| /** |
| * 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.hama.util; |
| |
| import java.io.ByteArrayInputStream; |
| import java.io.IOException; |
| import java.io.InputStream; |
| |
| |
| /** |
| * This class, much like {@link ByteArrayInputStream} uses a given buffer as a |
| * source of an InputStream. Unlike ByteArrayInputStream, this class does not |
| * "waste" memory by creating a local copy of the given buffer, but rather uses |
| * the given buffer as is. Hence the name Unsafe. While using this class one |
| * should remember that the byte[] buffer memory is shared and might be changed |
| * from outside. |
| * |
| * For reuse-ability, a call for {@link #reInit(byte[])} can be called, and |
| * initialize the stream with a new buffer. |
| * |
| */ |
| public class UnsafeByteArrayInputStream extends InputStream { |
| private byte[] buffer; |
| private int markIndex; |
| private int upperLimit; |
| private int index; |
| |
| /** |
| * Creates a new instance by not using any byte[] up front. If you use this |
| * constructor, you MUST call either of the {@link #reInit(byte[]) reInit} |
| * methods before you consume any byte from this instance.<br> |
| * This constructor is for convenience purposes only, so that if one does not |
| * have the byte[] at the moment of creation, one is not forced to pass a |
| * <code>new byte[0]</code> or something. Obviously in that case, one will |
| * call either {@link #reInit(byte[]) reInit} methods before using the class. |
| */ |
| public UnsafeByteArrayInputStream() { |
| markIndex = upperLimit = index = 0; |
| } |
| |
| /** |
| * Creates an UnsafeByteArrayInputStream which uses a given byte array as the |
| * source of the stream. Default range is [0 , buffer.length) |
| * |
| * @param buffer byte array used as the source of this stream |
| */ |
| public UnsafeByteArrayInputStream(byte[] buffer) { |
| reInit(buffer, 0, buffer.length); |
| } |
| |
| /** |
| * Creates an UnsafeByteArrayInputStream which uses a given byte array as the |
| * source of the stream, at the specific range: [startPos, endPos) |
| * |
| * @param buffer byte array used as the source of this stream |
| * @param startPos first index (inclusive) to the data lying in the given |
| * buffer |
| * @param endPos an index (exclusive) where the data ends. data @ |
| * buffer[endPos] will never be read |
| */ |
| public UnsafeByteArrayInputStream(byte[] buffer, int startPos, int endPos) { |
| reInit(buffer, startPos, endPos); |
| } |
| |
| @Override |
| public void mark(int readlimit) { |
| markIndex = index; |
| } |
| |
| @Override |
| public boolean markSupported() { |
| return true; |
| } |
| |
| /** |
| * Initialize the stream with a given buffer, using the default limits of [0, |
| * buffer.length) |
| * |
| * @param buffer byte array used as the source of this stream |
| */ |
| public void reInit(byte[] buffer) { |
| reInit(buffer, 0, buffer.length); |
| } |
| |
| /** |
| * Initialize the stream with a given byte array as the source of the stream, |
| * at the specific range: [startPos, endPos) |
| * |
| * @param buffer byte array used as the source of this stream |
| * @param startPos first index (inclusive) to the data lying in the given |
| * buffer |
| * @param endPos an index (exclusive) where the data ends. data @ |
| * buffer[endPos] will never be read |
| */ |
| public void reInit(byte[] buffer, int startPos, int endPos) { |
| this.buffer = buffer; |
| markIndex = startPos; |
| upperLimit = endPos; |
| index = markIndex; |
| } |
| |
| @Override |
| public int available() throws IOException { |
| return upperLimit - index; |
| } |
| |
| /** |
| * Read a byte. Data returned as an integer [0,255] If end of stream reached, |
| * returns -1 |
| */ |
| @Override |
| public int read() throws IOException { |
| return index < upperLimit ? buffer[index++] & 0xff : -1; |
| } |
| |
| /** |
| * Resets the stream back to its original state. Basically - moving the index |
| * back to start position. |
| */ |
| @Override |
| public void reset() throws IOException { |
| index = markIndex; |
| } |
| } |