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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.core.filterchain;
21  
22  import org.apache.mina.core.session.IoSession;
23  
24  /**
25   * An interface that builds {@link IoFilterChain} in predefined way
26   * when {@link IoSession} is created.  You can extract common filter chain
27   * modification logic to this interface.  For example, to add a filter
28   * to the chain,
29   * <pre>
30   * public class MyFilterChainBuilder implements IoFilterChainBuilder {
31   *     public void buildFilterChain( IoFilterChain chain ) throws Exception {
32   *         chain.addLast( "myFilter", new MyFilter() );
33   *     }
34   * }
35   * </pre>
36   *
37   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
38   */
39  public interface IoFilterChainBuilder {
40      /**
41       * An implementation which does nothing.
42       */
43      IoFilterChainBuilder NOOP = new IoFilterChainBuilder() {
44          public void buildFilterChain(IoFilterChain chain) throws Exception {
45          }
46  
47          @Override
48          public String toString() {
49              return "NOOP";
50          }
51      };
52  
53      /**
54       * Modifies the specified <tt>chain</tt>.
55       */
56      void buildFilterChain(IoFilterChain chain) throws Exception;
57  }