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