org.apache.commons.beanutils.LazyDynaMap Maven / Gradle / Ivy
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* 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.Iterator;
/**
* Provides a light weight DynaBean facade to a Map
* with lazy map/list processing.
*
* Its a light weight DynaBean implementation because there is no
* actual DynaClass associated with this DynaBean - in fact
* it implements the DynaClass interface itself providing pseudo DynaClass
* behaviour from the actual values stored in the Map.
*
* As well providing rhe standard DynaBean access to the Map's properties
* this class also provides the usual Lazy behaviour:
*
* - Properties don't need to be pre-defined in a
DynaClass
* - Indexed properties (
Lists or Arrays) are automatically instantiated
* and grown so that they are large enough to cater for the index being set.
* - Mapped properties are automatically instantiated.
*
*
* Restricted DynaClass
* This class implements the MutableDynaClass interface.
* MutableDynaClass have a facility to restrict the DynaClass
* so that its properties cannot be modified. If the MutableDynaClass is
* restricted then calling any of the set() methods for a property which
* doesn't exist will result in a IllegalArgumentException being thrown.
*
* @author Niall Pemberton
*/
public class LazyDynaMap extends LazyDynaBean implements MutableDynaClass {
/**
* The name of this DynaClass (analogous to the
* getName() method of java.lang.Class).
*/
protected String name;
/**
* Controls whether changes to this DynaClass's properties are allowed.
*/
protected boolean restricted;
/**
* Controls whether the getDynaProperty() method returns
* null if a property doesn't exist - or creates a new one.
*
* Default is false.
*/
protected boolean returnNull = false;
// ------------------- Constructors ----------------------------------
/**
* Default Constructor.
*/
public LazyDynaMap() {
this(null, (Map)null);
}
/**
* Construct a new LazyDynaMap with the specified name.
*
* @param name Name of this DynaBean class
*/
public LazyDynaMap(String name) {
this(name, (Map)null);
}
/**
* Construct a new LazyDynaMap with the specified Map.
*
* @param values The Map backing this LazyDynaMap
*/
public LazyDynaMap(Map values) {
this(null, values);
}
/**
* Construct a new LazyDynaMap with the specified name and Map.
*
* @param name Name of this DynaBean class
* @param values The Map backing this LazyDynaMap
*/
public LazyDynaMap(String name, Map values) {
this.name = name == null ? "LazyDynaMap" : name;
this.values = values == null ? newMap() : values;
this.dynaClass = this;
}
/**
* Construct a new LazyDynaMap with the specified properties.
*
* @param properties Property descriptors for the supported properties
*/
public LazyDynaMap(DynaProperty[] properties) {
this(null, properties);
}
/**
* Construct a new LazyDynaMap with the specified name and properties.
*
* @param name Name of this DynaBean class
* @param properties Property descriptors for the supported properties
*/
public LazyDynaMap(String name, DynaProperty[] properties) {
this(name, (Map)null);
if (properties != null) {
for (int i = 0; i < properties.length; i++) {
add(properties[i]);
}
}
}
/**
* Construct a new LazyDynaMap based on an exisiting DynaClass
*
* @param dynaClass DynaClass to copy the name and properties from
*/
public LazyDynaMap(DynaClass dynaClass) {
this(dynaClass.getName(), dynaClass.getDynaProperties());
}
// ------------------- Public Methods ----------------------------------
/**
* Set the Map backing this DynaBean
*
* @param values The new Map of values
*/
public void setMap(Map values) {
this.values = values;
}
/**
* Return the underlying Map backing this DynaBean
* @return the underlying Map
* @since 1.8.0
*/
public Map getMap() {
return values;
}
// ------------------- DynaBean Methods ----------------------------------
/**
* Set the value of a simple property with the specified name.
*
* @param name Name of the property whose value is to be set
* @param value Value to which this property is to be set
*/
public void set(String name, Object value) {
if (isRestricted() && !values.containsKey(name)) {
throw new IllegalArgumentException
("Invalid property name '" + name + "' (DynaClass is restricted)");
}
values.put(name, value);
}
// ------------------- DynaClass Methods ----------------------------------
/**
* Return the name of this DynaClass (analogous to the
* getName() method of java.lang.ClassReturn a property descriptor for the specified property.
*
* If the property is not found and the returnNull indicator is
* true, this method always returns null.
*
* If the property is not found and the returnNull indicator is
* false a new property descriptor is created and returned (although
* its not actually added to the DynaClass's properties). This is the default
* beahviour.
*
* The reason for not returning a null property descriptor is that
* BeanUtils uses this method to check if a property exists
* before trying to set it - since these Map implementations automatically
* add any new properties when they are set, returning null from
* this method would defeat their purpose.
*
* @param name Name of the dynamic property for which a descriptor
* is requested
* @return The descriptor for the specified property
*
* @exception IllegalArgumentException if no property name is specified
*/
public DynaProperty getDynaProperty(String name) {
if (name == null) {
throw new IllegalArgumentException("Property name is missing.");
}
// If it doesn't exist and returnNull is false
// create a new DynaProperty
if (!values.containsKey(name) && isReturnNull()) {
return null;
}
Object value = values.get(name);
if (value == null) {
return new DynaProperty(name);
} else {
return new DynaProperty(name, value.getClass());
}
}
/**
* Return an array of ProperyDescriptors for the properties
* currently defined in this DynaClass. If no properties are defined, a
* zero-length array will be returned.
*
* FIXME - Should we really be implementing
* getBeanInfo() instead, which returns property descriptors
* and a bunch of other stuff?
* @return the set of properties for this DynaClass
*/
public DynaProperty[] getDynaProperties() {
int i = 0;
DynaProperty[] properties = new DynaProperty[values.size()];
Iterator iterator = values.keySet().iterator();
while (iterator.hasNext()) {
String name = (String)iterator.next();
Object value = values.get(name);
properties[i++] = new DynaProperty(name, value == null ? null : value.getClass());
}
return properties;
}
/**
* Instantiate and return a new DynaBean instance, associated
* with this DynaClass.
* @return A new DynaBean instance
*/
public DynaBean newInstance() {
// Create a new instance of the Map
Map newMap = null;
try {
newMap = (Map)getMap().getClass().newInstance();
} catch(Exception ex) {
newMap = newMap();
}
// Crate new LazyDynaMap and initialize properties
LazyDynaMap lazyMap = new LazyDynaMap(newMap);
DynaProperty[] properties = this.getDynaProperties();
if (properties != null) {
for (int i = 0; i < properties.length; i++) {
lazyMap.add(properties[i]);
}
}
return lazyMap;
}
// ------------------- MutableDynaClass Methods ----------------------------------
/**
* Is this DynaClass currently restricted.
* If restricted, no changes to the existing registration of
* property names, data types, readability, or writeability are allowed.
*
* @return true if this Mutable {@link DynaClass} is restricted,
* otherwise false
*/
public boolean isRestricted() {
return restricted;
}
/**
* Set whether this DynaClass is currently restricted.
* If restricted, no changes to the existing registration of
* property names, data types, readability, or writeability are allowed.
*
* @param restricted The new restricted state
*/
public void setRestricted(boolean restricted) {
this.restricted = restricted;
}
/**
* Add a new dynamic property with no restrictions on data type,
* readability, or writeability.
*
* @param name Name of the new dynamic property
*
* @exception IllegalArgumentException if name is null
*/
public void add(String name) {
add(name, null);
}
/**
* Add a new dynamic property with the specified data type, but with
* no restrictions on readability or writeability.
*
* @param name Name of the new dynamic property
* @param type Data type of the new dynamic property (null for no
* restrictions)
*
* @exception IllegalArgumentException if name is null
* @exception IllegalStateException if this DynaClass is currently
* restricted, so no new properties can be added
*/
public void add(String name, Class type) {
if (name == null) {
throw new IllegalArgumentException("Property name is missing.");
}
if (isRestricted()) {
throw new IllegalStateException("DynaClass is currently restricted. No new properties can be added.");
}
Object value = values.get(name);
// Check if the property already exists
if (value == null) {
values.put(name, type == null ? null : createProperty(name, type));
}
}
/**
* Add a new dynamic property with the specified data type, readability,
* and writeability.
*
* N.B.Support for readable/writeable properties has not been implemented
* and this method always throws a UnsupportedOperationException.
*
* I'm not sure the intention of the original authors for this method, but it seems to
* me that readable/writable should be attributes of the DynaProperty class
* (which they are not) and is the reason this method has not been implemented.
*
* @param name Name of the new dynamic property
* @param type Data type of the new dynamic property (null for no
* restrictions)
* @param readable Set to true if this property value
* should be readable
* @param writeable Set to true if this property value
* should be writeable
*
* @exception UnsupportedOperationException anytime this method is called
*/
public void add(String name, Class type, boolean readable, boolean writeable) {
throw new java.lang.UnsupportedOperationException("readable/writable properties not supported");
}
/**
* Add a new dynamic property.
*
* @param property Property the new dynamic property to add.
*
* @exception IllegalArgumentException if name is null
*/
protected void add(DynaProperty property) {
add(property.getName(), property.getType());
}
/**
* Remove the specified dynamic property, and any associated data type,
* readability, and writeability, from this dynamic class.
* NOTE - This does NOT cause any
* corresponding property values to be removed from DynaBean instances
* associated with this DynaClass.
*
* @param name Name of the dynamic property to remove
*
* @exception IllegalArgumentException if name is null
* @exception IllegalStateException if this DynaClass is currently
* restricted, so no properties can be removed
*/
public void remove(String name) {
if (name == null) {
throw new IllegalArgumentException("Property name is missing.");
}
if (isRestricted()) {
throw new IllegalStateException("DynaClass is currently restricted. No properties can be removed.");
}
// Remove, if property doesn't exist
if (values.containsKey(name)) {
values.remove(name);
}
}
// ------------------- Additional Public Methods ----------------------------------
/**
* Should this DynaClass return a null from
* the getDynaProperty(name) method if the property
* doesn't exist.
*
* @return true if a null {@link DynaProperty}
* should be returned if the property doesn't exist, otherwise
* false if a new {@link DynaProperty} should be created.
*/
public boolean isReturnNull() {
return returnNull;
}
/**
* Set whether this DynaClass should return a null from
* the getDynaProperty(name) method if the property
* doesn't exist.
*
* @param returnNull true if a null {@link DynaProperty}
* should be returned if the property doesn't exist, otherwise
* false if a new {@link DynaProperty} should be created.
*/
public void setReturnNull(boolean returnNull) {
this.returnNull = returnNull;
}
// ------------------- Protected Methods ----------------------------------
/**
* Indicate whether a property actually exists.
*
* N.B. Using getDynaProperty(name) == null
* doesn't work in this implementation because that method might
* return a DynaProperty if it doesn't exist (depending on the
* returnNull indicator).
*
* @param name Name of the dynamic property
* @return true if the property exists,
* otherwise false
* @exception IllegalArgumentException if no property name is specified
*/
protected boolean isDynaProperty(String name) {
if (name == null) {
throw new IllegalArgumentException("Property name is missing.");
}
return values.containsKey(name);
}
}