org.apache.commons.crypto.stream.input.ChannelInput Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.crypto.stream.input;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.ReadableByteChannel;
import org.apache.commons.crypto.stream.CryptoInputStream;
/**
* The ChannelInput class takes a {@link ReadableByteChannel} object and
* wraps it as {@link Input} object acceptable by
* {@link CryptoInputStream}.
*/
public class ChannelInput implements Input {
private static final int SKIP_BUFFER_SIZE = 2048;
private ByteBuffer buf;
private final ReadableByteChannel channel;
/**
* Constructs the
* {@link org.apache.commons.crypto.stream.input.ChannelInput}.
*
* @param channel the ReadableByteChannel object.
*/
public ChannelInput(final ReadableByteChannel channel) {
this.channel = channel;
}
/**
* Overrides the {@link Input#available()}. 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 if an I/O error occurs.
*/
@Override
public int available() throws IOException {
return 0;
}
/**
* Overrides the
* {@link org.apache.commons.crypto.stream.input.Input#seek(long)}. Closes
* this input and releases any system resources associated with the under
* layer input.
*
* @throws IOException if an I/O error occurs.
*/
@Override
public void close() throws IOException {
channel.close();
}
/**
* Gets the skip buffer.
*
* @return the buffer.
*/
private ByteBuffer getSkipBuf() {
if (buf == null) {
buf = ByteBuffer.allocate(SKIP_BUFFER_SIZE);
}
return buf;
}
/**
* Overrides the
* {@link org.apache.commons.crypto.stream.input.Input#read(ByteBuffer)}.
* Reads a sequence of bytes from input into the given buffer.
*
* @param dst The buffer into which bytes are to be transferred.
* @return the total number of bytes read into the buffer, or
* {@code -1} if there is no more data because the end of the
* stream has been reached.
* @throws IOException if an I/O error occurs.
*/
@Override
public int read(final ByteBuffer dst) throws IOException {
return channel.read(dst);
}
/**
* Overrides the
* {@link org.apache.commons.crypto.stream.input.Input#read(long, byte[], int, int)}
* . Reads up to {@code len} bytes of data from the input stream into
* an array of bytes. An attempt is made to read as many as {@code len}
* bytes, but a smaller number may be read. The number of bytes actually
* read is returned as an integer.
*
* @param position the given position within a stream.
* @param buffer the buffer into which the data is read.
* @param offset the start offset in array buffer.
* @param length the maximum number of bytes to read.
* @return the total number of bytes read into the buffer, or
* {@code -1} if there is no more data because the end of the
* stream has been reached.
* @throws IOException if an I/O error occurs.
*/
@Override
public int read(final long position, final byte[] buffer, final int offset, final int length)
throws IOException {
throw new UnsupportedOperationException(
"Positioned read is not supported by this implementation");
}
/**
* Overrides the
* {@link org.apache.commons.crypto.stream.input.Input#seek(long)}. Seeks to
* the given offset from the start of the stream. The next read() will be
* from that location.
*
* @param position the offset from the start of the stream.
* @throws IOException if an I/O error occurs.
*/
@Override
public void seek(final long position) throws IOException {
throw new UnsupportedOperationException(
"Seek is not supported by this implementation");
}
/**
* Overrides the
* {@link org.apache.commons.crypto.stream.input.Input#skip(long)}. Skips
* over and discards {@code n} bytes of data from this input stream.
*
* @param n the number of bytes to be skipped.
* @return the actual number of bytes skipped.
* @throws IOException if an I/O error occurs.
*/
@Override
public long skip(final long n) throws IOException {
long remaining = n;
int nr;
if (n <= 0) {
return 0;
}
final int size = (int) Math.min(SKIP_BUFFER_SIZE, remaining);
final ByteBuffer skipBuffer = getSkipBuf();
while (remaining > 0) {
skipBuffer.clear();
skipBuffer.limit((int) Math.min(size, remaining));
nr = read(skipBuffer);
if (nr < 0) {
break;
}
remaining -= nr;
}
return n - remaining;
}
}