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.logging.log4j.core.pattern;
018    
019    import org.apache.logging.log4j.core.LogEvent;
020    import org.apache.logging.log4j.core.config.plugins.Plugin;
021    
022    
023    /**
024     * Formats the class name of the site of the logging request.
025     */
026    @Plugin(name = "ClassNamePatternConverter", category = PatternConverter.CATEGORY)
027    @ConverterKeys({ "C", "class" })
028    public final class ClassNamePatternConverter extends NamePatternConverter {
029    
030        private static final String NA = "?";
031    
032        /**
033         * Private constructor.
034         *
035         * @param options options, may be null.
036         */
037        private ClassNamePatternConverter(
038            final String[] options) {
039            super("Class Name", "class name", options);
040        }
041    
042        /**
043         * Gets an instance of ClassNamePatternConverter.
044         *
045         * @param options options, may be null.
046         * @return instance of pattern converter.
047         */
048        public static ClassNamePatternConverter newInstance(final String[] options) {
049            return new ClassNamePatternConverter(options);
050        }
051    
052        /**
053         * Format a logging event.
054         *
055         * @param event      event to format.
056         * @param toAppendTo string buffer to which class name will be appended.
057         */
058        @Override
059        public void format(final LogEvent event, final StringBuilder toAppendTo) {
060            final StackTraceElement element = event.getSource();
061            if (element == null) {
062                toAppendTo.append(NA);
063            } else {
064                toAppendTo.append(abbreviate(element.getClassName()));
065            }
066        }
067    }