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Commons Beanutils example source code file (LazyDynaMap.java)

This example Commons Beanutils source code file (LazyDynaMap.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

dynaclass, dynaproperty, dynaproperty, illegalargumentexception, illegalargumentexception, illegalstateexception, lazydynamap, lazydynamap, map, map, no, object, property, string, util

The Commons Beanutils LazyDynaMap.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.Iterator;

/**
 * <p>Provides a light weight DynaBean facade to a Map
 *  with <i>lazy map/list processing.

* * <p>Its a light weight DynaBean implementation because there is no * actual <code>DynaClass associated with this DynaBean - in fact * it implements the <code>DynaClass interface itself providing pseudo DynaClass * behaviour from the actual values stored in the <code>Map.

* * <p>As well providing rhe standard DynaBean access to the Map's properties * this class also provides the usual <i>Lazy behaviour:

* <ul> * <li>Properties don't need to be pre-defined in a DynaClass * <li>Indexed properties (Lists or Arrays) are automatically instantiated * and <i>grown so that they are large enough to cater for the index being set. * <li>Mapped properties are automatically instantiated. * </ul> * * <p>Restricted DynaClass

* <p>This class implements the MutableDynaClass interface. * <code>MutableDynaClass have a facility to restrict the DynaClass * so that its properties cannot be modified. If the <code>MutableDynaClass is * restricted then calling any of the <code>set() methods for a property which * doesn't exist will result in a <code>IllegalArgumentException being thrown.

* * @author Niall Pemberton */ public class LazyDynaMap extends LazyDynaBean implements MutableDynaClass { /** * The name of this DynaClass (analogous to the * <code>getName() method of java.lang.Class). */ protected String name; /** * Controls whether changes to this DynaClass's properties are allowed. */ protected boolean restricted; /** * <p>Controls whether the getDynaProperty() method returns * null if a property doesn't exist - or creates a new one.</p> * * <p>Default is false. */ protected boolean returnNull = false; // ------------------- Constructors ---------------------------------- /** * Default Constructor. */ public LazyDynaMap() { this(null, (Map)null); } /** * Construct a new <code>LazyDynaMap with the specified name. * * @param name Name of this DynaBean class */ public LazyDynaMap(String name) { this(name, (Map)null); } /** * Construct a new <code>LazyDynaMap with the specified Map. * * @param values The Map backing this <code>LazyDynaMap */ public LazyDynaMap(Map values) { this(null, values); } /** * Construct a new <code>LazyDynaMap with the specified name and Map. * * @param name Name of this DynaBean class * @param values The Map backing this <code>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 <code>LazyDynaMap with the specified properties. * * @param properties Property descriptors for the supported properties */ public LazyDynaMap(DynaProperty[] properties) { this(null, properties); } /** * Construct a new <code>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 <code>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 <code>DynaBean * * @param values The new Map of values */ public void setMap(Map values) { this.values = values; } /** * Return the underlying Map backing this <code>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 * <code>getName() method of java.lang.Class * * <p>If the property is not found and the returnNull indicator is * <code>true, this method always returns null.

* * <p>If the property is not found and the returnNull indicator is * <code>false a new property descriptor is created and returned (although * its not actually added to the DynaClass's properties). This is the default * beahviour.</p> * * <p>The reason for not returning a null property descriptor is that * <code>BeanUtils uses this method to check if a property exists * before trying to set it - since these <i>Map implementations automatically * add any new properties when they are set, returning <code>null from * this method would defeat their purpose.</p> * * @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()); } } /** * <p>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.</p> * * <p>FIXME - Should we really be implementing * <code>getBeanInfo() instead, which returns property descriptors * and a bunch of other stuff?</p> * @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 <code>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 ---------------------------------- /** * <p>Is this DynaClass currently restricted.

* <p>If restricted, no changes to the existing registration of * property names, data types, readability, or writeability are allowed.</p> * * @return <code>true if this Mutable {@link DynaClass} is restricted, * otherwise <code>false */ public boolean isRestricted() { return restricted; } /** * <p>Set whether this DynaClass is currently restricted.

* <p>If restricted, no changes to the existing registration of * property names, data types, readability, or writeability are allowed.</p> * * @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)); } } /** * <p>Add a new dynamic property with the specified data type, readability, * and writeability.</p> * * <p>N.B.Support for readable/writeable properties has not been implemented * and this method always throws a <code>UnsupportedOperationException.

* * <p>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 <code>DynaProperty class * (which they are not) and is the reason this method has not been implemented.</p> * * @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 <code>true if this property value * should be readable * @param writeable Set to <code>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. * <strong>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 <code>null from * the <code>getDynaProperty(name) method if the property * doesn't exist. * * @return <code>true if a null {@link DynaProperty} * should be returned if the property doesn't exist, otherwise * <code>false if a new {@link DynaProperty} should be created. */ public boolean isReturnNull() { return returnNull; } /** * Set whether this DynaClass should return a <code>null from * the <code>getDynaProperty(name) method if the property * doesn't exist. * * @param returnNull <code>true if a null {@link DynaProperty} * should be returned if the property doesn't exist, otherwise * <code>false if a new {@link DynaProperty} should be created. */ public void setReturnNull(boolean returnNull) { this.returnNull = returnNull; } // ------------------- Protected Methods ---------------------------------- /** * <p>Indicate whether a property actually exists.

* * <p>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 * <code>returnNull indicator).

* * @param name Name of the dynamic property * @return <code>true if the property exists, * otherwise <code>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); } }

Other Commons Beanutils examples (source code examples)

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