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 018package org.apache.commons.jexl3.internal.introspection; 019 020import java.util.Map; 021 022/** 023 * Specialized executor to get a property from a Map. 024 * @since 2.0 025 */ 026public final class MapGetExecutor extends AbstractExecutor.Get { 027 /** The java.util.map.get method used as an active marker in MapGet. */ 028 private static final java.lang.reflect.Method MAP_GET = 029 initMarker(Map.class, "get", Object.class); 030 /** The property. */ 031 private final Object property; 032 033 /** 034 * Attempts to discover a MapGetExecutor. 035 * 036 * @param is the introspector 037 * @param clazz the class to find the get method from 038 * @param identifier the key to use as an argument to the get method 039 * @return the executor if found, null otherwise 040 */ 041 public static MapGetExecutor discover(final Introspector is, final Class<?> clazz, final Object identifier) { 042 if (Map.class.isAssignableFrom(clazz)) { 043 return new MapGetExecutor(clazz, MAP_GET, identifier); 044 } 045 return null; 046 } 047 048 /** 049 * Creates an instance. 050 * @param clazz he class the get method applies to 051 * @param method the method held by this executor 052 * @param key the property to get 053 */ 054 private MapGetExecutor(final Class<?> clazz, final java.lang.reflect.Method method, final Object key) { 055 super(clazz, method); 056 property = key; 057 } 058 059 @Override 060 public Object getTargetProperty() { 061 return property; 062 } 063 064 @Override 065 public Object invoke(final Object obj) { 066 @SuppressWarnings("unchecked") // ctor only allows Map instances - see discover() method 067 final Map<Object, ?> map = (Map<Object, ?>) obj; 068 return map.get(property); 069 } 070 071 @Override 072 public Object tryInvoke(final Object obj, final Object key) { 073 if (obj != null 074 && method != null 075 && objectClass.equals(obj.getClass()) 076 && ((property == null && key == null) 077 || (property != null && key != null && property.getClass().equals(key.getClass())))) { 078 @SuppressWarnings("unchecked") // ctor only allows Map instances - see discover() method 079 final Map<Object, ?> map = (Map<Object, ?>) obj; 080 return map.get(key); 081 } 082 return TRY_FAILED; 083 } 084}