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 018package org.apache.log4j.pattern; 019 020import org.apache.log4j.spi.LoggingEvent; 021 022 023/** 024 * LoggingEventPatternConverter is a base class for pattern converters 025 * that can format information from instances of LoggingEvent. 026 * 027 * @author Curt Arnold 028 * 029 */ 030public abstract class LoggingEventPatternConverter extends PatternConverter { 031 /** 032 * Constructs an instance of LoggingEventPatternConverter. 033 * @param name name of converter. 034 * @param style CSS style for output. 035 */ 036 protected LoggingEventPatternConverter( 037 final String name, final String style) { 038 super(name, style); 039 } 040 041 /** 042 * Formats an event into a string buffer. 043 * @param event event to format, may not be null. 044 * @param toAppendTo string buffer to which the formatted event will be appended. May not be null. 045 */ 046 public abstract void format( 047 final LoggingEvent event, final StringBuffer toAppendTo); 048 049 /** 050 * {@inheritDoc} 051 */ 052 public void format(final Object obj, final StringBuffer output) { 053 if (obj instanceof LoggingEvent) { 054 format((LoggingEvent) obj, output); 055 } 056 } 057 058 /** 059 * Normally pattern converters are not meant to handle Exceptions although 060 * few pattern converters might. 061 * 062 * By examining the return values for this method, the containing layout will 063 * determine whether it handles throwables or not. 064 065 * @return true if this PatternConverter handles throwables 066 */ 067 public boolean handlesThrowable() { 068 return false; 069 } 070}