beanmap.java

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/*
 * Copyright 1999-2004 The Apache Software Foundation
 *
 * Licensed 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.collections;

import java.beans.BeanInfo;
import java.beans.Introspector;
import java.beans.IntrospectionException;
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.Set;


/** An implementation of Map for JavaBeans which uses introspection to
  * get and put properties in the bean.
  *
  * If an exception occurs during attempts to get or set a property then the
  * property is considered non existent in the Map
  *
  * @since 1.0
  * @author <a href="mailto:[e-mail]">James Strachan</a>
  */

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.
     */
    public static HashMap defaultTransformers = new HashMap();
    
    static {
        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() );
                }
            }
        );
    }
    
    
    // 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
    //-------------------------------------------------------------------------

    /**
     *  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
     *  underyling 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>
     **/
    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
                ("Unable to copy bean values to cloned bean map: " +
                 exception);
        }

        return newMap;
    }

    /**
     *  Puts all of the writeable properties from the given BeanMap into this
     *  BeanMap.  Read-only properties will be ignored.
     *
     *  @param map  the BeanMap whose properties to put
     */
    public void putAllWriteable(BeanMap map) {
        Iterator readableKeys = map.readMethods.keySet().iterator();
        while(readableKeys.hasNext()) {
            Object key = readableKeys.next();
            if(getWriteMethod(key) != null) {
                this.put(key, map.get(key));
            }
        }
    }


    /**
     *  This method reinitializes the bean map to have default values for the
     *  bean's properties.  This is accomplished by constructing a new instance
     *  of the bean which the map uses as its underlying data source.  This
     *  behavior for <code>clear()</code> differs from the Map contract in that
     *  the mappings are not actually removed from the map (the mappings for a
     *  BeanMap are fixed).
     **/
    public void clear() {
        if(bean == null) return;

        Class beanClass = null;
        try {
            beanClass = bean.getClass();
            bean = beanClass.newInstance();
        }
        catch (Exception e) {
            throw new UnsupportedOperationException( "Could not create new instance of class: " + beanClass );
        }
    }

    /**
     *  Returns true if the bean defines a property with the given name.
     *  The given name must be a <Code>String</Code>; if not, this method
     *  returns false.  This method will also return false if the bean
     *  does not define a property with that name.
     *
     *  @param name  the name of the property to check
     *  @return false if the given name is null or is not a <Code>String</Code>;
     *    false if the bean does not define a property with that name; or
     *    true if the bean does define a property with that name
     */
    public boolean containsKey(Object name) {
        Method method = getReadMethod( name );
        return method != null;
    }

    /**
     *  Returns true if the bean defines a property whose current value is
     *  the given object.
     *
     *  @param value  the value to check
     *  @return false  true if the bean has at least one property whose 
     *    current value is that object, false otherwise
     */
    public boolean containsValue(Object value) {
        // use default implementation
        return super.containsValue( value );
    }

    /**
     *  Returns the value of the bean's property with the given name.
     *  The given name must be a {@link String} and must not be 
     *  null; otherwise, this method returns <Code>null</Code>.
     *  If the bean defines a property with the given name, the value of
     *  that property is returned.  Otherwise, <Code>null</Code> is 
     *  returned.
     *
     *  @param name  the name of the property whose value to return
     *  @return  the value of the property with that name
     */
    public Object get(Object name) {
        if ( bean != null ) {
            Method method = getReadMethod( name );
            if ( method != null ) {
                try {
                    return method.invoke( bean, NULL_ARGUMENTS );
                }
                catch (  IllegalAccessException e ) {
                    logWarn( e );
                }
                catch ( IllegalArgumentException e ) {
                    logWarn(  e );
                }
                catch ( InvocationTargetException e ) {
                    logWarn(  e );
                }
                catch ( NullPointerException e ) {
                    logWarn(  e );
                }
            }
        }
        return null;
    }

    /**
     *  Sets the bean property with the given name to the given value.
     *
     *  @param name  the name of the property to set
     *  @param value  the value to set that property to
     *  @return  the previous value of that property
     *  @throws IllegalArgumentException  if the given name is null;
     *    if the given name is not a {@link String}; if the bean doesn't
     *    define a property with that name; or if the bean property with
     *    that name is read-only
     */
    public Object put(Object name, Object value) throws IllegalArgumentException, ClassCastException {
        if ( bean != null ) {
            Object oldValue = get( name );
            Method method = getWriteMethod( name );
            if ( method == null ) {
                throw new IllegalArgumentException( "The bean of type: "+ bean.getClass().getName() + " has no property called: " + name );
            }
            try {
                Object[] arguments = createWriteMethodArguments( method, value );
                method.invoke( bean, arguments );

                Object newValue = get( name );
                firePropertyChange( name, oldValue, newValue );
            }
            catch ( InvocationTargetException e ) {
                logInfo( e );
                throw new IllegalArgumentException( e.getMessage() );
            }
            catch ( IllegalAccessException e ) {
                logInfo( e );
                throw new IllegalArgumentException( e.getMessage() );
            }
            return oldValue;
        }
        return null;
    }
                    
    /**
     *  Returns the number of properties defined by the bean.
     *
     *  @return  the number of properties defined by the bean
     */
    public int size() {
        return readMethods.size();
    }

    
    /**
     * Get the keys for this BeanMap.
     * 
     * @return BeanMap keys.  The Set returned by this method is not
     *         modifiable.
     */
    public Set keySet() {
        return Collections.unmodifiableSet(readMethods.keySet());
    }

    /**