| 1 | /* |
| 2 | * jDTAUS Core API |
| 3 | * Copyright (C) 2005 Christian Schulte |
| 4 | * <cs@schulte.it> |
| 5 | * |
| 6 | * This library is free software; you can redistribute it and/or |
| 7 | * modify it under the terms of the GNU Lesser General Public |
| 8 | * License as published by the Free Software Foundation; either |
| 9 | * version 2.1 of the License, or any later version. |
| 10 | * |
| 11 | * This library is distributed in the hope that it will be useful, |
| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 14 | * Lesser General Public License for more details. |
| 15 | * |
| 16 | * You should have received a copy of the GNU Lesser General Public |
| 17 | * License along with this library; if not, write to the Free Software |
| 18 | * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
| 19 | * |
| 20 | */ |
| 21 | package org.jdtaus.core.container; |
| 22 | |
| 23 | import java.lang.reflect.Constructor; |
| 24 | import java.lang.reflect.InvocationTargetException; |
| 25 | import java.lang.reflect.Method; |
| 26 | |
| 27 | /** |
| 28 | * Factory for the {@code Model} singleton. |
| 29 | * |
| 30 | * @author <a href="mailto:cs@schulte.it">Christian Schulte</a> |
| 31 | * @version $JDTAUS: ModelFactory.java 8743 2012-10-07 03:06:20Z schulte $ |
| 32 | */ |
| 33 | public abstract class ModelFactory |
| 34 | { |
| 35 | //--Constants--------------------------------------------------------------- |
| 36 | |
| 37 | /** Default {@code Model} implementation. */ |
| 38 | private static final String DEFAULT_MODEL = |
| 39 | "org.jdtaus.core.container.ri.client.DefaultModel"; |
| 40 | |
| 41 | /** Empty array. */ |
| 42 | private static final Class[] EMPTY = |
| 43 | { |
| 44 | }; |
| 45 | |
| 46 | //---------------------------------------------------------------Constants-- |
| 47 | //--ModelFactory------------------------------------------------------------ |
| 48 | |
| 49 | /** Default singleton instance. */ |
| 50 | private static Model instance; |
| 51 | |
| 52 | /** |
| 53 | * Gets the {@code Model} singleton. |
| 54 | * <p>By default this class will instantiate a new instance and hold it in |
| 55 | * a static class variable as the singleton to return for other calls. This |
| 56 | * behaviour can be changed by setting a system property with key |
| 57 | * {@code org.jdtaus.core.container.ModelFactory} to the name of a |
| 58 | * class defining a {@code public static Model getModel()} method |
| 59 | * returning the singleton instance of the model.</p> |
| 60 | * |
| 61 | * @return the singleton {@code Model} instance. |
| 62 | * |
| 63 | * @throws ModelError for unrecoverable model errors. |
| 64 | * |
| 65 | * @see ModelFactory#newModel() |
| 66 | */ |
| 67 | public static Model getModel() |
| 68 | { |
| 69 | Object ret = null; |
| 70 | final String factory = System.getProperty( |
| 71 | ModelFactory.class.getName() ); |
| 72 | |
| 73 | try |
| 74 | { |
| 75 | if ( factory != null ) |
| 76 | { |
| 77 | // Call getModel() on that class. |
| 78 | final Class clazz = ClassLoaderFactory.loadClass( |
| 79 | ModelFactory.class, factory ); |
| 80 | |
| 81 | final Method meth = clazz.getDeclaredMethod( "getModel", |
| 82 | EMPTY ); |
| 83 | |
| 84 | ret = meth.invoke( null, EMPTY ); |
| 85 | } |
| 86 | else |
| 87 | { |
| 88 | if ( instance == null ) |
| 89 | { |
| 90 | instance = newModel(); |
| 91 | } |
| 92 | |
| 93 | ret = instance; |
| 94 | } |
| 95 | |
| 96 | return (Model) ret; |
| 97 | } |
| 98 | catch ( final SecurityException e ) |
| 99 | { |
| 100 | throw new ModelError( e ); |
| 101 | } |
| 102 | catch ( final NoSuchMethodException e ) |
| 103 | { |
| 104 | throw new ModelError( e ); |
| 105 | } |
| 106 | catch ( final IllegalAccessException e ) |
| 107 | { |
| 108 | throw new ModelError( e ); |
| 109 | } |
| 110 | catch ( final InvocationTargetException e ) |
| 111 | { |
| 112 | final Throwable targetException = e.getTargetException(); |
| 113 | |
| 114 | if ( targetException instanceof Error ) |
| 115 | { |
| 116 | throw (Error) targetException; |
| 117 | } |
| 118 | else if ( targetException instanceof RuntimeException ) |
| 119 | { |
| 120 | throw (RuntimeException) targetException; |
| 121 | } |
| 122 | else |
| 123 | { |
| 124 | throw new ModelError( targetException == null |
| 125 | ? e |
| 126 | : targetException ); |
| 127 | |
| 128 | } |
| 129 | } |
| 130 | catch ( final ClassCastException e ) |
| 131 | { |
| 132 | throw new ModelError( e ); |
| 133 | } |
| 134 | catch ( final ClassNotFoundException e ) |
| 135 | { |
| 136 | throw new ModelError( e ); |
| 137 | } |
| 138 | } |
| 139 | |
| 140 | /** |
| 141 | * Creates a new instance of the configured {@code Model} implementation. |
| 142 | * <p>The implementation to be used can be controlled via a system property |
| 143 | * with key {@code org.jdtaus.core.container.Model} set to a class |
| 144 | * name to be loaded as the {@code Model} implementation.</p> |
| 145 | * <p>This method should be used by {@code getModel()} implementors to |
| 146 | * retrieve a new {@code Model} instance.</p> |
| 147 | * |
| 148 | * @return a new instance of the configured {@code Model} implementation. |
| 149 | * |
| 150 | * @throws ModelError for unrecoverable model errors. |
| 151 | */ |
| 152 | public static Model newModel() |
| 153 | { |
| 154 | Constructor ctor = null; |
| 155 | |
| 156 | try |
| 157 | { |
| 158 | final String className = System.getProperty( Model.class.getName(), |
| 159 | DEFAULT_MODEL ); |
| 160 | |
| 161 | final Class clazz = ClassLoaderFactory.loadClass( |
| 162 | ModelFactory.class, className ); |
| 163 | |
| 164 | ctor = clazz.getDeclaredConstructor( EMPTY ); |
| 165 | ctor.setAccessible( true ); |
| 166 | return (Model) ctor.newInstance( EMPTY ); |
| 167 | } |
| 168 | catch ( final SecurityException e ) |
| 169 | { |
| 170 | throw new ModelError( e ); |
| 171 | } |
| 172 | catch ( final NoSuchMethodException e ) |
| 173 | { |
| 174 | throw new ModelError( e ); |
| 175 | } |
| 176 | catch ( final IllegalArgumentException e ) |
| 177 | { |
| 178 | throw new ModelError( e ); |
| 179 | } |
| 180 | catch ( final IllegalAccessException e ) |
| 181 | { |
| 182 | throw new ModelError( e ); |
| 183 | } |
| 184 | catch ( final java.lang.InstantiationException e ) |
| 185 | { |
| 186 | throw new ModelError( e ); |
| 187 | } |
| 188 | catch ( final InvocationTargetException e ) |
| 189 | { |
| 190 | final Throwable targetException = e.getTargetException(); |
| 191 | |
| 192 | if ( targetException instanceof Error ) |
| 193 | { |
| 194 | throw (Error) targetException; |
| 195 | } |
| 196 | else if ( targetException instanceof RuntimeException ) |
| 197 | { |
| 198 | throw (RuntimeException) targetException; |
| 199 | } |
| 200 | else |
| 201 | { |
| 202 | throw new ModelError( targetException == null |
| 203 | ? e |
| 204 | : targetException ); |
| 205 | |
| 206 | } |
| 207 | } |
| 208 | catch ( final ClassCastException e ) |
| 209 | { |
| 210 | throw new ModelError( e ); |
| 211 | } |
| 212 | catch ( final ClassNotFoundException e ) |
| 213 | { |
| 214 | throw new ModelError( e ); |
| 215 | } |
| 216 | finally |
| 217 | { |
| 218 | if ( ctor != null ) |
| 219 | { |
| 220 | ctor.setAccessible( false ); |
| 221 | } |
| 222 | } |
| 223 | } |
| 224 | |
| 225 | //------------------------------------------------------------ModelFactory-- |
| 226 | } |