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Apache XML Graphics Commons is a library that consists of several reusable components used by Apache Batik and Apache FOP. Many of these components can easily be used separately outside the domains of SVG and XSL-FO.

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/*
 * 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: SubInputStream.java 1610846 2014-07-15 20:44:18Z vhennebert $ */

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.
 * 

* 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; /** * 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(); } } }





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