001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.io.input;
018
019/**
020 * Listener for events from a {@link Tailer}.
021 *
022 * @version $Id: TailerListener.java 1304052 2012-03-22 20:55:29Z ggregory $
023 * @since 2.0
024 */
025public interface TailerListener {
026
027    /**
028     * The tailer will call this method during construction,
029     * giving the listener a method of stopping the tailer.
030     * @param tailer the tailer.
031     */
032    void init(Tailer tailer);
033
034    /**
035     * This method is called if the tailed file is not found.
036     * <p>
037     * <b>Note:</b> this is called from the tailer thread.
038     */
039    void fileNotFound();
040
041    /**
042     * Called if a file rotation is detected.
043     *
044     * This method is called before the file is reopened, and fileNotFound may
045     * be called if the new file has not yet been created.
046     * <p>
047     * <b>Note:</b> this is called from the tailer thread.
048     */
049    void fileRotated();
050
051    /**
052     * Handles a line from a Tailer.
053     * <p>
054     * <b>Note:</b> this is called from the tailer thread.
055     * @param line the line.
056     */
057    void handle(String line);
058
059    /**
060     * Handles an Exception .
061     * <p>
062     * <b>Note:</b> this is called from the tailer thread.
063     * @param ex the exception.
064     */
065    void handle(Exception ex);
066
067}