    001/*
    002 * Copyright 2001-2004 The Apache Software Foundation.
    003 *
    004 * Licensed under the Apache License, Version 2.0 (the "License");
    005 * you may not use this file except in compliance with the License.
    006 * You may obtain a copy of the License at
    007 *
    008 *      http://www.apache.org/licenses/LICENSE-2.0
    009 *
    010 * Unless required by applicable law or agreed to in writing, software
    011 * distributed under the License is distributed on an "AS IS" BASIS,
    012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    013 * See the License for the specific language governing permissions and
    014 * limitations under the License.
    015 */
    016
    017package org.apache.log4j;
    018
    019import org.apache.log4j.spi.Filter;
    020import org.apache.log4j.spi.ErrorHandler;
    021import org.apache.log4j.spi.LoggingEvent;
    022
    023/**
    024 * Implement this interface for your own strategies for outputting log
    025 * statements.
    026 *
    027 * @author Ceki G&uuml;lc&uuml;
    028 */
    029public interface Appender {
    030
    031    /**
    032     * Add a filter to the end of the filter list.
    033     *
    034     * @since 0.9.0
    035     */
    036    void addFilter(Filter newFilter);
    037
    038    /**
    039     * Returns the head Filter. The Filters are organized in a linked list
    040     * and so all Filters on this Appender are available through the result.
    041     *
    042     * @return the head Filter or null, if no Filters are present
    043     * @since 1.1
    044     */
    045    public Filter getFilter();
    046
    047    /**
    048     * Clear the list of filters by removing all the filters in it.
    049     *
    050     * @since 0.9.0
    051     */
    052    public void clearFilters();
    053
    054    /**
    055     * Release any resources allocated within the appender such as file
    056     * handles, network connections, etc.
    057     * <p/>
    058     * <p>It is a programming error to append to a closed appender.
    059     *
    060     * @since 0.8.4
    061     */
    062    public void close();
    063
    064    /**
    065     * Log in <code>Appender</code> specific way. When appropriate,
    066     * Loggers will call the <code>doAppend</code> method of appender
    067     * implementations in order to log.
    068     */
    069    public void doAppend(LoggingEvent event);
    070
    071    /**
    072     * Get the name of this appender. The name uniquely identifies the
    073     * appender.
    074     */
    075    public String getName();
    076
    077    /**
    078     * Set the {@link ErrorHandler} for this appender.
    079     *
    080     * @since 0.9.0
    081     */
    082    public void setErrorHandler(ErrorHandler errorHandler);
    083
    084    /**
    085     * Returns the {@link ErrorHandler} for this appender.
    086     *
    087     * @since 1.1
    088     */
    089    public ErrorHandler getErrorHandler();
    090
    091    /**
    092     * Set the {@link Layout} for this appender.
    093     *
    094     * @since 0.8.1
    095     */
    096    public void setLayout(Layout layout);
    097
    098    /**
    099     * Returns this appenders layout.
    100     *
    101     * @since 1.1
    102     */
    103    public Layout getLayout();
    104
    105    /**
    106     * Set the name of this appender. The name is used by other
    107     * components to identify this appender.
    108     *
    109     * @since 0.8.1
    110     */
    111    public void setName(String name);
    112
    113    /**
    114     * Configurators call this method to determine if the appender
    115     * requires a layout. If this method returns <code>true</code>,
    116     * meaning that layout is required, then the configurator will
    117     * configure an layout using the configuration information at its
    118     * disposal.  If this method returns <code>false</code>, meaning that
    119     * a layout is not required, then layout configuration will be
    120     * skipped even if there is available layout configuration
    121     * information at the disposal of the configurator.
    122     * <p/>
    123     * <p>In the rather exceptional case, where the appender
    124     * implementation admits a layout but can also work without it, then
    125     * the appender should return <code>true</code>.
    126     *
    127     * @since 0.8.4
    128     */
    129    public boolean requiresLayout();
    130}