    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.core.LogEvent;
    020    import org.apache.logging.log4j.core.config.plugins.Plugin;
    021    import org.apache.logging.log4j.message.StructuredDataMessage;
    022
    023    /**
    024     * Looks up keys from {@link org.apache.logging.log4j.message.StructuredDataMessage} log messages.
    025     */
    026    @Plugin(name = "sd", category = StrLookup.CATEGORY)
    027    public class StructuredDataLookup implements StrLookup {
    028
    029        /**
    030         * Returns {@code null}. This Lookup plugin does not make sense outside the context of a LogEvent.
    031         * @param key  the key to be looked up, may be null
    032         * @return {@code null}
    033         */
    034        @Override
    035        public String lookup(final String key) {
    036            return null;
    037        }
    038
    039        /**
    040         * Looks up the value for the key using the data in the LogEvent.
    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            if (event == null || !(event.getMessage() instanceof StructuredDataMessage)) {
    048                return null;
    049            }
    050            final StructuredDataMessage msg = (StructuredDataMessage) event.getMessage();
    051            if (key.equalsIgnoreCase("id")) {
    052                return msg.getId().getName();
    053            } else if (key.equalsIgnoreCase("type")) {
    054                return msg.getType();
    055            }
    056            return msg.get(key);
    057        }
    058    }