org.apache.avro.util.ByteBufferInputStream 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.avro.util;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.util.List;
/** Utility to present {@link ByteBuffer} data as an {@link InputStream}.*/
public class ByteBufferInputStream extends InputStream {
private List buffers;
private int current;
public ByteBufferInputStream(List buffers) {
this.buffers = buffers;
}
/** @see InputStream#read()
* @throws EOFException if EOF is reached. */
@Override
public int read() throws IOException {
return getBuffer().get() & 0xff;
}
/** @see InputStream#read(byte[], int, int)
* @throws EOFException if EOF is reached before reading all the bytes. */
@Override
public int read(byte[] b, int off, int len) throws IOException {
if (len == 0) return 0;
ByteBuffer buffer = getBuffer();
int remaining = buffer.remaining();
if (len > remaining) {
buffer.get(b, off, remaining);
return remaining;
} else {
buffer.get(b, off, len);
return len;
}
}
/** Read a buffer from the input without copying, if possible.
* @throws EOFException if EOF is reached before reading all the bytes. */
public ByteBuffer readBuffer(int length) throws IOException {
if (length == 0) return ByteBuffer.allocate(0);
ByteBuffer buffer = getBuffer();
if (buffer.remaining() == length) { // can return current as-is?
current++;
return buffer; // return w/o copying
}
// punt: allocate a new buffer & copy into it
ByteBuffer result = ByteBuffer.allocate(length);
int start = 0;
while (start < length)
start += read(result.array(), start, length-start);
return result;
}
/** Returns the next non-empty buffer.
* @throws EOFException if EOF is reached before reading all the bytes.
*/
private ByteBuffer getBuffer() throws IOException {
while (current < buffers.size()) {
ByteBuffer buffer = buffers.get(current);
if (buffer.hasRemaining())
return buffer;
current++;
}
throw new EOFException();
}
}