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 */ 017 package org.apache.log4j.spi; 018 019 import org.apache.log4j.Appender; 020 import org.apache.log4j.Logger; 021 022 023 /** 024 * Appenders may delegate their error handling to 025 * <code>ErrorHandlers</code>. 026 * <p/> 027 * <p>Error handling is a particularly tedious to get right because by 028 * definition errors are hard to predict and to reproduce. 029 * <p/> 030 * <p/> 031 * <p>Please take the time to contact the author in case you discover 032 * that errors are not properly handled. You are most welcome to 033 * suggest new error handling policies or criticize existing policies. 034 * 035 * @author Ceki Gülcü 036 */ 037 public interface ErrorHandler { 038 039 /** 040 * Add a reference to a logger to which the failing appender might 041 * be attached to. The failing appender will be searched and 042 * replaced only in the loggers you add through this method. 043 * 044 * @param logger One of the loggers that will be searched for the failing 045 * appender in view of replacement. 046 * @since 1.2 047 */ 048 void setLogger(Logger logger); 049 050 051 /** 052 * Equivalent to the {@link #error(String, Exception, int, 053 * LoggingEvent event)} with the the event parameteter set to 054 * <code>null</code>. 055 */ 056 void error(String message, Exception e, int errorCode); 057 058 /** 059 * This method is normally used to just print the error message 060 * passed as a parameter. 061 */ 062 void error(String message); 063 064 /** 065 * This method is invoked to handle the error. 066 * 067 * @param message The message assoicated with the error. 068 * @param e The Exption that was thrown when the error occured. 069 * @param errorCode The error code associated with the error. 070 * @param event The logging event that the failing appender is asked 071 * to log. 072 * @since 1.2 073 */ 074 void error(String message, Exception e, int errorCode, LoggingEvent event); 075 076 /** 077 * Set the appender for which errors are handled. This method is 078 * usually called when the error handler is configured. 079 * 080 * @since 1.2 081 */ 082 void setAppender(Appender appender); 083 084 /** 085 * Set the appender to falkback upon in case of failure. 086 * 087 * @since 1.2 088 */ 089 void setBackupAppender(Appender appender); 090 } 091