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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  }