    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 */
    017
    018package org.apache.commons.codec.net;
    019
    020import java.io.UnsupportedEncodingException;
    021import java.nio.charset.Charset;
    022import java.nio.charset.StandardCharsets;
    023
    024import org.apache.commons.codec.DecoderException;
    025import org.apache.commons.codec.EncoderException;
    026import org.apache.commons.codec.StringDecoder;
    027import org.apache.commons.codec.StringEncoder;
    028import org.apache.commons.codec.binary.Base64;
    029
    030/**
    031 * Identical to the Base64 encoding defined by <a href="http://www.ietf.org/rfc/rfc1521.txt">RFC 1521</a>
    032 * and allows a character set to be specified.
    033 * <p>
    034 * <a href="http://www.ietf.org/rfc/rfc1522.txt">RFC 1522</a> describes techniques to allow the encoding of non-ASCII
    035 * text in various portions of a RFC 822 [2] message header, in a manner which is unlikely to confuse existing message
    036 * handling software.
    037 * <p>
    038 * This class is immutable and thread-safe.
    039 *
    040 * @see <a href="http://www.ietf.org/rfc/rfc1522.txt">MIME (Multipurpose Internet Mail Extensions) Part Two: Message
    041 *          Header Extensions for Non-ASCII Text</a>
    042 *
    043 * @since 1.3
    044 */
    045public class BCodec extends RFC1522Codec implements StringEncoder, StringDecoder {
    046    /**
    047     * The default Charset used for string decoding and encoding.
    048     */
    049    private final Charset charset;
    050
    051    /**
    052     * Default constructor.
    053     */
    054    public BCodec() {
    055        this(StandardCharsets.UTF_8);
    056    }
    057
    058    /**
    059     * Constructor which allows for the selection of a default Charset
    060     *
    061     * @param charset
    062     *            the default string Charset to use.
    063     *
    064     * @see <a href="http://download.oracle.com/javase/7/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
    065     * @since 1.7
    066     */
    067    public BCodec(final Charset charset) {
    068        this.charset = charset;
    069    }
    070
    071    /**
    072     * Constructor which allows for the selection of a default Charset
    073     *
    074     * @param charsetName
    075     *            the default Charset to use.
    076     * @throws java.nio.charset.UnsupportedCharsetException
    077     *             If the named Charset is unavailable
    078     * @since 1.7 throws UnsupportedCharsetException if the named Charset is unavailable
    079     * @see <a href="http://download.oracle.com/javase/7/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
    080     */
    081    public BCodec(final String charsetName) {
    082        this(Charset.forName(charsetName));
    083    }
    084
    085    @Override
    086    protected String getEncoding() {
    087        return "B";
    088    }
    089
    090    @Override
    091    protected byte[] doEncoding(final byte[] bytes) {
    092        if (bytes == null) {
    093            return null;
    094        }
    095        return Base64.encodeBase64(bytes);
    096    }
    097
    098    @Override
    099    protected byte[] doDecoding(final byte[] bytes) {
    100        if (bytes == null) {
    101            return null;
    102        }
    103        return Base64.decodeBase64(bytes);
    104    }
    105
    106    /**
    107     * Encodes a string into its Base64 form using the specified Charset. Unsafe characters are escaped.
    108     *
    109     * @param strSource
    110     *            string to convert to Base64 form
    111     * @param sourceCharset
    112     *            the Charset for {@code value}
    113     * @return Base64 string
    114     * @throws EncoderException
    115     *             thrown if a failure condition is encountered during the encoding process.
    116     * @since 1.7
    117     */
    118    public String encode(final String strSource, final Charset sourceCharset) throws EncoderException {
    119        if (strSource == null) {
    120            return null;
    121        }
    122        return encodeText(strSource, sourceCharset);
    123    }
    124
    125    /**
    126     * Encodes a string into its Base64 form using the specified Charset. Unsafe characters are escaped.
    127     *
    128     * @param strSource
    129     *            string to convert to Base64 form
    130     * @param sourceCharset
    131     *            the Charset for {@code value}
    132     * @return Base64 string
    133     * @throws EncoderException
    134     *             thrown if a failure condition is encountered during the encoding process.
    135     */
    136    public String encode(final String strSource, final String sourceCharset) throws EncoderException {
    137        if (strSource == null) {
    138            return null;
    139        }
    140        try {
    141            return this.encodeText(strSource, sourceCharset);
    142        } catch (final UnsupportedEncodingException e) {
    143            throw new EncoderException(e.getMessage(), e);
    144        }
    145    }
    146
    147    /**
    148     * Encodes a string into its Base64 form using the default Charset. Unsafe characters are escaped.
    149     *
    150     * @param strSource
    151     *            string to convert to Base64 form
    152     * @return Base64 string
    153     * @throws EncoderException
    154     *             thrown if a failure condition is encountered during the encoding process.
    155     */
    156    @Override
    157    public String encode(final String strSource) throws EncoderException {
    158        if (strSource == null) {
    159            return null;
    160        }
    161        return encode(strSource, this.getCharset());
    162    }
    163
    164    /**
    165     * Decodes a Base64 string into its original form. Escaped characters are converted back to their original
    166     * representation.
    167     *
    168     * @param value
    169     *            Base64 string to convert into its original form
    170     * @return original string
    171     * @throws DecoderException
    172     *             A decoder exception is thrown if a failure condition is encountered during the decode process.
    173     */
    174    @Override
    175    public String decode(final String value) throws DecoderException {
    176        if (value == null) {
    177            return null;
    178        }
    179        try {
    180            return this.decodeText(value);
    181        } catch (final UnsupportedEncodingException | IllegalArgumentException e) {
    182            throw new DecoderException(e.getMessage(), e);
    183        }
    184    }
    185
    186    /**
    187     * Encodes an object into its Base64 form using the default Charset. Unsafe characters are escaped.
    188     *
    189     * @param value
    190     *            object to convert to Base64 form
    191     * @return Base64 object
    192     * @throws EncoderException
    193     *             thrown if a failure condition is encountered during the encoding process.
    194     */
    195    @Override
    196    public Object encode(final Object value) throws EncoderException {
    197        if (value == null) {
    198            return null;
    199        } else if (value instanceof String) {
    200            return encode((String) value);
    201        } else {
    202            throw new EncoderException("Objects of type " +
    203                  value.getClass().getName() +
    204                  " cannot be encoded using BCodec");
    205        }
    206    }
    207
    208    /**
    209     * Decodes a Base64 object into its original form. Escaped characters are converted back to their original
    210     * representation.
    211     *
    212     * @param value
    213     *            Base64 object to convert into its original form
    214     * @return original object
    215     * @throws DecoderException
    216     *             Thrown if the argument is not a {@code String}. Thrown if a failure condition is encountered
    217     *             during the decode process.
    218     */
    219    @Override
    220    public Object decode(final Object value) throws DecoderException {
    221        if (value == null) {
    222            return null;
    223        } else if (value instanceof String) {
    224            return decode((String) value);
    225        } else {
    226            throw new DecoderException("Objects of type " +
    227                  value.getClass().getName() +
    228                  " cannot be decoded using BCodec");
    229        }
    230    }
    231
    232    /**
    233     * Gets the default Charset name used for string decoding and encoding.
    234     *
    235     * @return the default Charset name
    236     * @since 1.7
    237     */
    238    public Charset getCharset() {
    239        return this.charset;
    240    }
    241
    242    /**
    243     * Gets the default Charset name used for string decoding and encoding.
    244     *
    245     * @return the default Charset name
    246     */
    247    public String getDefaultCharset() {
    248        return this.charset.name();
    249    }
    250}