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The Apache Commons Codec package contains simple encoder and decoders for various formats such as Base64 and Hexadecimal. In addition to these widely used encoders and decoders, the codec package also maintains a collection of phonetic encoding utilities.

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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.
 */

package org.apache.commons.codec.binary;

import java.io.InputStream;

/**
 * Provides Base64 encoding and decoding in a streaming fashion (unlimited size). When encoding the default lineLength
 * is 76 characters and the default lineEnding is CRLF, but these can be overridden by using the appropriate
 * constructor.
 * 
 * The default behaviour of the Base64InputStream is to DECODE, whereas the default behaviour of the Base64OutputStream
 * is to ENCODE, but this behaviour can be overridden by using a different constructor.
 * 
 * 
 * This class implements section 6.8. Base64 Content-Transfer-Encoding from RFC 2045 Multipurpose
 * Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies by Freed and Borenstein.
 * 
 * 
 * Since this class operates directly on byte streams, and not character streams, it is hard-coded to only encode/decode
 * character encodings which are compatible with the lower 127 ASCII chart (ISO-8859-1, Windows-1252, UTF-8, etc).
 * 
 *
 * @see RFC 2045
 * @since 1.4
 */
public class Base64InputStream extends BaseNCodecInputStream {

    /**
     * Creates a Base64InputStream such that all data read is Base64-decoded from the original provided InputStream.
     *
     * @param in
     *            InputStream to wrap.
     */
    public Base64InputStream(final InputStream in) {
        this(in, false);
    }

    /**
     * Creates a Base64InputStream such that all data read is either Base64-encoded or Base64-decoded from the original
     * provided InputStream.
     *
     * @param in
     *            InputStream to wrap.
     * @param doEncode
     *            true if we should encode all data read from us, false if we should decode.
     */
    public Base64InputStream(final InputStream in, final boolean doEncode) {
        super(in, new Base64(false), doEncode);
    }

    /**
     * Creates a Base64InputStream such that all data read is either Base64-encoded or Base64-decoded from the original
     * provided InputStream.
     *
     * @param in
     *            InputStream to wrap.
     * @param doEncode
     *            true if we should encode all data read from us, false if we should decode.
     * @param lineLength
     *            If doEncode is true, each line of encoded data will contain lineLength characters (rounded down to
     *            nearest multiple of 4). If lineLength <= 0, the encoded data is not divided into lines. If doEncode
     *            is false, lineLength is ignored.
     * @param lineSeparator
     *            If doEncode is true, each line of encoded data will be terminated with this byte sequence (e.g. \r\n).
     *            If lineLength <= 0, the lineSeparator is not used. If doEncode is false lineSeparator is ignored.
     */
    public Base64InputStream(final InputStream in, final boolean doEncode,
                             final int lineLength, final byte[] lineSeparator) {
        super(in, new Base64(lineLength, lineSeparator), doEncode);
    }
}