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1   /*
2    *  Licensed to the Apache Software Foundation (ASF) under one
3    *  or more contributor license agreements.  See the NOTICE file
4    *  distributed with this work for additional information
5    *  regarding copyright ownership.  The ASF licenses this file
6    *  to you under the Apache License, Version 2.0 (the
7    *  "License"); you may not use this file except in compliance
8    *  with the License.  You may obtain a copy of the License at
9    *
10   *    http://www.apache.org/licenses/LICENSE-2.0
11   *
12   *  Unless required by applicable law or agreed to in writing,
13   *  software distributed under the License is distributed on an
14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   *  KIND, either express or implied.  See the License for the
16   *  specific language governing permissions and limitations
17   *  under the License.
18   *
19   */
20  package org.apache.mina.example.tapedeck;
21  
22  import java.nio.charset.Charset;
23  import java.util.LinkedList;
24  
25  import org.apache.mina.core.buffer.IoBuffer;
26  import org.apache.mina.core.filterchain.IoFilter.NextFilter;
27  import org.apache.mina.core.session.IoSession;
28  import org.apache.mina.filter.codec.ProtocolDecoder;
29  import org.apache.mina.filter.codec.ProtocolDecoderOutput;
30  import org.apache.mina.filter.codec.textline.LineDelimiter;
31  import org.apache.mina.filter.codec.textline.TextLineDecoder;
32  
33  /**
34   * MINA {@link ProtocolDecoder} which decodes bytes into {@link Command}
35   * objects.
36   *
37   * @author The Apache MINA Project (dev@mina.apache.org)
38   * @version $Rev: 713125 $, $Date: 2008-11-11 20:32:26 +0100 (Tue, 11 Nov 2008) $
39   */
40  public class CommandDecoder extends TextLineDecoder {
41      
42      public CommandDecoder() {
43          super(Charset.forName("UTF8"), LineDelimiter.WINDOWS);
44      }
45      
46      private Object parseCommand(String line) throws CommandSyntaxException {
47          String[] temp = line.split(" +", 2);
48          String cmd = temp[0].toLowerCase();
49          String arg = temp.length > 1 ? temp[1] : null;
50          
51          if (LoadCommand.NAME.equals(cmd)) {
52              if (arg == null) {
53                  throw new CommandSyntaxException("No tape number specified");
54              }
55              try {
56                  return new LoadCommand(Integer.parseInt(arg));
57              } catch (NumberFormatException nfe) {
58                  throw new CommandSyntaxException("Illegal tape number: " + arg);
59              }
60          } else if (PlayCommand.NAME.equals(cmd)) {
61              return new PlayCommand();
62          } else if (PauseCommand.NAME.equals(cmd)) {
63              return new PauseCommand();
64          } else if (StopCommand.NAME.equals(cmd)) {
65              return new StopCommand();
66          } else if (ListCommand.NAME.equals(cmd)) {
67              return new ListCommand();
68          } else if (EjectCommand.NAME.equals(cmd)) {
69              return new EjectCommand();
70          } else if (QuitCommand.NAME.equals(cmd)) {
71              return new QuitCommand();
72          } else if (InfoCommand.NAME.equals(cmd)) {
73              return new InfoCommand();
74          } else if (UserCommand.NAME.equals(cmd)) {
75              if (arg == null) {
76                  throw new CommandSyntaxException("No username specified");
77              }
78              return new UserCommand(arg);
79          } else if (PasswordCommand.NAME.equals(cmd)) {
80              if (arg == null) {
81                  throw new CommandSyntaxException("No password specified");
82              }
83              return new PasswordCommand(arg);
84          }
85          
86          throw new CommandSyntaxException("Unknown command: " + cmd);
87      }
88  
89      @Override
90      public void decode(IoSession session, IoBuffer in, final ProtocolDecoderOutput out) 
91              throws Exception {
92          
93          final LinkedList<String> lines = new LinkedList<String>();
94          super.decode(session, in, new ProtocolDecoderOutput() {
95              public void write(Object message) {
96                  lines.add((String) message);
97              }
98              public void flush(NextFilter nextFilter, IoSession session) {}
99          });
100         
101         for (String s: lines) {
102             out.write(parseCommand(s));
103         }
104     }
105 
106 }