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    1   /*
    2    * Copyright 2009 Red Hat, Inc.
    3    *
    4    * Red Hat licenses this file to you under the Apache License, version 2.0
    5    * (the "License"); you may not use this file except in compliance with the
    6    * License.  You may obtain a copy of the License at:
    7    *
    8    *    http://www.apache.org/licenses/LICENSE-2.0
    9    *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
    12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
    13   * License for the specific language governing permissions and limitations
    14   * under the License.
    15   */
    16  package org.jboss.netty.handler.codec.base64;
    17
    18  import org.jboss.netty.buffer.ChannelBuffer;
    19  import org.jboss.netty.buffer.ChannelBuffers;
    20  import org.jboss.netty.channel.Channel;
    21  import org.jboss.netty.channel.ChannelHandlerContext;
    22  import org.jboss.netty.channel.ChannelPipeline;
    23  import org.jboss.netty.channel.ChannelHandler.Sharable;
    24  import org.jboss.netty.handler.codec.frame.DelimiterBasedFrameDecoder;
    25  import org.jboss.netty.handler.codec.frame.Delimiters;
    26  import org.jboss.netty.handler.codec.frame.FrameDecoder;
    27  import org.jboss.netty.handler.codec.oneone.OneToOneDecoder;
    28  import org.jboss.netty.util.CharsetUtil;
    29
    30  /**
    31   * Decodes a Base64-encoded {@link ChannelBuffer} or US-ASCII {@link String}
    32   * into a {@link ChannelBuffer}.  Please note that this decoder must be used
    33   * with a proper {@link FrameDecoder} such as {@link DelimiterBasedFrameDecoder}
    34   * if you are using a stream-based transport such as TCP/IP.  A typical decoder
    35   * setup for TCP/IP would be:
    36   * <pre>
    37   * {@link ChannelPipeline} pipeline = ...;
    38   *
    39   * // Decoders
    40   * pipeline.addLast("frameDecoder", new {@link DelimiterBasedFrameDecoder}(80, {@link Delimiters#nulDelimiter()}));
    41   * pipeline.addLast("base64Decoder", new {@link Base64Decoder}());
    42   *
    43   * // Encoder
    44   * pipeline.addLast("base64Encoder", new {@link Base64Encoder}());
    45   * </pre>
    46   *
    47   * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
    48   * @author <a href="http://gleamynode.net/">Trustin Lee</a>
    49   * @version $Rev: 2241 $, $Date: 2010-04-16 13:12:43 +0900 (Fri, 16 Apr 2010) $
    50   *
    51   * @apiviz.landmark
    52   * @apiviz.uses org.jboss.netty.handler.codec.base64.Base64
    53   */
    54  @Sharable
    55  public class Base64Decoder extends OneToOneDecoder {
    56
    57      private final Base64Dialect dialect;
    58
    59      public Base64Decoder() {
    60          this(Base64Dialect.STANDARD);
    61      }
    62
    63      public Base64Decoder(Base64Dialect dialect) {
    64          if (dialect == null) {
    65              throw new NullPointerException("dialect");
    66          }
    67          this.dialect = dialect;
    68      }
    69
    70      @Override
    71      protected Object decode(ChannelHandlerContext ctx, Channel channel, Object msg)
    72              throws Exception {
    73          if (msg instanceof String) {
    74              msg = ChannelBuffers.copiedBuffer((String) msg, CharsetUtil.US_ASCII);
    75          } else if (!(msg instanceof ChannelBuffer)) {
    76              return msg;
    77          }
    78
    79          ChannelBuffer src = (ChannelBuffer) msg;
    80          return Base64.decode(
    81                  src, src.readerIndex(), src.readableBytes(), dialect);
    82      }
    83
    84  }