| /* |
| * 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.io.input.buffer; |
| |
| import static org.apache.commons.io.IOUtils.EOF; |
| |
| import java.io.FilterInputStream; |
| import java.io.IOException; |
| import java.io.InputStream; |
| import java.util.Objects; |
| |
| import org.apache.commons.io.IOUtils; |
| |
| /** |
| * Implements a buffered input stream, which is internally based on a {@link CircularByteBuffer}. Unlike the |
| * {@link java.io.BufferedInputStream}, this one doesn't need to reallocate byte arrays internally. |
| * |
| * @since 2.7 |
| */ |
| public class CircularBufferInputStream extends FilterInputStream { |
| |
| /** Internal buffer. */ |
| protected final CircularByteBuffer buffer; |
| |
| /** Internal buffer size. */ |
| protected final int bufferSize; |
| |
| /** Whether we've seen the input stream EOF. */ |
| private boolean eof; |
| |
| /** |
| * Constructs a new instance, which filters the given input stream, and uses a reasonable default buffer size |
| * ({@link IOUtils#DEFAULT_BUFFER_SIZE}). |
| * |
| * @param inputStream The input stream, which is being buffered. |
| */ |
| public CircularBufferInputStream(final InputStream inputStream) { |
| this(inputStream, IOUtils.DEFAULT_BUFFER_SIZE); |
| } |
| |
| /** |
| * Constructs a new instance, which filters the given input stream, and uses the given buffer size. |
| * |
| * @param inputStream The input stream, which is being buffered. |
| * @param bufferSize The size of the {@link CircularByteBuffer}, which is used internally. |
| */ |
| @SuppressWarnings("resource") // Caller closes InputStream |
| public CircularBufferInputStream(final InputStream inputStream, final int bufferSize) { |
| super(Objects.requireNonNull(inputStream, "inputStream")); |
| if (bufferSize <= 0) { |
| throw new IllegalArgumentException("Illegal bufferSize: " + bufferSize); |
| } |
| this.buffer = new CircularByteBuffer(bufferSize); |
| this.bufferSize = bufferSize; |
| this.eof = false; |
| } |
| |
| @Override |
| public void close() throws IOException { |
| super.close(); |
| eof = true; |
| buffer.clear(); |
| } |
| |
| /** |
| * Fills the buffer with the contents of the input stream. |
| * |
| * @throws IOException in case of an error while reading from the input stream. |
| */ |
| protected void fillBuffer() throws IOException { |
| if (eof) { |
| return; |
| } |
| int space = buffer.getSpace(); |
| final byte[] buf = IOUtils.byteArray(space); |
| while (space > 0) { |
| final int res = in.read(buf, 0, space); |
| if (res == EOF) { |
| eof = true; |
| return; |
| } |
| if (res > 0) { |
| buffer.add(buf, 0, res); |
| space -= res; |
| } |
| } |
| } |
| |
| /** |
| * Fills the buffer from the input stream until the given number of bytes have been added to the buffer. |
| * |
| * @param count number of byte to fill into the buffer |
| * @return true if the buffer has bytes |
| * @throws IOException in case of an error while reading from the input stream. |
| */ |
| protected boolean haveBytes(final int count) throws IOException { |
| if (buffer.getCurrentNumberOfBytes() < count) { |
| fillBuffer(); |
| } |
| return buffer.hasBytes(); |
| } |
| |
| @Override |
| public int read() throws IOException { |
| if (!haveBytes(1)) { |
| return EOF; |
| } |
| return buffer.read() & 0xFF; // return unsigned byte |
| } |
| |
| @Override |
| public int read(final byte[] targetBuffer, final int offset, final int length) throws IOException { |
| Objects.requireNonNull(targetBuffer, "targetBuffer"); |
| if (offset < 0) { |
| throw new IllegalArgumentException("Offset must not be negative"); |
| } |
| if (length < 0) { |
| throw new IllegalArgumentException("Length must not be negative"); |
| } |
| if (!haveBytes(length)) { |
| return EOF; |
| } |
| final int result = Math.min(length, buffer.getCurrentNumberOfBytes()); |
| for (int i = 0; i < result; i++) { |
| targetBuffer[offset + i] = buffer.read(); |
| } |
| return result; |
| } |
| } |