beanutilsbean.java

APACHE 公司出的java bean 工具包

/*
 * 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.beans.IndexedPropertyDescriptor;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Array;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import org.apache.commons.beanutils.expression.Resolver;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;


/**
 * <p>JavaBean property population methods.</p>
 *
 * <p>This class provides implementations for the utility methods in
 * {@link BeanUtils}.
 * Different instances can be used to isolate caches between classloaders
 * and to vary the value converters registered.</p>
 *
 * @author Craig R. McClanahan
 * @author Ralph Schaer
 * @author Chris Audley
 * @author Rey Francois
 * @author Gregor Rayman
 * @version $Revision: 556229 $ $Date: 2007-07-14 07:11:19 +0100 (Sat, 14 Jul 2007) $
 * @see BeanUtils
 * @since 1.7
 */

public class BeanUtilsBean {


    // ------------------------------------------------------ Private Class Variables

    /** 
     * Contains <code>BeanUtilsBean</code> instances indexed by context classloader.
     */
    private static final ContextClassLoaderLocal 
            BEANS_BY_CLASSLOADER = new ContextClassLoaderLocal() {
                        // Creates the default instance used when the context classloader is unavailable
                        protected Object initialValue() {
                            return new BeanUtilsBean();
                        }
                    };
    
    /** 
     * Gets the instance which provides the functionality for {@link BeanUtils}.
     * This is a pseudo-singleton - an single instance is provided per (thread) context classloader.
     * This mechanism provides isolation for web apps deployed in the same container.
     *
     * @return The (pseudo-singleton) BeanUtils bean instance
     */
    public static BeanUtilsBean getInstance() {
        return (BeanUtilsBean) BEANS_BY_CLASSLOADER.get();
    }

    /** 
     * Sets the instance which provides the functionality for {@link BeanUtils}.
     * This is a pseudo-singleton - an single instance is provided per (thread) context classloader.
     * This mechanism provides isolation for web apps deployed in the same container.
     * 
     * @param newInstance The (pseudo-singleton) BeanUtils bean instance
     */
    public static void setInstance(BeanUtilsBean newInstance) {
        BEANS_BY_CLASSLOADER.set(newInstance);
    }

    // --------------------------------------------------------- Attributes

    /**
     * Logging for this instance
     */
    private Log log = LogFactory.getLog(BeanUtils.class);
    
    /** Used to perform conversions between object types when setting properties */
    private ConvertUtilsBean convertUtilsBean;
    
    /** Used to access properties*/
    private PropertyUtilsBean propertyUtilsBean;

    /** A reference to Throwable's initCause method, or null if it's not there in this JVM */
    private static final Method INIT_CAUSE_METHOD = getInitCauseMethod();

    // --------------------------------------------------------- Constuctors

    /** 
     * <p>Constructs an instance using new property 
     * and conversion instances.</p>
     */
    public BeanUtilsBean() {
        this(new ConvertUtilsBean(), new PropertyUtilsBean());
    }

    /** 
     * <p>Constructs an instance using given conversion instances
     * and new {@link PropertyUtilsBean} instance.</p>
     *
     * @param convertUtilsBean use this <code>ConvertUtilsBean</code> 
     * to perform conversions from one object to another
     *
     * @since 1.8.0
     */
    public BeanUtilsBean(ConvertUtilsBean convertUtilsBean) {
        this(convertUtilsBean, new PropertyUtilsBean());
    }

    /** 
     * <p>Constructs an instance using given property and conversion instances.</p>
     *
     * @param convertUtilsBean use this <code>ConvertUtilsBean</code> 
     * to perform conversions from one object to another
     * @param propertyUtilsBean use this <code>PropertyUtilsBean</code>
     * to access properties
     */
    public BeanUtilsBean(
                            ConvertUtilsBean convertUtilsBean, 
                            PropertyUtilsBean propertyUtilsBean) {
                            
        this.convertUtilsBean = convertUtilsBean;
        this.propertyUtilsBean = propertyUtilsBean;
    }

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

    /**
     * <p>Clone a bean based on the available property getters and setters,
     * even if the bean class itself does not implement Cloneable.</p>
     *
     * <p>
     * <strong>Note:</strong> this method creates a <strong>shallow</strong> clone.
     * In other words, any objects referred to by the bean are shared with the clone
     * rather than being cloned in turn.
     * </p>
     *
     * @param bean Bean to be cloned
     * @return the cloned bean
     *
     * @exception IllegalAccessException if the caller does not have
     *  access to the property accessor method
     * @exception InstantiationException if a new instance of the bean's
     *  class cannot be instantiated
     * @exception InvocationTargetException if the property accessor method
     *  throws an exception
     * @exception NoSuchMethodException if an accessor method for this
     *  property cannot be found
     */
    public Object cloneBean(Object bean)
            throws IllegalAccessException, InstantiationException,
            InvocationTargetException, NoSuchMethodException {

        if (log.isDebugEnabled()) {
            log.debug("Cloning bean: " + bean.getClass().getName());
        }
        Object newBean = null;
        if (bean instanceof DynaBean) {
            newBean = ((DynaBean) bean).getDynaClass().newInstance();
        } else {
            newBean = bean.getClass().newInstance();
        }
        getPropertyUtils().copyProperties(newBean, bean);
        return (newBean);

    }


    /**
     * <p>Copy property values from the origin bean to the destination bean
     * for all cases where the property names are the same.  For each
     * property, a conversion is attempted as necessary.  All combinations of
     * standard JavaBeans and DynaBeans as origin and destination are
     * supported.  Properties that exist in the origin bean, but do not exist
     * in the destination bean (or are read-only in the destination bean) are
     * silently ignored.</p>
     *
     * <p>If the origin "bean" is actually a <code>Map</code>, it is assumed
     * to contain String-valued <strong>simple</strong> property names as the keys, pointing at
     * the corresponding property values that will be converted (if necessary)
     * and set in the destination bean. <strong>Note</strong> that this method
     * is intended to perform a "shallow copy" of the properties and so complex
     * properties (for example, nested ones) will not be copied.</p>
     *
     * <p>This method differs from <code>populate()</code>, which
     * was primarily designed for populating JavaBeans from the map of request
     * parameters retrieved on an HTTP request, is that no scalar->indexed
     * or indexed->scalar manipulations are performed.  If the origin property
     * is indexed, the destination property must be also.</p>
     *
     * <p>If you know that no type conversions are required, the
     * <code>copyProperties()</code> method in {@link PropertyUtils} will
     * execute faster than this method.</p>
     *
     * <p><strong>FIXME</strong> - Indexed and mapped properties that do not
     * have getter and setter methods for the underlying array or Map are not
     * copied by this method.</p>
     *
     * @param dest Destination bean whose properties are modified
     * @param orig Origin bean whose properties are retrieved
     *
     * @exception IllegalAccessException if the caller does not have
     *  access to the property accessor method
     * @exception IllegalArgumentException if the <code>dest</code> or
     *  <code>orig</code> argument is null or if the <code>dest</code> 
     *  property type is different from the source type and the relevant
     *  converter has not been registered.
     * @exception InvocationTargetException if the property accessor method
     *  throws an exception
     */
    public void copyProperties(Object dest, Object orig)
        throws IllegalAccessException, InvocationTargetException {

        // Validate existence of the specified beans
        if (dest == null) {
            throw new IllegalArgumentException
                    ("No destination bean specified");
        }
        if (orig == null) {
            throw new IllegalArgumentException("No origin bean specified");
        }
        if (log.isDebugEnabled()) {
            log.debug("BeanUtils.copyProperties(" + dest + ", " +
                      orig + ")");
        }

        // Copy the properties, converting as necessary
        if (orig instanceof DynaBean) {
            DynaProperty[] origDescriptors =
                ((DynaBean) orig).getDynaClass().getDynaProperties();
            for (int i = 0; i < origDescriptors.length; i++) {
                String name = origDescriptors[i].getName();
                // Need to check isReadable() for WrapDynaBean
                // (see Jira issue# BEANUTILS-61)
                if (getPropertyUtils().isReadable(orig, name) &&
                    getPropertyUtils().isWriteable(dest, name)) {
                    Object value = ((DynaBean) orig).get(name);
                    copyProperty(dest, name, value);
                }
            }
        } else if (orig instanceof Map) {
            Iterator names = ((Map) orig).keySet().iterator();
            while (names.hasNext()) {
                String name = (String) names.next();
                if (getPropertyUtils().isWriteable(dest, name)) {
                    Object value = ((Map) orig).get(name);
                    copyProperty(dest, name, value);
                }
            }
        } else /* if (orig is a standard JavaBean) */ {
            PropertyDescriptor[] origDescriptors =
                getPropertyUtils().getPropertyDescriptors(orig);
            for (int i = 0; i < origDescriptors.length; i++) {
                String name = origDescriptors[i].getName();
                if ("class".equals(name)) {
                    continue; // No point in trying to set an object's class