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; 019import java.lang.reflect.InvocationTargetException; 020import org.apache.commons.jexl3.JexlException; 021 022/** 023 * Specialized executor to get a property from an object. 024 * @since 2.0 025 */ 026public final class PropertyGetExecutor extends AbstractExecutor.Get { 027 /** A static signature for method(). */ 028 private static final Object[] EMPTY_PARAMS = {}; 029 /** The property. */ 030 private final String property; 031 032 /** 033 * Discovers a PropertyGetExecutor. 034 * <p>The method to be found should be named "get{P,p}property.</p> 035 * 036 * @param is the introspector 037 * @param clazz the class to find the get method from 038 * @param property the property name to find 039 * @return the executor if found, null otherwise 040 */ 041 public static PropertyGetExecutor discover(final Introspector is, final Class<?> clazz, final String property) { 042 final java.lang.reflect.Method method = discoverGet(is, "get", clazz, property); 043 return method == null? null : new PropertyGetExecutor(clazz, method, property); 044 } 045 046 /** 047 * Creates an instance. 048 * @param clazz he class the get method applies to 049 * @param method the method held by this executor 050 * @param identifier the property to get 051 */ 052 private PropertyGetExecutor(final Class<?> clazz, final java.lang.reflect.Method method, final String identifier) { 053 super(clazz, method); 054 property = identifier; 055 } 056 057 @Override 058 public Object getTargetProperty() { 059 return property; 060 } 061 062 @Override 063 public Object invoke(final Object o) throws IllegalAccessException, InvocationTargetException { 064 return method == null ? null : method.invoke(o, (Object[]) null); 065 } 066 067 @Override 068 public Object tryInvoke(final Object o, final Object identifier) { 069 if (o != null && method != null 070 && property.equals(castString(identifier)) 071 && objectClass.equals(o.getClass())) { 072 try { 073 return method.invoke(o, (Object[]) null); 074 } catch (IllegalAccessException | IllegalArgumentException xill) { 075 return TRY_FAILED;// fail 076 } catch (final InvocationTargetException xinvoke) { 077 throw JexlException.tryFailed(xinvoke); // throw 078 } 079 } 080 return TRY_FAILED; 081 } 082 083 /** 084 * Base method for boolean and object property get. 085 * @param is the introspector 086 * @param which "is" or "get" for boolean or object 087 * @param clazz The class being examined. 088 * @param property The property being addressed. 089 * @return The {get,is}{p,P}roperty method if one exists, null otherwise. 090 */ 091 static java.lang.reflect.Method discoverGet(final Introspector is, 092 final String which, 093 final Class<?> clazz, 094 final String property) { 095 if (property == null || property.isEmpty()) { 096 return null; 097 } 098 // this is gross and linear, but it keeps it straightforward. 099 java.lang.reflect.Method method; 100 final int start = which.length(); // "get" or "is" so 3 or 2 for char case switch 101 // start with get<Property> 102 final StringBuilder sb = new StringBuilder(which); 103 sb.append(property); 104 // uppercase nth char 105 final char c = sb.charAt(start); 106 sb.setCharAt(start, Character.toUpperCase(c)); 107 method = is.getMethod(clazz, sb.toString(), EMPTY_PARAMS); 108 //lowercase nth char 109 if (method == null) { 110 sb.setCharAt(start, Character.toLowerCase(c)); 111 method = is.getMethod(clazz, sb.toString(), EMPTY_PARAMS); 112 } 113 return method; 114 } 115} 116