2009/05/20 - Apache Shale has been retired.

 /*

  * 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.shale.util;

 import java.beans.BeanInfo;

 import java.beans.IntrospectionException;

 import java.beans.Introspector;

 import java.beans.PropertyDescriptor;

 import java.lang.reflect.InvocationTargetException;

 import java.lang.reflect.Method;

 import javax.faces.el.EvaluationException;

 import javax.faces.el.PropertyNotFoundException;

 /**

  * <p>Helper class to provide access to the properties of JavaBeans.  This

  * implementation is stateless and maintains no cached information, so

  * instances may be freely created and destroyed, with no side effects

  * (unless there are side effects from caching inside the JDK itself).</p>

  *

  * $Id: PropertyHelper.java 464373 2006-10-16 04:21:54Z rahul $

  *

  * @since 1.0.1

  */

 public class PropertyHelper {

     // ---------------------------------------------------------- Public Methods

     /**

      * <p>Return the value of the specified property from the specified bean.</p>

      *

      * @param bean Bean whose property is to be retrieved

      * @param name Name of the property to get

      *

      * @exception PropertyNotFoundException if the bean class does not have

      *  a property with the specified name, or if the property is write only

      * @exception EvaluationException if an exception occurs while

      *  retrieving the property value

      */

     public Object getValue(Object bean, String name) {

         PropertyDescriptor descriptor = descriptor(bean, name);

         Method method = descriptor.getReadMethod();

         if (method == null) {

             throw new PropertyNotFoundException(name);

         }

         try {

             return method.invoke(bean, new Object[0]);

         } catch (InvocationTargetException e) {

             throw new EvaluationException(e.getCause());

         } catch (Exception e) {

             throw new EvaluationException(e);

         }

     }

     /**

      * <p>Return <code>true</code> if the specified property is read only on

      * the underlying bean class.</p>

      *

      * @param bean Bean whose property is to be checked

      * @param name Name of the property to check

      *

      * @exception PropertyNotFoundException if the bean class does not have

      *  a property with the specified name, or if the property is write only

      * @exception EvaluationException if an exception occurs while

      *  checking the read only status

      */

     public boolean isReadOnly(Object bean, String name) {

         PropertyDescriptor descriptor = descriptor(bean, name);

         if (descriptor.getReadMethod() != null) {

             return descriptor.getWriteMethod() == null;

         }

         throw new PropertyNotFoundException(name);

     }

     /**

      * <p>Return the type of the specified property on the underlying bean

      * class.</p>

      *

      * @param bean Bean whose property is to be analyzed

      * @param name Name of the property to return the type of

      *

      * @exception PropertyNotFoundException if the bean class does not have

      *  a property with the specified name

      * @exception EvaluationException if an exception occurs while

      *  retrieving the property type

      */

     public Class getType(Object bean, String name) {

         PropertyDescriptor descriptor = descriptor(bean, name);

         return descriptor.getPropertyType();

     }

     /**

      * <p>Set the specified value on the specified property of the specified

      * bean.</p>

      *

      * @param bean Bean whose property is to be set

      * @param name Name of the property to be set

      * @param value New value for this property

      *

      * @exception PropertyNotFoundException if the bean class does not have

      *  a property with the specified name, or if the property is read only

      * @exception EvaluationException if an exception occurs while

      *  setting the property value

      */

     public void setValue(Object bean, String name, Object value) {

         PropertyDescriptor descriptor = descriptor(bean, name);

         Method method = descriptor.getWriteMethod();

         if (method == null) {

             throw new PropertyNotFoundException(name);

         }

         try {

             method.invoke(bean, new Object[] { value });

         } catch (InvocationTargetException e) {

             throw new EvaluationException(e.getCause());

         } catch (Exception e) {

             throw new EvaluationException(e);

         }

     }

     // ------------------------------------------------------- Private Methods

     /**

      * <p>Return the <code>PropertyDescriptor</code> for the specified

      * property of the specified class.</p>

      *

      * @param bean Bean whose property descriptor is to be returned

      * @param name Name of the property to retrieve a descrpitor for

      *

      * @exception PropertyNotFoundException if the bean class does not have

      *  a property with the specified name

      * @exception EvaluationException if an exception occurs introspecting

      *  the underlying bean class

      */

     private PropertyDescriptor descriptor(Object bean, String name) {

         BeanInfo beanInfo = null;

         try {

             beanInfo = Introspector.getBeanInfo(bean.getClass());

         } catch (IntrospectionException e) {

             throw new EvaluationException(e);

         }

         PropertyDescriptor descriptors[] = beanInfo.getPropertyDescriptors();

         if (descriptors == null) {

             descriptors = new PropertyDescriptor[0];

         }

         for (int i = 0; i < descriptors.length; i++) {

             if (name.equals(descriptors[i].getName())) {

                 return descriptors[i];

             }

         }

         throw new PropertyNotFoundException(name);

     }

 }