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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.util;
21  
22  /**
23   * Monitors uncaught exceptions.  {@link #exceptionCaught(Throwable)} is
24   * invoked when there are any uncaught exceptions.
25   * <p>
26   * You can monitor any uncaught exceptions by setting {@link ExceptionMonitor}
27   * by calling {@link #setInstance(ExceptionMonitor)}.  The default
28   * monitor logs all caught exceptions in <tt>WARN</tt> level using
29   * SLF4J.
30   *
31   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
32   *
33   * @see DefaultExceptionMonitor
34   */
35  public abstract class ExceptionMonitor {
36      private static ExceptionMonitor instance = new DefaultExceptionMonitor();
37  
38      /**
39       * Returns the current exception monitor.
40       */
41      public static ExceptionMonitor getInstance() {
42          return instance;
43      }
44  
45      /**
46       * Sets the uncaught exception monitor.  If <code>null</code> is specified,
47       * the default monitor will be set.
48       *
49       * @param monitor A new instance of {@link DefaultExceptionMonitor} is set
50       *                if <tt>null</tt> is specified.
51       */
52      public static void setInstance(ExceptionMonitor monitor) {
53          if (monitor == null) {
54              monitor = new DefaultExceptionMonitor();
55          }
56  
57          instance = monitor;
58      }
59  
60      /**
61       * Invoked when there are any uncaught exceptions.
62       * 
63       * @param cause The caught exception
64       */
65      public abstract void exceptionCaught(Throwable cause);
66  }