Home | History | Annotate | Download | only in log4j 
      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 Gülcü
     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      * Get the name of this appender. The name uniquely identifies the
     74      * appender.
     75      */
     76     public String getName();
     77 
     78     /**
     79      * Set the {@link ErrorHandler} for this appender.
     80      *
     81      * @since 0.9.0
     82      */
     83     public void setErrorHandler(ErrorHandler errorHandler);
     84 
     85     /**
     86      * Returns the {@link ErrorHandler} for this appender.
     87      *
     88      * @since 1.1
     89      */
     90     public ErrorHandler getErrorHandler();
     91 
     92     /**
     93      * Set the {@link Layout} for this appender.
     94      *
     95      * @since 0.8.1
     96      */
     97     public void setLayout(Layout layout);
     98 
     99     /**
    100      * Returns this appenders layout.
    101      *
    102      * @since 1.1
    103      */
    104     public Layout getLayout();
    105 
    106     /**
    107      * Set the name of this appender. The name is used by other
    108      * components to identify this appender.
    109      *
    110      * @since 0.8.1
    111      */
    112     public void setName(String name);
    113 
    114     /**
    115      * Configurators call this method to determine if the appender
    116      * requires a layout. If this method returns <code>true</code>,
    117      * meaning that layout is required, then the configurator will
    118      * configure an layout using the configuration information at its
    119      * disposal.  If this method returns <code>false</code>, meaning that
    120      * a layout is not required, then layout configuration will be
    121      * skipped even if there is available layout configuration
    122      * information at the disposal of the configurator..
    123      * <p/>
    124      * <p>In the rather exceptional case, where the appender
    125      * implementation admits a layout but can also work without it, then
    126      * the appender should return <code>true</code>.
    127      *
    128      * @since 0.8.4
    129      */
    130     public boolean requiresLayout();
    131 }
    132