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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  }