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.lookup;
018
019import org.apache.logging.log4j.ThreadContext;
020import org.apache.logging.log4j.core.LogEvent;
021import org.apache.logging.log4j.core.config.plugins.Plugin;
022
023/**
024 * Looks up keys from system properties.
025 */
026@Plugin(name = "ctx", category = "Lookup")
027public 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}