BCodec.java

  1. /*
  2.  * Licensed to the Apache Software Foundation (ASF) under one or more
  3.  * contributor license agreements.  See the NOTICE file distributed with
  4.  * this work for additional information regarding copyright ownership.
  5.  * The ASF licenses this file to You under the Apache License, Version 2.0
  6.  * (the "License"); you may not use this file except in compliance with
  7.  * the License.  You may obtain a copy of the License at
  8.  *
  9.  *      http://www.apache.org/licenses/LICENSE-2.0
  10.  *
  11.  * Unless required by applicable law or agreed to in writing, software
  12.  * distributed under the License is distributed on an "AS IS" BASIS,
  13.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14.  * See the License for the specific language governing permissions and
  15.  * limitations under the License.
  16.  */

  18. package org.apache.commons.codec.net;

  20. import java.io.UnsupportedEncodingException;
  21. import java.nio.charset.Charset;

  23. import org.apache.commons.codec.Charsets;
  24. import org.apache.commons.codec.DecoderException;
  25. import org.apache.commons.codec.EncoderException;
  26. import org.apache.commons.codec.StringDecoder;
  27. import org.apache.commons.codec.StringEncoder;
  28. import org.apache.commons.codec.binary.Base64;

  30. /**
  31.  * Identical to the Base64 encoding defined by <a href="http://www.ietf.org/rfc/rfc1521.txt">RFC 1521</a>
  32.  * and allows a character set to be specified.
  33.  * <p>
  34.  * <a href="http://www.ietf.org/rfc/rfc1522.txt">RFC 1522</a> describes techniques to allow the encoding of non-ASCII
  35.  * text in various portions of a RFC 822 [2] message header, in a manner which is unlikely to confuse existing message
  36.  * handling software.
  37.  * <p>
  38.  * This class is immutable and thread-safe.
  39.  *
  40.  * @see <a href="http://www.ietf.org/rfc/rfc1522.txt">MIME (Multipurpose Internet Mail Extensions) Part Two: Message
  41.  *          Header Extensions for Non-ASCII Text</a>
  42.  *
  43.  * @since 1.3
  44.  * @version $Id: BCodec.java 1429868 2013-01-07 16:08:05Z ggregory $
  45.  */
  46. public class BCodec extends RFC1522Codec implements StringEncoder, StringDecoder {
  47.     /**
  48.      * The default charset used for string decoding and encoding.
  49.      */
  50.     private final Charset charset;

  52.     /**
  53.      * Default constructor.
  54.      */
  55.     public BCodec() {
  56.         this(Charsets.UTF_8);
  57.     }

  59.     /**
  60.      * Constructor which allows for the selection of a default charset
  61.      *
  62.      * @param charset
  63.      *            the default string charset to use.
  64.      *
  65.      * @see <a href="http://download.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
  66.      * @since 1.7
  67.      */
  68.     public BCodec(final Charset charset) {
  69.         this.charset = charset;
  70.     }

  72.     /**
  73.      * Constructor which allows for the selection of a default charset
  74.      *
  75.      * @param charsetName
  76.      *            the default charset to use.
  77.      * @throws java.nio.charset.UnsupportedCharsetException
  78.      *             If the named charset is unavailable
  79.      * @since 1.7 throws UnsupportedCharsetException if the named charset is unavailable
  80.      * @see <a href="http://download.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
  81.      */
  82.     public BCodec(final String charsetName) {
  83.         this(Charset.forName(charsetName));
  84.     }

  86.     @Override
  87.     protected String getEncoding() {
  88.         return "B";
  89.     }

  91.     @Override
  92.     protected byte[] doEncoding(final byte[] bytes) {
  93.         if (bytes == null) {
  94.             return null;
  95.         }
  96.         return Base64.encodeBase64(bytes);
  97.     }

  99.     @Override
  100.     protected byte[] doDecoding(final byte[] bytes) {
  101.         if (bytes == null) {
  102.             return null;
  103.         }
  104.         return Base64.decodeBase64(bytes);
  105.     }

  107.     /**
  108.      * Encodes a string into its Base64 form using the specified charset. Unsafe characters are escaped.
  109.      *
  110.      * @param value
  111.      *            string to convert to Base64 form
  112.      * @param charset
  113.      *            the charset for <code>value</code>
  114.      * @return Base64 string
  115.      * @throws EncoderException
  116.      *             thrown if a failure condition is encountered during the encoding process.
  117.      * @since 1.7
  118.      */
  119.     public String encode(final String value, final Charset charset) throws EncoderException {
  120.         if (value == null) {
  121.             return null;
  122.         }
  123.         return encodeText(value, charset);
  124.     }

  126.     /**
  127.      * Encodes a string into its Base64 form using the specified charset. Unsafe characters are escaped.
  128.      *
  129.      * @param value
  130.      *            string to convert to Base64 form
  131.      * @param charset
  132.      *            the charset for <code>value</code>
  133.      * @return Base64 string
  134.      * @throws EncoderException
  135.      *             thrown if a failure condition is encountered during the encoding process.
  136.      */
  137.     public String encode(final String value, final String charset) throws EncoderException {
  138.         if (value == null) {
  139.             return null;
  140.         }
  141.         try {
  142.             return this.encodeText(value, charset);
  143.         } catch (final UnsupportedEncodingException e) {
  144.             throw new EncoderException(e.getMessage(), e);
  145.         }
  146.     }

  148.     /**
  149.      * Encodes a string into its Base64 form using the default charset. Unsafe characters are escaped.
  150.      *
  151.      * @param value
  152.      *            string to convert to Base64 form
  153.      * @return Base64 string
  154.      * @throws EncoderException
  155.      *             thrown if a failure condition is encountered during the encoding process.
  156.      */
  157.     @Override
  158.     public String encode(final String value) throws EncoderException {
  159.         if (value == null) {
  160.             return null;
  161.         }
  162.         return encode(value, this.getCharset());
  163.     }

  165.     /**
  166.      * Decodes a Base64 string into its original form. Escaped characters are converted back to their original
  167.      * representation.
  168.      *
  169.      * @param value
  170.      *            Base64 string to convert into its original form
  171.      * @return original string
  172.      * @throws DecoderException
  173.      *             A decoder exception is thrown if a failure condition is encountered during the decode process.
  174.      */
  175.     @Override
  176.     public String decode(final String value) throws DecoderException {
  177.         if (value == null) {
  178.             return null;
  179.         }
  180.         try {
  181.             return this.decodeText(value);
  182.         } catch (final UnsupportedEncodingException e) {
  183.             throw new DecoderException(e.getMessage(), e);
  184.         }
  185.     }

  187.     /**
  188.      * Encodes an object into its Base64 form using the default charset. Unsafe characters are escaped.
  189.      *
  190.      * @param value
  191.      *            object to convert to Base64 form
  192.      * @return Base64 object
  193.      * @throws EncoderException
  194.      *             thrown if a failure condition is encountered during the encoding process.
  195.      */
  196.     @Override
  197.     public Object encode(final Object value) throws EncoderException {
  198.         if (value == null) {
  199.             return null;
  200.         } else if (value instanceof String) {
  201.             return encode((String) value);
  202.         } else {
  203.             throw new EncoderException("Objects of type " +
  204.                   value.getClass().getName() +
  205.                   " cannot be encoded using BCodec");
  206.         }
  207.     }

  209.     /**
  210.      * Decodes a Base64 object into its original form. Escaped characters are converted back to their original
  211.      * representation.
  212.      *
  213.      * @param value
  214.      *            Base64 object to convert into its original form
  215.      * @return original object
  216.      * @throws DecoderException
  217.      *             Thrown if the argument is not a <code>String</code>. Thrown if a failure condition is encountered
  218.      *             during the decode process.
  219.      */
  220.     @Override
  221.     public Object decode(final Object value) throws DecoderException {
  222.         if (value == null) {
  223.             return null;
  224.         } else if (value instanceof String) {
  225.             return decode((String) value);
  226.         } else {
  227.             throw new DecoderException("Objects of type " +
  228.                   value.getClass().getName() +
  229.                   " cannot be decoded using BCodec");
  230.         }
  231.     }

  233.     /**
  234.      * Gets the default charset name used for string decoding and encoding.
  235.      *
  236.      * @return the default charset name
  237.      * @since 1.7
  238.      */
  239.     public Charset getCharset() {
  240.         return this.charset;
  241.     }

  243.     /**
  244.      * Gets the default charset name used for string decoding and encoding.
  245.      *
  246.      * @return the default charset name
  247.      */
  248.     public String getDefaultCharset() {
  249.         return this.charset.name();
  250.     }
  251. }
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