BaseDynaBeanMapDecorator.java
/*
* 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.beanutils2;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
/**
* <p>
* A base class for decorators providing {@code Map} behavior on {@link DynaBean}s.
* </p>
*
* <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 rather technical base class implements the methods of the {@code Map} interface on top of a {@code DynaBean}. It was introduced to handle generic
* parameters in a meaningful way without breaking backwards compatibility of the 1.x {@code DynaBeanMapDecorator} class: A map wrapping a {@code DynaBean}
* should be of type {@code Map<String, Object>}. However, when using these generic parameters in {@code DynaBeanMapDecorator} this would be an incompatible
* change (as method signatures would have to be adapted). To solve this problem, this generic base class is added which allows specifying the key type as
* parameter. This makes it easy to have a new subclass using the correct generic parameters while {@code DynaBeanMapDecorator} could still remain with
* compatible parameters.
* </p>
*
* @param <K> the type of the keys in the decorated map
* @since 1.9.0
*/
public abstract class BaseDynaBeanMapDecorator<K> implements Map<K, Object> {
/**
* Map.Entry implementation.
*/
private static final class MapEntry<K> implements Map.Entry<K, Object> {
private final K key;
private final Object value;
MapEntry(final K key, final Object value) {
this.key = key;
this.value = value;
}
@Override
public boolean equals(final Object obj) {
if (this == obj) {
return true;
}
if (!(obj instanceof Map.Entry)) {
return false;
}
final Map.Entry<?, ?> other = (Map.Entry<?, ?>) obj;
return Objects.equals(key, other.getKey()) && Objects.equals(value, other.getValue());
}
@Override
public K getKey() {
return key;
}
@Override
public Object getValue() {
return value;
}
@Override
public int hashCode() {
return Objects.hash(key, value);
}
@Override
public Object setValue(final Object value) {
throw new UnsupportedOperationException();
}
}
private final DynaBean dynaBean;
private final boolean readOnly;
private transient Set<K> keySet;
/**
* 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 BaseDynaBeanMapDecorator(final DynaBean dynaBean) {
this(dynaBean, true);
}
/**
* Constructs a Map for the specified {@link DynaBean}.
*
* @param dynaBean The dyna bean being decorated
* @param readOnly {@code true} if the Map is read only otherwise {@code false}
* @throws IllegalArgumentException if the {@link DynaBean} is null.
*/
public BaseDynaBeanMapDecorator(final DynaBean dynaBean, final boolean readOnly) {
this.dynaBean = Objects.requireNonNull(dynaBean, "dynaBean");
this.readOnly = readOnly;
}
/**
* clear() operation is not supported.
*
* @throws UnsupportedOperationException This operation is not yet supported
*/
@Override
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.
*/
@Override
public boolean containsKey(final Object key) {
final DynaClass dynaClass = getDynaBean().getDynaClass();
final DynaProperty dynaProperty = dynaClass.getDynaProperty(toString(key));
return dynaProperty != null;
}
/**
* Indicates whether the decorated {@link DynaBean} contains a specified value.
*
* @param value The value to check for.
* @return {@code true} if one of the {@link DynaBean}'s properties contains the specified value, otherwise {@code false}.
*/
@Override
public boolean containsValue(final Object value) {
final DynaProperty[] properties = getDynaProperties();
for (final DynaProperty property : properties) {
final String key = property.getName();
final Object prop = getDynaBean().get(key);
if (value == null) {
if (prop == null) {
return true;
}
} else if (value.equals(prop)) {
return true;
}
}
return false;
}
/**
* Converts the name of a property to the key type of this decorator.
*
* @param propertyName the name of a property
* @return the converted key to be used in the decorated map
*/
protected abstract K convertKey(String propertyName);
/**
* <p>
* Returns the Set of the property/value mappings in the decorated {@link DynaBean}.
* </p>
*
* <p>
* Each element in the Set is a {@code Map.Entry} type.
* </p>
*
* @return An unmodifiable set of the DynaBean property name/value pairs
*/
@Override
public Set<Map.Entry<K, Object>> entrySet() {
final DynaProperty[] properties = getDynaProperties();
final Set<Map.Entry<K, Object>> set = new HashSet<>(properties.length);
for (final DynaProperty property : properties) {
final K key = convertKey(property.getName());
final Object value = getDynaBean().get(property.getName());
set.add(new MapEntry<>(key, value));
}
return Collections.unmodifiableSet(set);
}
/**
* Gets 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.
*/
@Override
public Object get(final Object key) {
return getDynaBean().get(toString(key));
}
/**
* Provide access to the underlying {@link DynaBean} this Map decorates.
*
* @return the decorated {@link DynaBean}.
*/
public DynaBean getDynaBean() {
return dynaBean;
}
/**
* 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();
}
/**
* Indicate whether the decorated {@link DynaBean} has any properties.
*
* @return {@code true} if the {@link DynaBean} has no properties, otherwise {@code false}.
*/
@Override
public boolean isEmpty() {
return getDynaProperties().length == 0;
}
/**
* Indicate whether the Map is read only.
*
* @return {@code true} if the Map is read only, otherwise {@code false}.
*/
public boolean isReadOnly() {
return readOnly;
}
/**
* <p>
* Returns the Set of the property names in the decorated {@link DynaBean}.
* </p>
*
* <p>
* <strong>N.B.</strong>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.
*/
@Override
public Set<K> keySet() {
if (keySet != null) {
return keySet;
}
// Create a Set of the keys
final DynaProperty[] properties = getDynaProperties();
Set<K> set = new HashSet<>(properties.length);
for (final DynaProperty property : properties) {
set.add(convertKey(property.getName()));
}
set = Collections.unmodifiableSet(set);
// Cache the keySet if Not a MutableDynaClass
final DynaClass dynaClass = getDynaBean().getDynaClass();
if (!(dynaClass instanceof MutableDynaClass)) {
keySet = set;
}
return set;
}
/**
* Puts 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.
*/
@Override
public Object put(final K key, final Object value) {
if (isReadOnly()) {
throw new UnsupportedOperationException("Map is read only");
}
final String property = toString(key);
final 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.
*/
@Override
public void putAll(final Map<? extends K, ? extends Object> map) {
if (isReadOnly()) {
throw new UnsupportedOperationException("Map is read only");
}
map.forEach(this::put);
}
/**
* remove() operation is not supported.
*
* @param key The {@link DynaBean}'s property name
* @return the value removed
* @throws UnsupportedOperationException This operation is not yet supported
*/
@Override
public Object remove(final Object key) {
throw new UnsupportedOperationException();
}
/**
* Returns the number properties in the decorated {@link DynaBean}.
*
* @return The number of properties.
*/
@Override
public int size() {
return getDynaProperties().length;
}
/**
* Convenience method to convert an Object to a String.
*
* @param obj The Object to convert
* @return String representation of the object
*/
private String toString(final Object obj) {
return Objects.toString(obj, null);
}
/**
* Returns the set of property values in the decorated {@link DynaBean}.
*
* @return Unmodifiable collection of values.
*/
@Override
public Collection<Object> values() {
final DynaProperty[] properties = getDynaProperties();
final List<Object> values = new ArrayList<>(properties.length);
for (final DynaProperty property : properties) {
final String key = property.getName();
final Object value = getDynaBean().get(key);
values.add(value);
}
return Collections.unmodifiableList(values);
}
}