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Java Machine Readable Travel Documents API.
/*
* JMRTD - A Java API for accessing machine readable travel documents.
*
* Copyright (C) 2006 - 2014 The JMRTD team
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* $Id: SplittableInputStream.java 1573 2015-03-04 16:00:18Z martijno $
*/
package org.jmrtd.io;
import java.io.IOException;
import java.io.InputStream;
import java.util.logging.Logger;
/**
* An input stream which will wrap another input stream (and yield the same bytes) and which can
* spawn new fresh input stream copies (using {@link #getInputStream(int)})
* (that also yield the same bytes).
*
* @author Martijn Oostdijk ([email protected])
*
* @version $Revision: 1573 $
*/
public class SplittableInputStream extends InputStream {
private static final Logger LOGGER = Logger.getLogger("org.jmrtd");
public InputStreamBuffer inputStreamBuffer; // FIXME should be private
private InputStreamBuffer.SubInputStream carrier;
/**
* Wraps an input stream so that copy streams can be split off.
*
* @param inputStream the original input stream
* @param length the precise length of bytes that the original input stream provides
*/
public SplittableInputStream(InputStream inputStream, int length) {
this.inputStreamBuffer = new InputStreamBuffer(inputStream, length);
this.carrier = inputStreamBuffer.getInputStream();
}
public void updateFrom(SplittableInputStream other) {
inputStreamBuffer.updateFrom(other.inputStreamBuffer);
}
/**
* Gets a copy of the inputstream positioned at position.
*
* @param position a position between 0 and {@link #getPosition()}
* @return a fresh input stream
*/
public InputStream getInputStream(int position) {
try {
InputStream inputStream = inputStreamBuffer.getInputStream();
long skippedBytes = 0L;
while (skippedBytes < position) {
skippedBytes += inputStream.skip(position - skippedBytes);
}
return inputStream;
} catch (IOException ioe) {
LOGGER.severe("Exception: " + ioe.getMessage());
throw new IllegalStateException(ioe.getMessage());
}
}
/**
* The position of the input stream (the number of bytes read since this input stream was constructed)
*
* @return the position of this input stream
*/
public int getPosition() {
return carrier.getPosition();
}
/**
* Reads the next byte of data from the input stream. The value byte is
* returned as an int in the range 0 to
* 255. If no byte is available because the end of the stream
* has been reached, the value -1 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 -1 if the end of the
* stream is reached.
* @exception IOException if an I/O error occurs.
*/
public int read() throws IOException {
return carrier.read();
}
/**
* Skips over and discards n bytes of data from this input
* stream. The skip method may, for a variety of reasons, end
* up skipping over some smaller number of bytes, possibly 0.
* This may result from any of a number of conditions; reaching end of file
* before n bytes have been skipped is only one possibility.
* The actual number of bytes skipped is returned. If n is
* negative, no bytes are skipped.
*
* @param n the number of bytes to be skipped.
* @return the actual number of bytes skipped.
* @throws IOException if the stream does not support seek, or if some other I/O error occurs.
*/
public long skip(long n) throws IOException {
return carrier.skip(n);
}
/**
* Returns an estimate of the number of bytes that can be read (or
* skipped over) from this input stream without blocking by the next
* invocation of a method for this input stream. The next invocation
* might be the same thread or another thread. A single read or skip of this
* many bytes will not block, but may read or skip fewer bytes.
*
* @return an estimate of the number of bytes that can be read (or skipped
* over) from this input stream without blocking or {@code 0} when
* it reaches the end of the input stream.
* @throws IOException on error
*/
public int available() throws IOException {
return carrier.available();
}
/**
* Closes this input stream and releases any system resources associated
* with the stream.
*
* @throws IOException on error
*/
public void close() throws IOException {
carrier.close();
}
/**
* Marks the current position in this input stream. A subsequent call to
* the reset method repositions this stream at the last marked
* position so that subsequent reads re-read the same bytes.
*
* The readlimit arguments tells this input stream to
* allow that many bytes to be read before the mark position gets
* invalidated.
*
* The general contract of mark is that, if the method
* markSupported returns true, the stream somehow
* remembers all the bytes read after the call to mark and
* stands ready to supply those same bytes again if and whenever the method
* reset is called. However, the stream is not required to
* remember any data at all if more than readlimit bytes are
* read from the stream before reset is called.
*
* @param readlimit the maximum limit of bytes that can be read before the mark position becomes invalid.
*
* @see java.io.InputStream#reset()
*/
public synchronized void mark(int readlimit) {
carrier.mark(readlimit);
}
/**
* Repositions this stream to the position at the time the
* mark method was last called on this input stream.
*
* The general contract of reset is:
*
*
*
* - If the method
markSupported returns
* true, then:
*
* - If the method
mark has not been called since
* the stream was created, or the number of bytes read from the stream
* since mark was last called is larger than the argument
* to mark at that last call, then an
* IOException might be thrown.
*
* - If such an
IOException is not thrown, then the
* stream is reset to a state such that all the bytes read since the
* most recent call to mark (or since the start of the
* file, if mark has not been called) will be resupplied
* to subsequent callers of the read method, followed by
* any bytes that otherwise would have been the next input data as of
* the time of the call to reset.
*
* - If the method
markSupported returns
* false, then:
*
* - The call to
reset may throw an
* IOException.
*
* - If an
IOException is not thrown, then the stream
* is reset to a fixed state that depends on the particular type of the
* input stream and how it was created. The bytes that will be supplied
* to subsequent callers of the read method depend on the
* particular type of the input stream.
*
* @exception IOException if this stream has not been marked or if the mark has been invalidated.
*
* @see java.io.InputStream#mark(int)
* @see java.io.IOException
*
* @throws IOException on error
*/
public synchronized void reset() throws IOException {
carrier.reset();
}
/**
* Tests if this input stream supports the mark and
* reset methods. Whether or not mark and
* reset are supported is an invariant property of a
* particular input stream instance. The markSupported method
* of InputStream returns false.
*
* @return true if this stream instance supports the mark
* and reset methods; false otherwise.
* @see java.io.InputStream#mark(int)
* @see java.io.InputStream#reset()
*/
public boolean markSupported() {
return carrier.markSupported();
}
public int getLength() {
return inputStreamBuffer.getLength();
}
public int getBytesBuffered() {
return inputStreamBuffer.getBytesBuffered();
}
}
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