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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.handler.demux;
21  
22  import org.apache.mina.core.session.IoSession;
23  
24  /**
25   * A handler interface that {@link DemuxingIoHandler} forwards
26   * <code>exceptionCaught</code> events to.  You have to register your
27   * handler with the type of exception you want to get notified using
28   * {@link DemuxingIoHandler#addExceptionHandler(Class, ExceptionHandler)}.
29   *
30   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
31   */
32  public interface ExceptionHandler<E extends Throwable> {
33      /**
34       * A {@link ExceptionHandler} that does nothing.  This is useful when
35       * you want to ignore an exception of a specific type silently.
36       */
37      static ExceptionHandler<Throwable> NOOP = new ExceptionHandler<Throwable>() {
38          public void exceptionCaught(IoSession session, Throwable cause) {
39              // Do nothing
40          }
41      };
42  
43      /**
44       * A {@link ExceptionHandler} that closes the session immediately.
45       * This is useful when you want to close the session when an exception of
46       * a specific type is raised.
47       */
48      static ExceptionHandler<Throwable> CLOSE = new ExceptionHandler<Throwable>() {
49          public void exceptionCaught(IoSession session, Throwable cause) {
50              session.close(true);
51          }
52      };
53  
54      /**
55       * Invoked when the specific type of exception is caught from the
56       * specified <code>session</code>.
57       */
58      void exceptionCaught(IoSession session, E cause) throws Exception;
59  }