/*
    * $Id: BeanHelper.java 113 2004-10-22 19:22:56Z josem $
    *
    * Tarsis
    * Copyright (C) 2002 Talika Open Source Group
    *
    * This program is free software; you can redistribute it and/or modify
    * it under the terms of the GNU General Public License as published by
    * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   *
   */
  
  package org.talika.commons.util;
  
  import java.util.Map;
  import java.util.Iterator;
  import java.lang.reflect.Method;
  import java.lang.reflect.InvocationTargetException;
  
  /**
   * Utility class that allows access to beans setters and getters using reflexion.
   *
   * @author  Jose M. Palomar
   * @version $Revision: 113 $
   */
  public final class BeanHelper {
  
      // Constants
  
      // Fields
  
      /**
       * Class of bean we want access.
       */
      private Class beanClass;
  
      /**
       * Methods of bean we want access.
       */
      private Method[] beanMethods;
  
      // Constructors
      /**
       * Constructs a new <code>BeanHelper</code> for the specified class name.
       *
       * @param className String Name of class of bean we want access.
       * @throws ClassNotFoundException if the class cannot be located.
       */
      public BeanHelper(String className) throws ClassNotFoundException {
          this.beanClass = Class.forName(className);
          this.beanMethods = beanClass.getMethods();
      }
  
      // Methods
      /**
       * Creates a new instance of bean.
       *
       * @return Object new instance of bean.
       * @throws IllegalAccessException if the class or its nullary constructor is not
       * accessible.
       * @throws InstantiationException if this <code>Class</code> represents an
       * abstract class, an interface, an array class, a primitive type, or void; or
       * if the class has no nullary constructor; or if the instantiation fails for
       * some other reason.
       */
      public Object getInstance() throws IllegalAccessException, InstantiationException {
          return beanClass.newInstance();
      }
  
      /**
       * Call set method of one specified property of bean.
       *
       * @param instance Object instance of bean.
       * @param name String name of property.
       * @param value Object value of property.
       * @throws NoSuchMethodException if a matching method is not found.
       * @throws IllegalAccessException if the underlying method enforces Java language
       * access control and the underlying method is inaccessible.
       * @throws InvocationTargetException  if the underlying method throws an exception.
       */
      public void setProperty(Object instance, String name, Object value)
      throws NoSuchMethodException, IllegalAccessException, InvocationTargetException {
  
          String methodName = "set" + name.substring(0, 1).toUpperCase() +
                                      name.substring(1);
  
          Method method = findMethod(methodName);
          Object[] params = {value};
          method.invoke(instance, params);
 
     }
 
     /**
      * Call set method for a set of properties of bean.
      *
      * @param instance Object instance of bean.
      * @param props Map map of properties in which keys are properties names and
      * values are properties values.
      * @throws NoSuchMethodException if a matching method is not found.
      * @throws IllegalAccessException if the underlying method enforces Java language
      * access control and the underlying method is inaccessible.
      * @throws InvocationTargetException  if the underlying method throws an exception.
      */
     public void setProperties(Object instance, Map props)
     throws NoSuchMethodException, IllegalAccessException, InvocationTargetException {
 
         Iterator propNames = props.keySet().iterator();
         while (propNames.hasNext()) {
             String propName = (String) propNames.next();
             setProperty(instance, propName, props.get(propName));
         }
 
     }
 
     /**
      * Call get method for a property of bean.
      *
      * @param instance Object instance of bean.
      * @param name String name of property.
      * @return Object value of property.
      * @throws NoSuchMethodException if a matching method is not found.
      * @throws IllegalAccessException if the underlying method enforces Java language
      * access control and the underlying method is inaccessible.
      * @throws InvocationTargetException  if the underlying method throws an exception.
      */
     public Object getProperty(Object instance, String name)
     throws NoSuchMethodException, IllegalAccessException, InvocationTargetException {
 
         String methodName = "get" + name.substring(0, 1).toUpperCase() +
                                     name.substring(1);
 
         Method method = findMethod(methodName);
         return method.invoke(instance, null);
 
     }
 
     /**
      * Searchs for a method of bean.
      *
      * @param name String name of method.
      * @return Method method found.
      * @throws NoSuchMethodException if a matching method is not found.
      */
     private Method findMethod(String name) throws NoSuchMethodException {
 
         for (int i = 0; i < beanMethods.length; i++) {
             if (beanMethods[i].getName().equals(name) &&
                beanMethods[i].getParameterTypes().length == 1) {
                    return beanMethods[i];
             }
         }
 
         throw new NoSuchMethodException("Property method " + name + " not found");
 
     }
 
 }