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/*
* $Id$
*
* This file is part of the OpenLink Software Virtuoso Open-Source (VOS)
* project.
*
* Copyright (C) 1998-2012 OpenLink Software
*
* This project is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; only version 2 of the License, dated June 1991.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
package virtuoso.jdbc2;
import java.io.*;
/**
* The VirtuosoBlobStream is used to get a blob into an input
* stream.
*
* @version 1.0 (JDBC API 2.0 implementation)
*/
class VirtuosoBlobStream extends InputStream
{
// The blob attached to this stream
private VirtuosoBlob blob;
// The actual position into the blob
protected long pos = 1;
/**
* Constructs a VirtuosoBlobStream using a blob.
*
* @param blob The blob to get.
*/
VirtuosoBlobStream(VirtuosoBlob blob)
{
this.blob = blob;
}
// ------------------------ InputStream -----------------------------
/**
* Reads the next byte of data from this input stream. The value
* byte is returned as an <code>int</code> in the range
* <code>0</code> to <code>255</code>. If no byte is available
* because the end of the stream has been reached, the value
* <code>-1</code> is returned. This method blocks until input data
* is available, the end of the stream is detected, or an exception
* is thrown.
*
* @return the next byte of data, or <code>-1</code> if the end of the
* stream is reached.
* @exception IOException if an I/O error occurs.
*/
public int read() throws IOException
{
try
{
// Check if it's the end of the stream
return (pos > blob.length()) ? -1 : (blob.getBytes(pos++,1))[0];
}
catch(Exception e)
{
throw new IOException(e.getMessage());
}
}
/**
* Reads up to <code>len</code> bytes of data from this input stream
* into an array of bytes. This method blocks until some input is
* available. If the argument <code>b</code> is <code>null</code>, a
* <code>NullPointerException</code> is thrown.
*
* @param b the buffer into which the data is read.
* @param off the start offset of the data.
* @param len the maximum number of bytes read.
* @return the total number of bytes read into the buffer, or
* <code>-1</code> if there is no more data because the end of
* the stream has been reached.
* @exception IOException if an I/O error occurs.
* @see java.io.InputStream#read()
*/
public int read(byte b[], int off, int len) throws IOException
{
//System.err.println ("Stream read: off=" + off + " len=" + len + " pos=" + pos);
try
{
byte[] bytes = null;
// Check parameters
if(len <= 0)
return 0;
// Check if it's the end of the stream
if((pos + len) > blob.length())
{
int to_read = (int)(blob.length() - pos + 1);
//System.out.println ("larger pos=" + pos + " len=" + len + " bloblen=" + blob.length());
if (to_read > 0)
bytes = blob.getBytes(pos,to_read);
if (bytes != null)
{
System.arraycopy(bytes,0,b,off,to_read);
pos = blob.length() + 1;
return bytes.length;
}
else
return -1;
}
// Read the byte
bytes = blob.getBytes(pos,len);
if (bytes != null)
{
System.arraycopy(bytes,0,b,off,len);
pos += bytes.length;
return bytes.length;
}
else return -1;
}
catch(Exception e)
{
throw new IOException(e.getMessage());
}
}
/**
* Skips over and discards <code>n</code> bytes of data from this
* input stream. The <code>skip</code> method may, for a variety of
* reasons, end up skipping over some smaller number of bytes,
* possibly <code>0</code>. The actual number of bytes skipped is
* returned.
*
* @param n the number of bytes to be skipped.
* @return the actual number of bytes skipped.
* @exception IOException if an I/O error occurs.
* @since JDK1.0
*/
public long skip(long n) throws IOException
{
try
{
// Check parameters
if(n <= 0)
return 0;
// Skip n bytes
if((pos + n) > blob.length())
{
long _prov = blob.length() - pos + 1;
pos = blob.length();
return _prov;
}
pos += n;
return n;
}
catch(Exception e)
{
throw new IOException(e.getMessage());
}
}
/**
* Returns the number of bytes that can be read from this input
* stream without blocking. The available method of
*
* @return the number of bytes that can be read from this input stream
* without blocking.
* @exception IOException if an I/O error occurs.
*/
public int available() throws IOException
{
try
{
return (int)(blob.length() - pos + 1);
}
catch(Exception e)
{
throw new IOException(e.getMessage());
}
}
public void reset ()
{
pos = 1;
}
}
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