    79 

    80         // tmpBuffer will be overwritten here

    81         System.arraycopy(iBuffer, 0,

    82                          tmpBuffer, 0, bytesInBuffer);

    83 

    84         return tmpBuffer;

    85     }

    86 

    87 

    88     public int readAndBuffer(byte[] aBuffer, int aOffset, int aLength) throws IOException

    89     {

    90         int bytesInBuffer = iSourceStream.read(aBuffer, aOffset, aLength);

    91 

    92         if (iBuffer == null)

    93         {

    94             iBuffer = new byte[bytesInBuffer];

    95 

    96             System.arraycopy(aBuffer, aOffset,

    97                              iBuffer, 0, bytesInBuffer);

    98         }

    99         else if (bytesInBuffer >= 0)

   100         {

   101             byte[] tempBuffer = iBuffer;

   102             iBuffer = new byte[iBuffer.length + bytesInBuffer];

   103 

   104             System.arraycopy(tempBuffer, 0,

   105                              iBuffer, 0, tempBuffer.length);

   106             System.arraycopy(aBuffer, aOffset,

   107                              iBuffer, tempBuffer.length, bytesInBuffer);

   108             tempBuffer = null; // relese tempBuffer

   109         }

   110 

   111         return bytesInBuffer;

   112     }

   113 

   114     /**

   115      * Read from Input Stream

   116      * @param buffer Input Stream

   117      * @param offset where reading starts

   118      * @param length length of read data

   119      * @return bytes read

   120      * @throws IOException

   121      */

   122     public int read(byte[] aBuffer, int aOffset, int aLength) throws IOException

   123     {

   124         // bytes read from internal buffer

   125         int bytesFromBuffer = 0;

   126 

   127 

   128         if ((iBuffer != null) &&   // read from iBuffer if getHeader is called

   129                 (iPos < iBuffer.length))

   130         {

   131             // Need to read from buffer

   132             if (aLength < iBuffer.length - iPos)

   133             {

   134                 // aLength bytes can be read from buffer

   135                 bytesFromBuffer = aLength;

   136             }

   137             else

   138             {

   139                 // aLength cannot be read from buffer

   140                 // read all there is available

   141                 bytesFromBuffer = iBuffer.length - iPos;

   142             }

   143 

   144             System.arraycopy(iBuffer, iPos,

   145                              aBuffer, aOffset, bytesFromBuffer);

   146 

   147             // move stream position

   148             iPos += bytesFromBuffer;

   149             return bytesFromBuffer;

   150         }

   151 

   152         // bytes read from iSourceStream

   153         int bytesFromStream = 0;

   154         // Check if bytes are needed from SourceStream

   155         if (bytesFromBuffer < aLength)

   156         {

   157             bytesFromStream = iSourceStream.read(aBuffer,

   158                                                  bytesFromBuffer,

   159                                                  aLength - bytesFromBuffer);

   160             if (bytesFromStream != -1)

   161             {

   162                 // move stream position, if not end of stream

   163                 iPos += bytesFromStream;

   164             }

   165         }

   166 

   167         return bytesFromStream;

   168     }

   169 }

   170 

   171 // End of File