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 */ 017package org.apache.logging.log4j.core.pattern; 018 019import org.apache.logging.log4j.core.LogEvent; 020 021/** 022 * LoggingEventPatternConverter is a base class for pattern converters 023 * that can format information from instances of LoggingEvent. 024 */ 025public abstract class LogEventPatternConverter extends AbstractPatternConverter { 026 027 /** 028 * Constructs an instance of LoggingEventPatternConverter. 029 * 030 * @param name name of converter. 031 * @param style CSS style for output. 032 */ 033 protected LogEventPatternConverter(final String name, final String style) { 034 super(name, style); 035 } 036 037 /** 038 * Formats an event into a string buffer. 039 * 040 * @param event event to format, may not be null. 041 * @param toAppendTo string buffer to which the formatted event will be appended. May not be null. 042 */ 043 public abstract void format(final LogEvent event, final StringBuilder toAppendTo); 044 045 /** 046 * {@inheritDoc} 047 */ 048 @Override 049 public void format(final Object obj, final StringBuilder output) { 050 if (obj instanceof LogEvent) { 051 format((LogEvent) obj, output); 052 } 053 } 054 055 /** 056 * Normally pattern converters are not meant to handle Exceptions although few pattern converters might. 057 * <p> 058 * By examining the return values for this method, the containing layout will determine whether it handles 059 * throwables or not. 060 * </p> 061 * 062 * @return true if this PatternConverter handles throwables 063 */ 064 public boolean handlesThrowable() { 065 return false; 066 } 067 068 public boolean isVariable() { 069 return true; 070 } 071}