| /* |
| * 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.pdfbox.io; |
| |
| import java.io.InputStream; |
| import java.io.IOException; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| |
| /** |
| * An InputStream which reads from a RandomAccessRead. |
| * |
| * @author Ben Litchfield |
| * @author John Hewson |
| */ |
| public class RandomAccessInputStream extends InputStream |
| { |
| private static final Log LOG = LogFactory.getLog(RandomAccessInputStream.class); |
| |
| private final RandomAccessRead input; |
| private long position; |
| |
| /** |
| * Creates a new RandomAccessInputStream, with a position of zero. The InputStream will maintain |
| * its own position independent of the RandomAccessRead. |
| * |
| * @param randomAccessRead The RandomAccessRead to read from. |
| */ |
| public RandomAccessInputStream(RandomAccessRead randomAccessRead) |
| { |
| input = randomAccessRead; |
| position = 0; |
| } |
| |
| void restorePosition() throws IOException |
| { |
| input.seek(position); |
| } |
| |
| @Override |
| public int available() throws IOException |
| { |
| return (int) Math.max(0, Math.min(input.length() - position, Integer.MAX_VALUE)); |
| } |
| |
| @Override |
| public int read() throws IOException |
| { |
| restorePosition(); |
| if (input.isEOF()) |
| { |
| return -1; |
| } |
| int b = input.read(); |
| if (b != -1) |
| { |
| position += 1; |
| } |
| else |
| { |
| // should never happen due to prior isEOF() check |
| // unless there is an unsynchronized concurrent access |
| LOG.error("read() returns -1, assumed position: " + |
| position + ", actual position: " + input.getPosition()); |
| } |
| return b; |
| } |
| |
| @Override |
| public int read(byte[] b, int off, int len) throws IOException |
| { |
| restorePosition(); |
| if (input.isEOF()) |
| { |
| return -1; |
| } |
| int n = input.read(b, off, len); |
| if (n != -1) |
| { |
| position += n; |
| } |
| else |
| { |
| // should never happen due to prior isEOF() check |
| // unless there is an unsynchronized concurrent access |
| LOG.error("read() returns -1, assumed position: " + |
| position + ", actual position: " + input.getPosition()); |
| } |
| return n; |
| } |
| |
| @Override |
| public long skip(long n) throws IOException |
| { |
| if (n <= 0) |
| { |
| return 0; |
| } |
| restorePosition(); |
| input.seek(position + n); |
| position += n; |
| return n; |
| } |
| } |