Resettable File InputStream
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import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
/**
* @author Federico Barbieri <fede@apache.org>
*/
public class ResettableFileInputStream
extends InputStream
{
protected static final int DEFAULT_BUFFER_SIZE = 1024;
protected final String m_filename;
protected int m_bufferSize;
protected InputStream m_inputStream;
protected long m_position;
protected long m_mark;
protected boolean m_isMarkSet;
public ResettableFileInputStream( final File file )
throws IOException
{
this( file.getCanonicalPath() );
}
public ResettableFileInputStream( final String filename )
throws IOException
{
this( filename, DEFAULT_BUFFER_SIZE );
}
public ResettableFileInputStream( final String filename, final int bufferSize )
throws IOException
{
m_bufferSize = bufferSize;
m_filename = filename;
m_position = 0;
m_inputStream = newStream();
}
public void mark( final int readLimit )
{
m_isMarkSet = true;
m_mark = m_position;
m_inputStream.mark( readLimit );
}
public boolean markSupported()
{
return true;
}
public void reset()
throws IOException
{
if( !m_isMarkSet )
{
throw new IOException( "Unmarked Stream" );
}
try
{
m_inputStream.reset();
}
catch( final IOException ioe )
{
try
{
m_inputStream.close();
m_inputStream = newStream();
m_inputStream.skip( m_mark );
m_position = m_mark;
}
catch( final Exception e )
{
throw new IOException( "Cannot reset current Stream: " + e.getMessage() );
}
}
}
protected InputStream newStream()
throws IOException
{
return new BufferedInputStream( new FileInputStream( m_filename ), m_bufferSize );
}
public int available()
throws IOException
{
return m_inputStream.available();
}
public void close() throws IOException
{
m_inputStream.close();
}
public int read() throws IOException
{
m_position++;
return m_inputStream.read();
}
public int read( final byte[] bytes, final int offset, final int length )
throws IOException
{
final int count = m_inputStream.read( bytes, offset, length );
m_position += count;
return count;
}
public long skip( final long count )
throws IOException
{
m_position += count;
return m_inputStream.skip( count );
}
}
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