    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.imaging.common.bytesource;
    018
    019import java.io.IOException;
    020import java.io.InputStream;
    021
    022import org.apache.commons.imaging.common.BinaryFunctions;
    023
    024public abstract class ByteSource {
    025    private final String fileName;
    026
    027    public ByteSource(final String fileName) {
    028        this.fileName = fileName;
    029    }
    030
    031    public final InputStream getInputStream(final long start) throws IOException {
    032        InputStream is = null;
    033        boolean succeeded = false;
    034        try {
    035            is = getInputStream();
    036            BinaryFunctions.skipBytes(is, start);
    037            succeeded = true;
    038        } finally {
    039            if (!succeeded && is != null) {
    040                is.close();
    041            }
    042        }
    043        return is;
    044    }
    045
    046    public abstract InputStream getInputStream() throws IOException;
    047
    048    public byte[] getBlock(final int start, final int length) throws IOException {
    049        return getBlock(0xFFFFffffL & start, length);
    050    }
    051
    052    public abstract byte[] getBlock(long start, int length) throws IOException;
    053
    054    public abstract byte[] getAll() throws IOException;
    055
    056    /**
    057     * This operation can be VERY expensive; for inputstream byte sources, the
    058     * entire stream must be drained to determine its length.
    059     *
    060     * @return the byte source length
    061     * @throws IOException if it fails to read the byte source data
    062     */
    063    public abstract long getLength() throws IOException;
    064
    065    public abstract String getDescription();
    066
    067    public final String getFileName() {
    068        return fileName;
    069    }
    070
    071}