lazydynabean.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.util.List;
import java.util.ArrayList;
import java.util.Map;
import java.util.HashMap;
import java.util.Date;
import java.lang.reflect.Array;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.io.Serializable;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * <p>DynaBean which automatically adds properties to the <code>DynaClass</code>
 *   and provides <i>Lazy List</i> and <i>Lazy Map</i> features.</p>
 *
 * <p>DynaBeans deal with three types of properties - <i>simple</i>, <i>indexed</i> and <i>mapped</i> and
 *    have the following <code>get()</code> and <code>set()</code> methods for
 *    each of these types:</p>
 *    <ul>
 *        <li><i>Simple</i> property methods - <code>get(name)</code> and
 *                          <code>set(name, value)</code></li>
 *        <li><i>Indexed</i> property methods - <code>get(name, index)</code> and
 *                          <code>set(name, index, value)</code></li>
 *        <li><i>Mapped</i> property methods - <code>get(name, key)</code> and
 *                          <code>set(name, key, value)</code></li>
 *    </ul>
 *
 * <p><b><u>Getting Property Values</u></b></p>
 * <p>Calling any of the <code>get()</code> methods, for a property which
 *    doesn't exist, returns <code>null</code> in this implementation.</p>
 *
 * <p><b><u>Setting Simple Properties</u></b></p>
 *    <p>The <code>LazyDynaBean</code> will automatically add a property to the <code>DynaClass</code>
 *       if it doesn't exist when the <code>set(name, value)</code> method is called.</p>
 *
 *     <code>DynaBean myBean = new LazyDynaBean();</code></br>
 *     <code>myBean.set("myProperty", "myValue");</code></br>
 *
 * <p><b><u>Setting Indexed Properties</u></b></p>
 *    <p>If the property <b>doesn't</b> exist, the <code>LazyDynaBean</code> will automatically add
 *       a property with an <code>ArrayList</code> type to the <code>DynaClass</code> when
 *       the <code>set(name, index, value)</code> method is called.
 *       It will also instantiate a new <code>ArrayList</code> and automatically <i>grow</i>
 *       the <code>List</code> so that it is big enough to accomodate the index being set.
 *       <code>ArrayList</code> is the default indexed property that LazyDynaBean uses but
 *       this can be easily changed by overriding the <code>defaultIndexedProperty(name)</code>
 *       method.</p>
 *
 *     <code>DynaBean myBean = new LazyDynaBean();</code></br>
 *     <code>myBean.set("myIndexedProperty", 0, "myValue1");</code></br>
 *     <code>myBean.set("myIndexedProperty", 1, "myValue2");</code></br>
 *
 *    <p>If the indexed property <b>does</b> exist in the <code>DynaClass</code> but is set to
 *      <code>null</code> in the <code>LazyDynaBean</code>, then it will instantiate a
 *      new <code>List</code> or <code>Array</code> as specified by the property's type
 *      in the <code>DynaClass</code> and automatically <i>grow</i> the <code>List</code>
 *      or <code>Array</code> so that it is big enough to accomodate the index being set.</p>
 *
 *     <code>DynaBean myBean = new LazyDynaBean();</code></br>
 *     <code>MutableDynaClass myClass = (MutableDynaClass)myBean.getDynaClass();</code></br>
 *     <code>myClass.add("myIndexedProperty", int[].class);</code></br>
 *     <code>myBean.set("myIndexedProperty", 0, new Integer(10));</code></br>
 *     <code>myBean.set("myIndexedProperty", 1, new Integer(20));</code></br>
 *
 * <p><b><u>Setting Mapped Properties</u></b></p>
 *    <p>If the property <b>doesn't</b> exist, the <code>LazyDynaBean</code> will automatically add
 *       a property with a <code>HashMap</code> type to the <code>DynaClass</code> and
 *       instantiate a new <code>HashMap</code> in the DynaBean when the
 *       <code>set(name, key, value)</code> method is called. <code>HashMap</code> is the default
 *       mapped property that LazyDynaBean uses but this can be easily changed by overriding
 *       the <code>defaultMappedProperty(name)</code> method.</p>
 *
 *     <code>DynaBean myBean = new LazyDynaBean();</code></br>
 *     <code>myBean.set("myMappedProperty", "myKey", "myValue");</code></br>
 *
 *    <p>If the mapped property <b>does</b> exist in the <code>DynaClass</code> but is set to
 *      <code>null</code> in the <code>LazyDynaBean</code>, then it will instantiate a
 *      new <code>Map</code> as specified by the property's type in the <code>DynaClass</code>.</p>
 *
 *     <code>DynaBean myBean = new LazyDynaBean();</code></br>
 *     <code>MutableDynaClass myClass = (MutableDynaClass)myBean.getDynaClass();</code></br>
 *     <code>myClass.add("myMappedProperty", TreeMap.class);</code></br>
 *     <code>myBean.set("myMappedProperty", "myKey", "myValue");</code></br>
 *
 * <p><b><u><i>Restricted</i> DynaClass</u></b></p>
 *    <p><code>MutableDynaClass</code> have a facility to <i>restrict</i> the <code>DynaClass</code>
 *       so that its properties cannot be modified. If the <code>MutableDynaClass</code> is
 *       restricted then calling any of the <code>set()</code> methods for a property which
 *       doesn't exist will result in a <code>IllegalArgumentException</code> being thrown.</p>
 *
 * @see LazyDynaClass
 * @author Niall Pemberton
 */
public class LazyDynaBean implements DynaBean, Serializable {


   /**
    * Commons Logging
    */
    private transient Log logger = LogFactory.getLog(LazyDynaBean.class);

    /** BigInteger Zero */
    protected static final BigInteger BigInteger_ZERO = new BigInteger("0");
    /** BigDecimal Zero */
    protected static final BigDecimal BigDecimal_ZERO = new BigDecimal("0");
    /** Character Space */
    protected static final Character  Character_SPACE = new Character(' ');
    /** Byte Zero */
    protected static final Byte       Byte_ZERO       = new Byte((byte)0);
    /** Short Zero */
    protected static final Short      Short_ZERO      = new Short((short)0);
    /** Integer Zero */
    protected static final Integer    Integer_ZERO    = new Integer(0);
    /** Long Zero */
    protected static final Long       Long_ZERO       = new Long(0);
    /** Float Zero */
    protected static final Float      Float_ZERO      = new Float((byte)0);
    /** Double Zero */
    protected static final Double     Double_ZERO     = new Double((byte)0);

    /**
     * The <code>MutableDynaClass</code> "base class" that this DynaBean
     * is associated with.
     */
    protected Map values;

    /** Map decorator for this DynaBean */
    private transient Map mapDecorator;

    /**
     * The <code>MutableDynaClass</code> "base class" that this DynaBean
     * is associated with.
     */
    protected MutableDynaClass dynaClass;


    // ------------------- Constructors ----------------------------------

    /**
     * Construct a new <code>LazyDynaBean</code> with a <code>LazyDynaClass</code> instance.
     */
    public LazyDynaBean() {
        this(new LazyDynaClass());
    }

    /**
     * Construct a new <code>LazyDynaBean</code> with a <code>LazyDynaClass</code> instance.
     *
     * @param name Name of this DynaBean class
     */
    public LazyDynaBean(String name) {
        this(new LazyDynaClass(name));
    }

    /**
     * Construct a new <code>DynaBean</code> associated with the specified
     * <code>DynaClass</code> instance - if its not a <code>MutableDynaClass</code>
     * then a new <code>LazyDynaClass</code> is created and the properties copied.
     *
     * @param dynaClass The DynaClass we are associated with
     */
    public LazyDynaBean(DynaClass dynaClass) {

        values = newMap();

        if (dynaClass instanceof MutableDynaClass) {
            this.dynaClass = (MutableDynaClass)dynaClass;
        } else {
            this.dynaClass = new LazyDynaClass(dynaClass.getName(), dynaClass.getDynaProperties());
        }

    }


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

    /**
     * Return a Map representation of this DynaBean.
     * </p>
     * This, for example, could be used in JSTL in the following way to access
     * a DynaBean's <code>fooProperty</code>:
     * <ul><li><code>${myDynaBean.<b>map</b>.fooProperty}</code></li></ul>
     *
     * @return a Map representation of this DynaBean
     */
    public Map getMap() {
        // cache the Map
        if (mapDecorator == null) {
            mapDecorator = new DynaBeanMapDecorator(this);
        }
        return mapDecorator;
    }

    /**
     * <p>Return the size of an indexed or mapped property.</p>
     *
     * @param name Name of the property
     * @return The indexed or mapped property size
     * @exception IllegalArgumentException if no property name is specified
     */
    public int size(String name) {

        if (name == null) {
            throw new IllegalArgumentException("No property name specified");
        }

        Object value = values.get(name);
        if (value == null) {
            return 0;
        }

        if (value instanceof Map) {
            return ((Map)value).size();
        }

        if (value instanceof List) {
            return ((List)value).size();
        }

        if ((value.getClass().isArray())) {
            return Array.getLength(value);
        }

        return 0;

    }

    // ------------------- DynaBean Methods ----------------------------------

    /**
     * Does the specified mapped property contain a value for the specified
     * key value?
     *
     * @param name Name of the property to check
     * @param key Name of the key to check
     * @return <code>true<code> if the mapped property contains a value for
     * the specified key, otherwise <code>false</code>
     *
     * @exception IllegalArgumentException if no property name is specified
     */
    public boolean contains(String name, String key) {

        if (name == null) {
            throw new IllegalArgumentException("No property name specified");
        }

        Object value = values.get(name);
        if (value == null) {
            return false;
        }

        if (value instanceof Map) {
            return (((Map) value).containsKey(key));
        }

        return false;

    }

    /**
     * <p>Return the value of a simple property with the specified name.</p>
     *
     * <p><strong>N.B.</strong> Returns <code>null</code> if there is no property
     *  of the specified name.</p>
     *
     * @param name Name of the property whose value is to be retrieved.
     * @return The property's value
     * @exception IllegalArgumentException if no property name is specified
     */
    public Object get(String name) {

        if (name == null) {
            throw new IllegalArgumentException("No property name specified");
        }

        // Value found
        Object value = values.get(name);
        if (value != null) {
            return value;
        }

        // Property doesn't exist
        if (!isDynaProperty(name)) {
            return null;
        }

        // Property doesn't exist
        value = createProperty(name, dynaClass.getDynaProperty(name).getType());

        if (value != null) {
            set(name, value);
        }