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Commons Beanutils example source code file (DynaBeanMapDecorator.java)

This example Commons Beanutils source code file (DynaBeanMapDecorator.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Commons Beanutils tags/keywords

dynabean, dynabeanmapdecorator, dynaclass, dynaproperty, dynaproperty, map, mapentry, object, object, set, string, string, unsupportedoperationexception, unsupportedoperationexception, util

The Commons Beanutils DynaBeanMapDecorator.java source code

/*
 * 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;

import java.util.Map;
import java.util.List;
import java.util.ArrayList;
import java.util.Set;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Collection;
import java.util.Collections;

/**
 * <p>Decorates a {@link DynaBean} to provide Map behaviour.

* * <p>The motivation for this implementation is to provide access to {@link DynaBean} * properties in technologies that are unaware of BeanUtils and {@link DynaBean}s - * such as the expression languages of JSTL and JSF.</p> * * <p>This can be achieved either by wrapping the {@link DynaBean} prior to * providing it to the technolody to process or by providing a <code>Map * accessor method on the DynaBean implementation: * <pre> * public Map getMap() { * return new DynaBeanMapDecorator(this); * }</code>
* </ul> * </p> * * <p>This, for example, could be used in JSTL in the following way to access * a DynaBean's <code>fooProperty: * <ul>
  • ${myDynaBean.map.fooProperty}
  • * </p> * * <h3>Usage * * <p>To decorate a {@link DynaBean} simply instantiate this class with the * target {@link DynaBean}:</p> * * <ul>
  • Map fooMap = new DynaBeanMapDecorator(fooDynaBean);
  • * * <p>The above example creates a read only Map. * To create a <code>Map which can be modified, construct a * <code>DynaBeanMapDecorator with the read only * attribute set to <code>false:

    * * <ul>
  • Map fooMap = new DynaBeanMapDecorator(fooDynaBean, false);
  • * * <h3>Limitations * <p>In this implementation the entrySet(), keySet() * and <code>values() methods create an unmodifiable * <code>Set and it does not support the Map's clear() * and <code>remove() operations.

    * * @since BeanUtils 1.8.0 * @version $Revision: 546471 $ $Date: 2007-06-12 13:57:20 +0100 (Tue, 12 Jun 2007) $ */ public class DynaBeanMapDecorator implements Map { private DynaBean dynaBean; private boolean readOnly; private transient Set keySet; // ------------------- Constructors ---------------------------------- /** * Constructs a read only Map for the specified * {@link DynaBean}. * * @param dynaBean The dyna bean being decorated * @throws IllegalArgumentException if the {@link DynaBean} is null. */ public DynaBeanMapDecorator(DynaBean dynaBean) { this(dynaBean, true); } /** * Construct a Map for the specified {@link DynaBean}. * * @param dynaBean The dyna bean being decorated * @param readOnly <code>true if the Mpa is read only * otherwise <code>false * @throws IllegalArgumentException if the {@link DynaBean} is null. */ public DynaBeanMapDecorator(DynaBean dynaBean, boolean readOnly) { if (dynaBean == null) { throw new IllegalArgumentException("DynaBean is null"); } this.dynaBean = dynaBean; this.readOnly = readOnly; } // ------------------- public Methods -------------------------------- /** * Indicate whether the Map is read only. * * @return <code>true if the Map is read only, * otherwise <code>false. */ public boolean isReadOnly() { return readOnly; } // ------------------- java.util.Map Methods ------------------------- /** * clear() operation is not supported. * * @throws UnsupportedOperationException */ public void clear() { throw new UnsupportedOperationException(); } /** * Indicate whether the {@link DynaBean} contains a specified * value for one (or more) of its properties. * * @param key The {@link DynaBean}'s property name * @return <code>true if one of the {@link DynaBean}'s * properties contains a specified value. */ public boolean containsKey(Object key) { DynaClass dynaClass = getDynaBean().getDynaClass(); DynaProperty dynaProperty = dynaClass.getDynaProperty(toString(key)); return (dynaProperty == null ? false : true); } /** * Indicates whether the decorated {@link DynaBean} contains * a specified value. * * @param value The value to check for. * @return <code>true if one of the the {@link DynaBean}'s * properties contains the specified value, otherwise * <code>false. */ public boolean containsValue(Object value) { DynaProperty[] properties = getDynaProperties(); for (int i = 0; i < properties.length; i++) { String key = properties[i].getName(); Object prop = getDynaBean().get(key); if (value == null) { if (prop == null) { return true; } } else { if (value.equals(prop)) { return true; } } } return false; } /** * <p>Returns the Set of the property/value mappings * in the decorated {@link DynaBean}.</p> * * <p>Each element in the Set is a Map.Entry * type.</p> * * @return An unmodifiable set of the DynaBean * property name/value pairs */ public Set entrySet() { DynaProperty[] properties = getDynaProperties(); Set set = new HashSet(properties.length); for (int i = 0; i < properties.length; i++) { String key = properties[i].getName(); Object value = getDynaBean().get(key); set.add(new MapEntry(key, value)); } return Collections.unmodifiableSet(set); } /** * Return the value for the specified key from * the decorated {@link DynaBean}. * * @param key The {@link DynaBean}'s property name * @return The value for the specified property. */ public Object get(Object key) { return getDynaBean().get(toString(key)); } /** * Indicate whether the decorated {@link DynaBean} has * any properties. * * @return <code>true if the {@link DynaBean} has * no properties, otherwise <code>false. */ public boolean isEmpty() { return (getDynaProperties().length == 0); } /** * <p>Returns the Set of the property * names in the decorated {@link DynaBean}.</p> * * <p>N.B.For {@link DynaBean}s whose associated {@link DynaClass} * is a {@link MutableDynaClass} a new Set is created every * time, otherwise the Set is created only once and cached.</p> * * @return An unmodifiable set of the {@link DynaBean}s * property names. */ public Set keySet() { if (keySet != null) { return keySet; } // Create a Set of the keys DynaProperty[] properties = getDynaProperties(); Set set = new HashSet(properties.length); for (int i = 0; i < properties.length; i++) { set.add(properties[i].getName()); } set = Collections.unmodifiableSet(set); // Cache the keySet if Not a MutableDynaClass DynaClass dynaClass = getDynaBean().getDynaClass(); if (!(dynaClass instanceof MutableDynaClass)) { keySet = set; } return set; } /** * Set the value for the specified property in * the decorated {@link DynaBean}. * * @param key The {@link DynaBean}'s property name * @param value The value for the specified property. * @return The previous property's value. * @throws UnsupportedOperationException if * <code>isReadOnly() is true. */ public Object put(Object key, Object value) { if (isReadOnly()) { throw new UnsupportedOperationException("Map is read only"); } String property = toString(key); Object previous = getDynaBean().get(property); getDynaBean().set(property, value); return previous; } /** * Copy the contents of a Map to the decorated {@link DynaBean}. * * @param map The Map of values to copy. * @throws UnsupportedOperationException if * <code>isReadOnly() is true. */ public void putAll(Map map) { if (isReadOnly()) { throw new UnsupportedOperationException("Map is read only"); } Iterator keys = map.keySet().iterator(); while (keys.hasNext()) { Object key = keys.next(); put(key, map.get(key)); } } /** * remove() operation is not supported. * * @param key The {@link DynaBean}'s property name * @return the value removed * @throws UnsupportedOperationException */ public Object remove(Object key) { throw new UnsupportedOperationException(); } /** * Returns the number properties in the decorated * {@link DynaBean}. * @return The number of properties. */ public int size() { return getDynaProperties().length; } /** * Returns the set of property values in the * decorated {@link DynaBean}. * * @return Unmodifiable collection of values. */ public Collection values() { DynaProperty[] properties = getDynaProperties(); List values = new ArrayList(properties.length); for (int i = 0; i < properties.length; i++) { String key = properties[i].getName(); Object value = getDynaBean().get(key); values.add(value); } return Collections.unmodifiableList(values); } // ------------------- protected Methods ----------------------------- /** * Provide access to the underlying {@link DynaBean} * this Map decorates. * * @return the decorated {@link DynaBean}. */ public DynaBean getDynaBean() { return dynaBean; } // ------------------- private Methods ------------------------------- /** * Convenience method to retrieve the {@link DynaProperty}s * for this {@link DynaClass}. * * @return The an array of the {@link DynaProperty}s. */ private DynaProperty[] getDynaProperties() { return getDynaBean().getDynaClass().getDynaProperties(); } /** * Convenience method to convert an Object * to a String. * * @param obj The Object to convert * @return String representation of the object */ private String toString(Object obj) { return (obj == null ? null : obj.toString()); } /** * Map.Entry implementation. */ private static class MapEntry implements Map.Entry { private Object key; private Object value; MapEntry(Object key, Object value) { this.key = key; this.value = value; } public boolean equals(Object o) { if (!(o instanceof Map.Entry)) { return false; } Map.Entry e = (Map.Entry)o; return ((key.equals(e.getKey())) && (value == null ? e.getValue() == null : value.equals(e.getValue()))); } public int hashCode() { return key.hashCode() + (value == null ? 0 : value.hashCode()); } public Object getKey() { return key; } public Object getValue() { return value; } public Object setValue(Object value) { throw new UnsupportedOperationException(); } } }

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