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BeanUtils provides an easy-to-use but flexible wrapper around reflection and introspection.
/*
* 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.io.Serializable;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.HashMap;
/**
* Minimal implementation of the DynaClass interface. Can be
* used as a convenience base class for more sophisticated implementations.
*
* IMPLEMENTATION NOTE - The DynaBean
* implementation class supplied to our constructor MUST have a one-argument
* constructor of its own that accepts a DynaClass. This is
* used to associate the DynaBean instance with this DynaClass.
*
* @author Craig McClanahan
* @version $Revision: 926529 $ $Date: 2010-03-23 07:44:24 -0400 (Tue, 23 Mar 2010) $
*/
public class BasicDynaClass implements DynaClass, Serializable {
// ----------------------------------------------------------- Constructors
/**
* Construct a new BasicDynaClass with default parameters.
*/
public BasicDynaClass() {
this(null, null, null);
}
/**
* Construct a new BasicDynaClass with the specified parameters.
*
* @param name Name of this DynaBean class
* @param dynaBeanClass The implementation class for new instances
*/
public BasicDynaClass(String name, Class dynaBeanClass) {
this(name, dynaBeanClass, null);
}
/**
* Construct a new BasicDynaClass with the specified parameters.
*
* @param name Name of this DynaBean class
* @param dynaBeanClass The implementation class for new intances
* @param properties Property descriptors for the supported properties
*/
public BasicDynaClass(String name, Class dynaBeanClass,
DynaProperty[] properties) {
super();
if (name != null) {
this.name = name;
}
if (dynaBeanClass == null) {
dynaBeanClass = BasicDynaBean.class;
}
setDynaBeanClass(dynaBeanClass);
if (properties != null) {
setProperties(properties);
}
}
// ----------------------------------------------------- Instance Variables
/**
* The constructor of the dynaBeanClass that we will use
* for creating new instances.
*/
protected transient Constructor constructor = null;
/**
* The method signature of the constructor we will use to create
* new DynaBean instances.
*/
protected static Class[] constructorTypes = { DynaClass.class };
/**
* The argument values to be passed to the constructore we will use
* to create new DynaBean instances.
*/
protected Object[] constructorValues = { this };
/**
* The DynaBean implementation class we will use for
* creating new instances.
*/
protected Class dynaBeanClass = BasicDynaBean.class;
/**
* The "name" of this DynaBean class.
*/
protected String name = this.getClass().getName();
/**
* The set of dynamic properties that are part of this DynaClass.
*/
protected DynaProperty[] properties = new DynaProperty[0];
/**
* The set of dynamic properties that are part of this DynaClass,
* keyed by the property name. Individual descriptor instances will
* be the same instances as those in the properties list.
*/
protected HashMap propertiesMap = new HashMap();
// ------------------------------------------------------ DynaClass Methods
/**
* Return the name of this DynaClass (analogous to the
* getName() method of java.lang.ClassDynaClass implementation class to support
* different dynamic classes, with different sets of properties.
*
* @return the name of the DynaClass
*/
public String getName() {
return (this.name);
}
/**
* Return a property descriptor for the specified property, if it exists;
* otherwise, return null.
*
* @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
("No property name specified");
}
return ((DynaProperty) propertiesMap.get(name));
}
/**
* 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() {
return (properties);
}
/**
* Instantiate and return a new DynaBean instance, associated
* with this DynaClass.
*
* @return A new DynaBean instance
* @exception IllegalAccessException if the Class or the appropriate
* constructor is not accessible
* @exception InstantiationException if this Class represents an abstract
* class, an array class, a primitive type, or void; or if instantiation
* fails for some other reason
*/
public DynaBean newInstance()
throws IllegalAccessException, InstantiationException {
try {
// Refind the constructor after a deserialization (if needed)
if (constructor == null) {
setDynaBeanClass(this.dynaBeanClass);
}
// Invoke the constructor to create a new bean instance
return ((DynaBean) constructor.newInstance(constructorValues));
} catch (InvocationTargetException e) {
throw new InstantiationException
(e.getTargetException().getMessage());
}
}
// --------------------------------------------------------- Public Methods
/**
* Return the Class object we will use to create new instances in the
* newInstance() method. This Class MUST
* implement the DynaBean interface.
*
* @return The class of the {@link DynaBean}
*/
public Class getDynaBeanClass() {
return (this.dynaBeanClass);
}
// ------------------------------------------------------ Protected Methods
/**
* Set the Class object we will use to create new instances in the
* newInstance() method. This Class MUST
* implement the DynaBean interface.
*
* @param dynaBeanClass The new Class object
*
* @exception IllegalArgumentException if the specified Class does not
* implement the DynaBean interface
*/
protected void setDynaBeanClass(Class dynaBeanClass) {
// Validate the argument type specified
if (dynaBeanClass.isInterface()) {
throw new IllegalArgumentException
("Class " + dynaBeanClass.getName() +
" is an interface, not a class");
}
if (!DynaBean.class.isAssignableFrom(dynaBeanClass)) {
throw new IllegalArgumentException
("Class " + dynaBeanClass.getName() +
" does not implement DynaBean");
}
// Identify the Constructor we will use in newInstance()
try {
this.constructor = dynaBeanClass.getConstructor(constructorTypes);
} catch (NoSuchMethodException e) {
throw new IllegalArgumentException
("Class " + dynaBeanClass.getName() +
" does not have an appropriate constructor");
}
this.dynaBeanClass = dynaBeanClass;
}
/**
* Set the list of dynamic properties supported by this DynaClass.
*
* @param properties List of dynamic properties to be supported
*/
protected void setProperties(DynaProperty[] properties) {
this.properties = properties;
propertiesMap.clear();
for (int i = 0; i < properties.length; i++) {
propertiesMap.put(properties[i].getName(), properties[i]);
}
}
}
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