| /* |
| * 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. |
| */ |
| |
| /* $Id$ */ |
| |
| package org.apache.xmlgraphics.util.io; |
| |
| import java.io.FilterInputStream; |
| import java.io.IOException; |
| import java.io.InputStream; |
| |
| /** |
| * This class is a FilterInputStream descendant that reads from an underlying InputStream |
| * up to a defined number of bytes or the end of the underlying stream. Closing this InputStream |
| * will not result in the underlying InputStream to be closed, too. |
| * <p> |
| * This InputStream can be used to read chunks from a larger file of which the length is |
| * known in advance. |
| */ |
| public class SubInputStream extends FilterInputStream { |
| |
| /** Indicates the number of bytes remaining to be read from the underlying InputStream. */ |
| private long bytesToRead; |
| |
| /** |
| * Indicates whether the underlying stream should be closed when the {@link #close()} method |
| * is called. |
| */ |
| private boolean closeUnderlying = false; |
| |
| /** |
| * Creates a new SubInputStream. |
| * @param in the InputStream to read from |
| * @param maxLen the maximum number of bytes to read from the underlying InputStream until |
| * the end-of-file is signalled. |
| * @param closeUnderlying true if the underlying stream should be closed when the |
| * {@link #close()} method is called. |
| */ |
| public SubInputStream(InputStream in, long maxLen, boolean closeUnderlying) { |
| super(in); |
| this.bytesToRead = maxLen; |
| this.closeUnderlying = closeUnderlying; |
| } |
| |
| /** |
| * Creates a new SubInputStream. The underlying stream is not closed, when close() is called. |
| * @param in the InputStream to read from |
| * @param maxLen the maximum number of bytes to read from the underlying InputStream until |
| * the end-of-file is signalled. |
| */ |
| public SubInputStream(InputStream in, long maxLen) { |
| this(in, maxLen, false); |
| } |
| |
| /** {@inheritDoc} */ |
| public int read() throws IOException { |
| if (bytesToRead > 0) { |
| int result = super.read(); |
| if (result >= 0) { |
| bytesToRead--; |
| return result; |
| } else { |
| return -1; |
| } |
| } else { |
| return -1; |
| } |
| } |
| |
| /** {@inheritDoc} */ |
| public int read(byte[] b, int off, int len) throws IOException { |
| if (bytesToRead == 0) { |
| return -1; |
| } |
| int effRead = (int)Math.min(bytesToRead, len); |
| //cast to int is safe because len can never be bigger than Integer.MAX_VALUE |
| |
| int result = super.read(b, off, effRead); |
| if (result >= 0) { |
| bytesToRead -= result; |
| } |
| return result; |
| } |
| |
| /** {@inheritDoc} */ |
| public long skip(long n) throws IOException { |
| long effRead = Math.min(bytesToRead, n); |
| long result = super.skip(effRead); |
| bytesToRead -= result; |
| return result; |
| } |
| |
| /** {@inheritDoc} */ |
| public void close() throws IOException { |
| this.bytesToRead = 0; |
| if (this.closeUnderlying) { |
| super.close(); |
| } |
| } |
| } |