content: /*
   * 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.net;
  
  import java.io.UnsupportedEncodingException;
  
  import org.apache.commons.codec.DecoderException;
  import org.apache.commons.codec.EncoderException;
  import org.apache.commons.codec.CharEncoding;
  import org.apache.commons.codec.StringDecoder;
  import org.apache.commons.codec.StringEncoder;
  import org.apache.commons.codec.binary.Base64;
  
  /**
   * <p>
   * Identical to the Base64 encoding defined by <a href="http://www.ietf.org/rfc/rfc1521.txt">RFC
   * 1521</a> and allows a character set to be specified.
   * </p>
   * 
   * <p>
   * <a href="http://www.ietf.org/rfc/rfc1522.txt">RFC 1522</a> describes techniques to allow the encoding of non-ASCII
   * text in various portions of a RFC 822 [2] message header, in a manner which is unlikely to confuse existing message
   * handling software.
   * </p>
   * 
   * @see <a href="http://www.ietf.org/rfc/rfc1522.txt">MIME (Multipurpose Internet Mail Extensions) Part Two: Message
   *          Header Extensions for Non-ASCII Text</a>
   * 
   * @author Apache Software Foundation
   * @since 1.3
   * @version $Id: BCodec.java 797857 2009-07-25 23:43:33Z ggregory $
   */
  public class BCodec extends RFC1522Codec implements StringEncoder, StringDecoder {
      /**
       * The default charset used for string decoding and encoding.
       */
      private final String charset;
  
      /**
       * Default constructor.
       */
      public BCodec() {
          this(CharEncoding.UTF_8);
      }
  
      /**
       * Constructor which allows for the selection of a default charset
       * 
       * @param charset
       *                  the default string charset to use.
       * 
       * @see <a href="http://java.sun.com/j2se/1.4.2/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
       */
      public BCodec(final String charset) {
          super();
          this.charset = charset;
      }
  
      protected String getEncoding() {
          return "B";
      }
  
      protected byte[] doEncoding(byte[] bytes) {
          if (bytes == null) {
              return null;
          }
          return Base64.encodeBase64(bytes);
      }
  
      protected byte[] doDecoding(byte[] bytes) {
          if (bytes == null) {
              return null;
          }
          return Base64.decodeBase64(bytes);
      }
  
      /**
       * Encodes a string into its Base64 form using the specified charset. Unsafe characters are escaped.
       * 
       * @param value
       *                  string to convert to Base64 form
       * @param charset
       *                  the charset for <code>value</code>
       * @return Base64 string
       * 
       * @throws EncoderException
       *                  thrown if a failure condition is encountered during the encoding process.
       */
      public String encode(final String value, final String charset) throws EncoderException {
          if (value == null) {
              return null;
          }
          try {
              return encodeText(value, charset);
          } catch (UnsupportedEncodingException e) {
              throw new EncoderException(e.getMessage(), e);
          }
      }
  
      /**
       * Encodes a string into its Base64 form using the default charset. Unsafe characters are escaped.
       * 
       * @param value
       *                  string to convert to Base64 form
       * @return Base64 string
       * 
       * @throws EncoderException
       *                  thrown if a failure condition is encountered during the encoding process.
       */
      public String encode(String value) throws EncoderException {
          if (value == null) {
              return null;
          }
          return encode(value, getDefaultCharset());
      }
  
      /**
       * Decodes a Base64 string into its original form. Escaped characters are converted back to their original
       * representation.
       * 
       * @param value
       *            Base64 string to convert into its original form
       * @return original string
       * @throws DecoderException
       *             A decoder exception is thrown if a failure condition is encountered during the decode process.
       */
      public String decode(String value) throws DecoderException {
          if (value == null) {
              return null;
          }
          try {
              return decodeText(value);
          } catch (UnsupportedEncodingException e) {
              throw new DecoderException(e.getMessage(), e);
          }
      }
  
      /**
       * Encodes an object into its Base64 form using the default charset. Unsafe characters are escaped.
       * 
       * @param value
       *                  object to convert to Base64 form
       * @return Base64 object
       * 
       * @throws EncoderException
       *                  thrown if a failure condition is encountered during the encoding process.
       */
      public Object encode(Object value) throws EncoderException {
          if (value == null) {
              return null;
          } else if (value instanceof String) {
              return encode((String) value);
          } else {
              throw new EncoderException("Objects of type " +
                    value.getClass().getName() +
                    " cannot be encoded using BCodec");
          }
      }
  
      /**
       * Decodes a Base64 object into its original form. Escaped characters are converted back to their original
       * representation.
       * 
       * @param value
       *                  Base64 object to convert into its original form
       * 
       * @return original object
       * 
       * @throws DecoderException
       *                  Thrown if the argument is not a <code>String</code>. Thrown if a failure condition is
       *                  encountered during the decode process.
       */
      public Object decode(Object value) throws DecoderException {
          if (value == null) {
              return null;
          } else if (value instanceof String) {
              return decode((String) value);
          } else {
              throw new DecoderException("Objects of type " +
                    value.getClass().getName() +
                    " cannot be decoded using BCodec");
          }
      }
  
      /**
       * The default charset used for string decoding and encoding.
       * 
       * @return the default string charset.
       */
      public String getDefaultCharset() {
          return this.charset;
      }
  }
  