/* * Copyright 1999-2005 The Apache Software Foundation. *  * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at *  *      http://www.apache.org/licenses/LICENSE-2.0 *  * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package org.apache.log4j.spi;import org.apache.log4j.Appender;import org.apache.log4j.Logger;/**   Appenders may delegate their error handling to   <code>ErrorHandlers</code>.   <p>Error handling is a particularly tedious to get right because by   definition errors are hard to predict and to reproduce.    <p>Please take the time to contact the author in case you discover   that errors are not properly handled. You are most welcome to   suggest new error handling policies or criticize existing policies.   @author Ceki G&uuml;lc&uuml;   */public interface ErrorHandler extends OptionHandler {  /**     Add a reference to a logger to which the failing appender might     be attached to. The failing appender will be searched and     replaced only in the loggers you add through this method.     @param logger One of the loggers that will be searched for the failing     appender in view of replacement.          @since 1.2 */  void setLogger(Logger logger);  /**     Equivalent to the {@link #error(String, Exception, int,     LoggingEvent event)} with the the event parameteter set to     <code>null</code>.       */  void error(String message, Exception e, int errorCode);  /**     This method is normally used to just print the error message     passed as a parameter.         */  void error(String message);  /**     This method is invoked to handle the error.     @param message The message assoicated with the error.     @param e The Exption that was thrown when the error occured.     @param errorCode The error code associated with the error.      @param event The logging event that the failing appender is asked            to log.     @since 1.2 */  void error(String message, Exception e, int errorCode, LoggingEvent event);    /**     Set the appender for which errors are handled. This method is     usually called when the error handler is configured.          @since 1.2 */  void setAppender(Appender appender);  /**     Set the appender to falkback upon in case of failure.          @since 1.2 */  void setBackupAppender(Appender appender);}