beanmap.java

这是一个有关common beanutils 的源码

/*
 * 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.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.AbstractMap;
import java.util.AbstractSet;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import org.apache.commons.collections.list.UnmodifiableList;
import org.apache.commons.collections.keyvalue.AbstractMapEntry;
import org.apache.commons.collections.set.UnmodifiableSet;
import org.apache.commons.collections.Transformer;

/** 
 * An implementation of Map for JavaBeans which uses introspection to
 * get and put properties in the bean.
 * <p>
 * If an exception occurs during attempts to get or set a property then the
 * property is considered non existent in the Map
 *
 * @version $Revision: 557796 $ $Date: 2007-07-19 23:28:49 +0100 (Thu, 19 Jul 2007) $
 * 
 * @author James Strachan
 * @author Stephen Colebourne
 */
public class BeanMap extends AbstractMap implements Cloneable {

    private transient Object bean;

    private transient HashMap readMethods = new HashMap();
    private transient HashMap writeMethods = new HashMap();
    private transient HashMap types = new HashMap();

    /**
     * An empty array.  Used to invoke accessors via reflection.
     */
    public static final Object[] NULL_ARGUMENTS = {};

    /**
     * Maps primitive Class types to transformers.  The transformer
     * transform strings into the appropriate primitive wrapper.
     *
     * N.B. private & unmodifiable replacement for the (public & static) defaultTransformers instance.
     */
    private static Map typeTransformers = Collections.unmodifiableMap(createTypeTransformers());

    /**
     * This HashMap has been made unmodifiable to prevent issues when
     * loaded in a shared ClassLoader enviroment.
     *
     * @see http://issues.apache.org/jira/browse/BEANUTILS-112
     * @deprecated Use {@link BeanMap#getTypeTransformer(Class)} method
     */
    public static HashMap defaultTransformers = new HashMap() {
        public void clear() {
            throw new UnsupportedOperationException();
        }
        public boolean containsKey(Object key) {
            return typeTransformers.containsKey(key);
        }
        public boolean containsValue(Object value) {
            return typeTransformers.containsValue(value);
        }
        public Set entrySet() {
            return typeTransformers.entrySet();
        }
        public Object get(Object key) {
            return typeTransformers.get(key);
        }
        public boolean isEmpty() {
            return false;
        }
        public Set keySet() {
            return typeTransformers.keySet();
        }
        public Object put(Object key, Object value) {
            throw new UnsupportedOperationException();
        }
        public void putAll(Map m) {
            throw new UnsupportedOperationException();
        }
        public Object remove(Object key) {
            throw new UnsupportedOperationException();
        }
        public int size() {
            return typeTransformers.size();
        }
        public Collection values() {
            return typeTransformers.values();
        }
    };
    
    private static Map createTypeTransformers() {
        Map defaultTransformers = new HashMap();
        defaultTransformers.put( 
            Boolean.TYPE, 
            new Transformer() {
                public Object transform( Object input ) {
                    return Boolean.valueOf( input.toString() );
                }
            }
        );
        defaultTransformers.put( 
            Character.TYPE, 
            new Transformer() {
                public Object transform( Object input ) {
                    return new Character( input.toString().charAt( 0 ) );
                }
            }
        );
        defaultTransformers.put( 
            Byte.TYPE, 
            new Transformer() {
                public Object transform( Object input ) {
                    return Byte.valueOf( input.toString() );
                }
            }
        );
        defaultTransformers.put( 
            Short.TYPE, 
            new Transformer() {
                public Object transform( Object input ) {
                    return Short.valueOf( input.toString() );
                }
            }
        );
        defaultTransformers.put( 
            Integer.TYPE, 
            new Transformer() {
                public Object transform( Object input ) {
                    return Integer.valueOf( input.toString() );
                }
            }
        );
        defaultTransformers.put( 
            Long.TYPE, 
            new Transformer() {
                public Object transform( Object input ) {
                    return Long.valueOf( input.toString() );
                }
            }
        );
        defaultTransformers.put( 
            Float.TYPE, 
            new Transformer() {
                public Object transform( Object input ) {
                    return Float.valueOf( input.toString() );
                }
            }
        );
        defaultTransformers.put( 
            Double.TYPE, 
            new Transformer() {
                public Object transform( Object input ) {
                    return Double.valueOf( input.toString() );
                }
            }
        );
        return defaultTransformers;
    }
    
    
    // Constructors
    //-------------------------------------------------------------------------

    /**
     * Constructs a new empty <code>BeanMap</code>.
     */
    public BeanMap() {
    }

    /**
     * Constructs a new <code>BeanMap</code> that operates on the 
     * specified bean.  If the given bean is <code>null</code>, then
     * this map will be empty.
     *
     * @param bean  the bean for this map to operate on
     */
    public BeanMap(Object bean) {
        this.bean = bean;
        initialise();
    }

    // Map interface
    //-------------------------------------------------------------------------

    /**
     * Renders a string representation of this object.
     * @return a <code>String</code> representation of this object
     */
    public String toString() {
        return "BeanMap<" + String.valueOf(bean) + ">";
    }
    
    /**
     * Clone this bean map using the following process: 
     *
     * <ul>
     * <li>If there is no underlying bean, return a cloned BeanMap without a
     * bean.
     *
     * <li>Since there is an underlying bean, try to instantiate a new bean of
     * the same type using Class.newInstance().
     * 
     * <li>If the instantiation fails, throw a CloneNotSupportedException
     *
     * <li>Clone the bean map and set the newly instantiated bean as the
     * underlying bean for the bean map.
     *
     * <li>Copy each property that is both readable and writable from the
     * existing object to a cloned bean map.  
     *
     * <li>If anything fails along the way, throw a
     * CloneNotSupportedException.
     *
     * <ul>
     *
     * @return a cloned instance of this bean map
     * @throws CloneNotSupportedException if the underlying bean
     * cannot be cloned
     */
    public Object clone() throws CloneNotSupportedException {
        BeanMap newMap = (BeanMap)super.clone();

        if(bean == null) {
            // no bean, just an empty bean map at the moment.  return a newly
            // cloned and empty bean map.
            return newMap;
        }

        Object newBean = null;            
        Class beanClass = null;
        try {
            beanClass = bean.getClass();
            newBean = beanClass.newInstance();
        } catch (Exception e) {
            // unable to instantiate
            throw new CloneNotSupportedException
                ("Unable to instantiate the underlying bean \"" +
                 beanClass.getName() + "\": " + e);
        }
            
        try {
            newMap.setBean(newBean);
        } catch (Exception exception) {
            throw new CloneNotSupportedException
                ("Unable to set bean in the cloned bean map: " + 
                 exception);
        }
            
        try {
            // copy only properties that are readable and writable.  If its
            // not readable, we can't get the value from the old map.  If
            // its not writable, we can't write a value into the new map.
            Iterator readableKeys = readMethods.keySet().iterator();
            while(readableKeys.hasNext()) {
                Object key = readableKeys.next();
                if(getWriteMethod(key) != null) {
                    newMap.put(key, get(key));
                }
            }
        } catch (Exception exception) {
            throw new CloneNotSupportedException