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Commons Beanutils example source code file (LazyDynaClass.java)

This example Commons Beanutils source code file (LazyDynaClass.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

basicdynaclass, class, class, dynaclass, dynaproperty, dynaproperty, illegalargumentexception, illegalargumentexception, illegalstateexception, lazydynaclass, lazydynaclass, mutabledynaclass, no, property

The Commons Beanutils LazyDynaClass.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;

/**
 * <p>DynaClass which implements the MutableDynaClass interface.

* * <p>A MutableDynaClass is a specialized extension to DynaClass * that allows properties to be added or removed dynamically.</p> * * <p>This implementation has one slightly unusual default behaviour - calling * the <code>getDynaProperty(name) method for a property which doesn't * exist returns a <code>DynaProperty rather than null. The * reason for this is that <code>BeanUtils calls this method to check if * a property exists before trying to set the value. This would defeat the object * of the <code>LazyDynaBean which automatically adds missing properties * when any of its <code>set() methods are called. For this reason the * <code>isDynaProperty(name) method has been added to this implementation * in order to determine if a property actually exists. If the more <i>normal * behaviour of returning <code>null is required, then this can be achieved * by calling the <code>setReturnNull(true).

* * <p>The add(name, type, readable, writable) method is not implemented * and always throws an <code>UnsupportedOperationException. I believe * this attributes need to be added to the <code>DynaProperty class * in order to control read/write facilities.</p> * * @see LazyDynaBean * @author Niall Pemberton */ public class LazyDynaClass extends BasicDynaClass implements MutableDynaClass { /** * 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; /** * Construct a new LazyDynaClass with default parameters. */ public LazyDynaClass() { this(null, (DynaProperty[])null); } /** * Construct a new LazyDynaClass with the specified name. * * @param name Name of this DynaBean class */ public LazyDynaClass(String name) { this(name, (DynaProperty[])null); } /** * Construct a new LazyDynaClass with the specified name and DynaBean class. * * @param name Name of this DynaBean class * @param dynaBeanClass The implementation class for new instances */ public LazyDynaClass(String name, Class dynaBeanClass) { this(name, dynaBeanClass, null); } /** * Construct a new LazyDynaClass with the specified name and properties. * * @param name Name of this DynaBean class * @param properties Property descriptors for the supported properties */ public LazyDynaClass(String name, DynaProperty[] properties) { this(name, LazyDynaBean.class, properties); } /** * Construct a new LazyDynaClass with the specified name, DynaBean class and properties. * * @param name Name of this DynaBean class * @param dynaBeanClass The implementation class for new intances * @param properties Property descriptors for the supported properties */ public LazyDynaClass(String name, Class dynaBeanClass, DynaProperty properties[]) { super(name, dynaBeanClass, properties); } /** * <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 {@link MutableDynaClass} cannot be changed * 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 <code>true if this {@link MutableDynaClass} cannot * be changed otherwise <code>false */ public void setRestricted(boolean restricted) { this.restricted = restricted; } /** * 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; } /** * 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 * @exception IllegalStateException if this DynaClass is currently * restricted, so no new properties can be added */ public void add(String name) { add(new DynaProperty(name)); } /** * 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 (type == null) { add(name); } else { add(new DynaProperty(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 * @exception IllegalStateException if this DynaClass is currently * restricted, so no new properties can be added */ protected void add(DynaProperty property) { if (property.getName() == null) { throw new IllegalArgumentException("Property name is missing."); } if (isRestricted()) { throw new IllegalStateException("DynaClass is currently restricted. No new properties can be added."); } // Check if property already exists if (propertiesMap.get(property.getName()) != null) { return; } // Create a new property array with the specified property DynaProperty[] oldProperties = getDynaProperties(); DynaProperty[] newProperties = new DynaProperty[oldProperties.length+1]; System.arraycopy(oldProperties, 0, newProperties, 0, oldProperties.length); newProperties[oldProperties.length] = property; // Update the properties setProperties(newProperties); } /** * 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."); } // Ignore if property doesn't exist if (propertiesMap.get(name) == null) { return; } // Create a new property array of without the specified property DynaProperty[] oldProperties = getDynaProperties(); DynaProperty[] newProperties = new DynaProperty[oldProperties.length-1]; int j = 0; for (int i = 0; i < oldProperties.length; i++) { if (!(name.equals(oldProperties[i].getName()))) { newProperties[j] = oldProperties[i]; j++; } } // Update the properties setProperties(newProperties); } /** * <p>Return a property descriptor for the specified property.

* * <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>Lazy 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 dyna property for the specified name * * @exception IllegalArgumentException if no property name is specified */ public DynaProperty getDynaProperty(String name) { if (name == null) { throw new IllegalArgumentException("Property name is missing."); } DynaProperty dynaProperty = (DynaProperty)propertiesMap.get(name); // If it doesn't exist and returnNull is false // create a new DynaProperty if (dynaProperty == null && !isReturnNull() && !isRestricted()) { dynaProperty = new DynaProperty(name); } return dynaProperty; } /** * <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 The name of the property to check * @return <code>true if there is a property of the * specified name, otherwise <code>false * @exception IllegalArgumentException if no property name is specified */ public boolean isDynaProperty(String name) { if (name == null) { throw new IllegalArgumentException("Property name is missing."); } return propertiesMap.get(name) == null ? false : true; } }

Other Commons Beanutils examples (source code examples)

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