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    1   /*
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements.  See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache License, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License.  You may obtain a copy of the License at
    8    *
    9    *      http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   */
    17
    18
    19  package org.apache.commons.beanutils;
    20
    21
    22  import java.io.Serializable;
    23  import java.lang.reflect.Constructor;
    24  import java.lang.reflect.InvocationTargetException;
    25  import java.util.HashMap;
    26
    27
    28  /***
    29   * <p>Minimal implementation of the <code>DynaClass</code> interface.  Can be
    30   * used as a convenience base class for more sophisticated implementations.</p> *
    31   * <p><strong>IMPLEMENTATION NOTE</strong> - The <code>DynaBean</code>
    32   * implementation class supplied to our constructor MUST have a one-argument
    33   * constructor of its own that accepts a <code>DynaClass</code>.  This is
    34   * used to associate the DynaBean instance with this DynaClass.</p>
    35   *
    36   * @author Craig McClanahan
    37   * @version $Revision: 556229 $ $Date: 2007-07-14 07:11:19 +0100 (Sat, 14 Jul 2007) $
    38   */
    39
    40  public class BasicDynaClass implements DynaClass, Serializable {
    41
    42
    43      // ----------------------------------------------------------- Constructors
    44
    45
    46      /***
    47       * Construct a new BasicDynaClass with default parameters.
    48       */
    49      public BasicDynaClass() {
    50
    51          this(null, null, null);
    52
    53      }
    54
    55
    56      /***
    57       * Construct a new BasicDynaClass with the specified parameters.
    58       *
    59       * @param name Name of this DynaBean class
    60       * @param dynaBeanClass The implementation class for new instances
    61       */
    62      public BasicDynaClass(String name, Class dynaBeanClass) {
    63
    64          this(name, dynaBeanClass, null);
    65
    66      }
    67
    68
    69      /***
    70       * Construct a new BasicDynaClass with the specified parameters.
    71       *
    72       * @param name Name of this DynaBean class
    73       * @param dynaBeanClass The implementation class for new intances
    74       * @param properties Property descriptors for the supported properties
    75       */
    76      public BasicDynaClass(String name, Class dynaBeanClass,
    77                            DynaProperty[] properties) {
    78
    79          super();
    80          if (name != null) {
    81              this.name = name;
    82          }
    83          if (dynaBeanClass == null) {
    84              dynaBeanClass = BasicDynaBean.class;
    85          }
    86          setDynaBeanClass(dynaBeanClass);
    87          if (properties != null) {
    88              setProperties(properties);
    89          }
    90
    91      }
    92
    93
    94      // ----------------------------------------------------- Instance Variables
    95
    96
    97      /***
    98       * The constructor of the <code>dynaBeanClass</code> that we will use
    99       * for creating new instances.
    100      */
    101     protected transient Constructor constructor = null;
    102
    103
    104     /***
    105      * The method signature of the constructor we will use to create
    106      * new DynaBean instances.
    107      */
    108     protected static Class[] constructorTypes = { DynaClass.class };
    109
    110
    111     /***
    112      * The argument values to be passed to the constructore we will use
    113      * to create new DynaBean instances.
    114      */
    115     protected Object[] constructorValues = { this };
    116
    117
    118     /***
    119      * The <code>DynaBean</code> implementation class we will use for
    120      * creating new instances.
    121      */
    122     protected Class dynaBeanClass = BasicDynaBean.class;
    123
    124
    125     /***
    126      * The "name" of this DynaBean class.
    127      */
    128     protected String name = this.getClass().getName();
    129
    130
    131     /***
    132      * The set of dynamic properties that are part of this DynaClass.
    133      */
    134     protected DynaProperty[] properties = new DynaProperty[0];
    135
    136
    137     /***
    138      * The set of dynamic properties that are part of this DynaClass,
    139      * keyed by the property name.  Individual descriptor instances will
    140      * be the same instances as those in the <code>properties</code> list.
    141      */
    142     protected HashMap propertiesMap = new HashMap();
    143
    144
    145     // ------------------------------------------------------ DynaClass Methods
    146
    147
    148     /***
    149      * Return the name of this DynaClass (analogous to the
    150      * <code>getName()</code> method of <code>java.lang.Class</code), which
    151      * allows the same <code>DynaClass</code> implementation class to support
    152      * different dynamic classes, with different sets of properties.
    153      *
    154      * @return the name of the DynaClass
    155      */
    156     public String getName() {
    157
    158         return (this.name);
    159
    160     }
    161
    162
    163     /***
    164      * Return a property descriptor for the specified property, if it exists;
    165      * otherwise, return <code>null</code>.
    166      *
    167      * @param name Name of the dynamic property for which a descriptor
    168      *  is requested
    169      * @return The descriptor for the specified property
    170      *
    171      * @exception IllegalArgumentException if no property name is specified
    172      */
    173     public DynaProperty getDynaProperty(String name) {
    174
    175         if (name == null) {
    176             throw new IllegalArgumentException
    177                     ("No property name specified");
    178         }
    179         return ((DynaProperty) propertiesMap.get(name));
    180
    181     }
    182
    183
    184     /***
    185      * <p>Return an array of <code>ProperyDescriptors</code> for the properties
    186      * currently defined in this DynaClass.  If no properties are defined, a
    187      * zero-length array will be returned.</p>
    188      *
    189      * <p><strong>FIXME</strong> - Should we really be implementing
    190      * <code>getBeanInfo()</code> instead, which returns property descriptors
    191      * and a bunch of other stuff?</p>
    192      *
    193      * @return the set of properties for this DynaClass
    194      */
    195     public DynaProperty[] getDynaProperties() {
    196
    197         return (properties);
    198
    199     }
    200
    201
    202     /***
    203      * Instantiate and return a new DynaBean instance, associated
    204      * with this DynaClass.
    205      *
    206      * @return A new <code>DynaBean</code> instance
    207      * @exception IllegalAccessException if the Class or the appropriate
    208      *  constructor is not accessible
    209      * @exception InstantiationException if this Class represents an abstract
    210      *  class, an array class, a primitive type, or void; or if instantiation
    211      *  fails for some other reason
    212      */
    213     public DynaBean newInstance()
    214             throws IllegalAccessException, InstantiationException {
    215
    216         try {
    217             // Refind the constructor after a deserialization (if needed)
    218             if (constructor == null) {
    219                 setDynaBeanClass(this.dynaBeanClass);
    220             }
    221             // Invoke the constructor to create a new bean instance
    222             return ((DynaBean) constructor.newInstance(constructorValues));
    223         } catch (InvocationTargetException e) {
    224             throw new InstantiationException
    225                     (e.getTargetException().getMessage());
    226         }
    227
    228     }
    229
    230
    231     // --------------------------------------------------------- Public Methods
    232
    233
    234     /***
    235      * Return the Class object we will use to create new instances in the
    236      * <code>newInstance()</code> method.  This Class <strong>MUST</strong>
    237      * implement the <code>DynaBean</code> interface.
    238      *
    239      * @return The class of the {@link DynaBean}
    240      */
    241     public Class getDynaBeanClass() {
    242
    243         return (this.dynaBeanClass);
    244
    245     }
    246
    247
    248     // ------------------------------------------------------ Protected Methods
    249
    250
    251     /***
    252      * Set the Class object we will use to create new instances in the
    253      * <code>newInstance()</code> method.  This Class <strong>MUST</strong>
    254      * implement the <code>DynaBean</code> interface.
    255      *
    256      * @param dynaBeanClass The new Class object
    257      *
    258      * @exception IllegalArgumentException if the specified Class does not
    259      *  implement the <code>DynaBean</code> interface
    260      */
    261     protected void setDynaBeanClass(Class dynaBeanClass) {
    262
    263         // Validate the argument type specified
    264         if (dynaBeanClass.isInterface()) {
    265             throw new IllegalArgumentException
    266                     ("Class " + dynaBeanClass.getName() +
    267                     " is an interface, not a class");
    268         }
    269         if (!DynaBean.class.isAssignableFrom(dynaBeanClass)) {
    270             throw new IllegalArgumentException
    271                     ("Class " + dynaBeanClass.getName() +
    272                     " does not implement DynaBean");
    273         }
    274
    275         // Identify the Constructor we will use in newInstance()
    276         try {
    277             this.constructor = dynaBeanClass.getConstructor(constructorTypes);
    278         } catch (NoSuchMethodException e) {
    279             throw new IllegalArgumentException
    280                     ("Class " + dynaBeanClass.getName() +
    281                     " does not have an appropriate constructor");
    282         }
    283         this.dynaBeanClass = dynaBeanClass;
    284
    285     }
    286
    287
    288     /***
    289      * Set the list of dynamic properties supported by this DynaClass.
    290      *
    291      * @param properties List of dynamic properties to be supported
    292      */
    293     protected void setProperties(DynaProperty[] properties) {
    294
    295         this.properties = properties;
    296         propertiesMap.clear();
    297         for (int i = 0; i < properties.length; i++) {
    298             propertiesMap.put(properties[i].getName(), properties[i]);
    299         }
    300
    301     }
    302
    303
    304 }