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.lookup;
018    
019    import org.apache.logging.log4j.ThreadContext;
020    import org.apache.logging.log4j.core.LogEvent;
021    import org.apache.logging.log4j.core.config.plugins.Plugin;
022    
023    /**
024     * Looks up keys from {@link ThreadContext} objects..
025     */
026    @Plugin(name = "ctx", category = StrLookup.CATEGORY)
027    public class ContextMapLookup implements StrLookup {
028    
029        /**
030         * Looks up the value from the ThreadContext Map.
031         * @param key  the key to be looked up, may be null
032         * @return The value associated with the key.
033         */
034        @Override
035        public String lookup(final String key) {
036            return ThreadContext.get(key);
037        }
038    
039        /**
040         * Looks up the value from the ThreadContext Map.
041         * @param event The current LogEvent.
042         * @param key  the key to be looked up, may be null
043         * @return The value associated with the key.
044         */
045        @Override
046        public String lookup(final LogEvent event, final String key) {
047            return event.getContextMap().get(key);
048        }
049    }