Appender xref

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    1   /*
    2    * Copyright 2001-2004 The Apache Software Foundation.
    3    *
    4    * Licensed under the Apache License, Version 2.0 (the "License");
    5    * you may not use this file except in compliance with the License.
    6    * You may obtain a copy of the License at
    7    *
    8    *      http://www.apache.org/licenses/LICENSE-2.0
    9    *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS,
    12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   * See the License for the specific language governing permissions and
    14   * limitations under the License.
    15   */
    16
    17  package org.apache.log4j;
    18
    19  import org.apache.log4j.spi.Filter;
    20  import org.apache.log4j.spi.ErrorHandler;
    21  import org.apache.log4j.spi.Layout;
    22  import org.apache.log4j.spi.LoggingEvent;
    23
    24  /**
    25   * Implement this interface for your own strategies for outputting log
    26   * statements.
    27   *
    28   * @author Ceki G&uuml;lc&uuml;
    29   */
    30  public interface Appender {
    31
    32    /**
    33     * Add a filter to the end of the filter list.
    34     *
    35     * @since 0.9.0
    36     */
    37    void addFilter(Filter newFilter);
    38
    39    /**
    40     * Returns the head Filter. The Filters are organized in a linked list
    41     * and so all Filters on this Appender are available through the result.
    42     *
    43     * @return the head Filter or null, if no Filters are present
    44     * @since 1.1
    45     */
    46    public Filter getFilter();
    47
    48    /**
    49     * Clear the list of filters by removing all the filters in it.
    50     *
    51     * @since 0.9.0
    52     */
    53    public void clearFilters();
    54
    55    /**
    56     * Release any resources allocated within the appender such as file
    57     * handles, network connections, etc.
    58     * <p/>
    59     * <p>It is a programming error to append to a closed appender.
    60     *
    61     * @since 0.8.4
    62     */
    63    public void close();
    64
    65    /**
    66     * Log in <code>Appender</code> specific way. When appropriate,
    67     * Loggers will call the <code>doAppend</code> method of appender
    68     * implementations in order to log.
    69     */
    70    public void doAppend(LoggingEvent event);
    71
    72
    73    /**
    74     * Get the name of this appender. The name uniquely identifies the
    75     * appender.
    76     */
    77    public String getName();
    78
    79
    80    /**
    81     * Set the {@link ErrorHandler} for this appender.
    82     *
    83     * @since 0.9.0
    84     */
    85    public void setErrorHandler(ErrorHandler errorHandler);
    86
    87    /**
    88     * Returns the {@link ErrorHandler} for this appender.
    89     *
    90     * @since 1.1
    91     */
    92    public ErrorHandler getErrorHandler();
    93
    94    /**
    95     * Set the {@link Layout} for this appender.
    96     *
    97     * @since 0.8.1
    98     */
    99    public void setLayout(Layout layout);
    100
    101   /**
    102    * Returns this appenders layout.
    103    *
    104    * @since 1.1
    105    */
    106   public Layout getLayout();
    107
    108
    109   /**
    110    * Set the name of this appender. The name is used by other
    111    * components to identify this appender.
    112    *
    113    * @since 0.8.1
    114    */
    115   public void setName(String name);
    116
    117   /**
    118    * Configurators call this method to determine if the appender
    119    * requires a layout. If this method returns <code>true</code>,
    120    * meaning that layout is required, then the configurator will
    121    * configure an layout using the configuration information at its
    122    * disposal.  If this method returns <code>false</code>, meaning that
    123    * a layout is not required, then layout configuration will be
    124    * skipped even if there is available layout configuration
    125    * information at the disposal of the configurator..
    126    * <p/>
    127    * <p>In the rather exceptional case, where the appender
    128    * implementation admits a layout but can also work without it, then
    129    * the appender should return <code>true</code>.
    130    *
    131    * @since 0.8.4
    132    */
    133   public boolean requiresLayout();
    134 }