1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache license, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the license for the specific language governing permissions and 15 * limitations under the license. 16 */ 17 package org.apache.logging.log4j.core.lookup; 18 19 import org.apache.logging.log4j.core.LogEvent; 20 import org.apache.logging.log4j.core.config.plugins.Plugin; 21 import org.apache.logging.log4j.message.MapMessage; 22 23 import java.util.Map; 24 25 /** 26 * The basis for a lookup based on a Map. 27 * @param <V> The type of object contained in the Map. 28 */ 29 @Plugin(name = "map", type = "Lookup") 30 public class MapLookup<V> implements StrLookup<V> { 31 /** 32 * Map keys are variable names and value. 33 */ 34 private final Map<String, V> map; 35 36 /** 37 * Creates a new instance backed by a Map. Used by the default lookup. 38 * 39 * @param map the map of keys to values, may be null 40 */ 41 public MapLookup(Map<String, V> map) { 42 this.map = map; 43 } 44 45 /** 46 * Constructor when used directly as a plugin. 47 */ 48 public MapLookup() { 49 this.map = null; 50 } 51 52 /** 53 * Looks up a String key to a String value using the map. 54 * <p/> 55 * If the map is null, then null is returned. 56 * The map result object is converted to a string using toString(). 57 * 58 * @param key the key to be looked up, may be null 59 * @return the matching value, null if no match 60 */ 61 public String lookup(String key) { 62 if (map == null) { 63 return null; 64 } 65 Object obj = map.get(key); 66 if (obj == null) { 67 return null; 68 } 69 return obj.toString(); 70 } 71 72 public String lookup(LogEvent event, String key) { 73 if (map == null && !(event.getMessage() instanceof MapMessage)) { 74 return null; 75 } 76 if (map != null && map.containsKey(key)) { 77 Object obj = map.get(key); 78 if (obj != null) { 79 return obj.toString(); 80 } 81 } 82 if (event.getMessage() instanceof MapMessage) { 83 return ((MapMessage) event.getMessage()).get(key); 84 } 85 return null; 86 } 87 }