Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.commons.beanutils.expression; /** * Property Name Expression Resolver. * <p> * Methods such as PropertyUtilsBean's <code>setNestedProperty()</code> method * use a <code>Resolver</code> to process a <i>property name</i> * expression and resolve <i>nested</i>, <i>indexed</i> and <i>mapped</i> * property names. The following code provides an example usage * demonstrating all the methods: * * <pre> * // Iterate through a nested property expression * while (resolver.hasNested(name)) { * * // isolate a single property from a nested expresion * String next = resolver.next(name); * * // Process... * String property = resolver.getProperty(next); * if (resolver.isIndexed(next)) { * * int index = resolver.getIndex(next); * bean = getIndexedProperty(bean, property, index); * * } else if (resolver.isMapped(next)) { * * String key = resolver.getKey(next); * bean = getMappedProperty(bean, property, key); * * } else { * * bean = getSimpleProperty(bean, property); * * } * * // remove the processed property from the expression * name = resolver.remove(name); * } * </pre> * * In order to create an implementation, it is important to understand how * BeanUtils/PropertyUtils uses the <code>resolver</code>. The following are * the main methods that use it: * <ul> * <li>{@link org.apache.commons.beanutils.PropertyUtilsBean}</li> * <ul> * <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#getIndexedProperty(Object, String)}</li> * <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#getMappedProperty(Object, String)}</li> * <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#getNestedProperty(Object, String)}</li> * <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#getPropertyDescriptor(Object, String)}</li> * <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#getSimpleProperty(Object, String)}</li> * <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#setIndexedProperty(Object, String, Object)}</li> * <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#setMappedProperty(Object, String, Object)}</li> * <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#setNestedProperty(Object, String, Object)}</li> * <li>{@link org.apache.commons.beanutils.PropertyUtilsBean#setSimpleProperty(Object, String, Object)}</li> * </ul> * <li>{@link org.apache.commons.beanutils.BeanUtilsBean}</li> * <ul> * <li>{@link org.apache.commons.beanutils.BeanUtilsBean#copyProperty(Object, String, Object)}</li> * <li>{@link org.apache.commons.beanutils.BeanUtilsBean#setProperty(Object, String, Object)}</li> * </ul> * <li>{@link org.apache.commons.beanutils.locale.LocaleBeanUtilsBean}</li> * <ul> * <li>{@link org.apache.commons.beanutils.locale.LocaleBeanUtilsBean#setProperty(Object, * String, Object, String)}</li> * </ul> * </ul> * * @version $Revision: 555845 $ $Date: 2007-07-13 03:52:05 +0100 (Fri, 13 Jul 2007) $ * @see org.apache.commons.beanutils.PropertyUtilsBean#setResolver(Resolver) * @since 1.8.0 */ public interface Resolver { /** * Extract the index value from the property expression or -1. * * @param expression The property expression * @return The index value or -1 if the property is not indexed * @throws IllegalArgumentException If the indexed property is illegally * formed or has an invalid (non-numeric) value */ int getIndex(String expression); /** * Extract the map key from the property expression or <code>null</code>. * * @param expression The property expression * @return The index value * @throws IllegalArgumentException If the mapped property is illegally formed */ String getKey(String expression); /** * Return the property name from the property expression. * * @param expression The property expression * @return The property name */ String getProperty(String expression); /** * Indicates whether or not the expression * contains nested property expressions or not. * * @param expression The property expression * @return The next property expression */ boolean hasNested(String expression); /** * Indicate whether the expression is for an indexed property or not. * * @param expression The property expression * @return <code>true</code> if the expresion is indexed, * otherwise <code>false</code> */ boolean isIndexed(String expression); /** * Indicate whether the expression is for a mapped property or not. * * @param expression The property expression * @return <code>true</code> if the expresion is mapped, * otherwise <code>false</code> */ boolean isMapped(String expression); /** * Extract the next property expression from the * current expression. * * @param expression The property expression * @return The next property expression */ String next(String expression); /** * Remove the last property expresson from the * current expression. * * @param expression The property expression * @return The new expression value, with first property * expression removed - null if there are no more expressions */ String remove(String expression); }