| 1 | /* |
| 2 | * Copyright (C) Christian Schulte, 2012-22 |
| 3 | * All rights reserved. |
| 4 | * |
| 5 | * Redistribution and use in source and binary forms, with or without |
| 6 | * modification, are permitted provided that the following conditions |
| 7 | * are met: |
| 8 | * |
| 9 | * o Redistributions of source code must retain the above copyright |
| 10 | * notice, this list of conditions and the following disclaimer. |
| 11 | * |
| 12 | * o Redistributions in binary form must reproduce the above copyright |
| 13 | * notice, this list of conditions and the following disclaimer in |
| 14 | * the documentation and/or other materials provided with the |
| 15 | * distribution. |
| 16 | * |
| 17 | * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, |
| 18 | * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY |
| 19 | * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL |
| 20 | * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| 26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 27 | * |
| 28 | * $JOMC: ModelContextFactory.java 4760 2013-04-08 17:56:26Z schulte $ |
| 29 | * |
| 30 | */ |
| 31 | package org.jomc.modlet; |
| 32 | |
| 33 | import java.security.AccessController; |
| 34 | import java.security.PrivilegedAction; |
| 35 | import java.text.MessageFormat; |
| 36 | import java.util.Locale; |
| 37 | import java.util.ResourceBundle; |
| 38 | |
| 39 | /** |
| 40 | * Interface to creating model contexts. |
| 41 | * |
| 42 | * @author <a href="mailto:cs@schulte.it">Christian Schulte</a> |
| 43 | * @version $JOMC: ModelContextFactory.java 4760 2013-04-08 17:56:26Z schulte $ |
| 44 | * @since 1.2 |
| 45 | */ |
| 46 | public abstract class ModelContextFactory |
| 47 | { |
| 48 | |
| 49 | /** Constant for the name of the default {@code ModelContextFactory} implementation. */ |
| 50 | private static final String DEFAULT_MODEL_CONTEXT_FACTORY_CLASS_NAME = "org.jomc.modlet.DefaultModelContextFactory"; |
| 51 | |
| 52 | /** Constant for the name of the system property controlling {@code ModelContextFactory} implementations. */ |
| 53 | private static final String MODEL_CONTEXT_FACTORY_CLASS_NAME_PROPERTY = |
| 54 | "org.jomc.modlet.ModelContextFactory"; |
| 55 | |
| 56 | /** Creates a new {@code ModelContextFactory} instance. */ |
| 57 | protected ModelContextFactory() |
| 58 | { |
| 59 | super(); |
| 60 | } |
| 61 | |
| 62 | /** |
| 63 | * Creates a new {@code ModelContextFactory} instance. |
| 64 | * <p>The name of the class providing the {@code ModelContextFactory} implementation loaded by this method is |
| 65 | * controlled by system property {@code org.jomc.modlet.ModelContextFactory}. If that property is not set, this |
| 66 | * methods returns a new default instance.</p> |
| 67 | * |
| 68 | * @return A new {@code ModelContextFactory} instance. |
| 69 | * |
| 70 | * @throws ModelContextFactoryError if creating a new instance fails. |
| 71 | */ |
| 72 | public static ModelContextFactory newInstance() throws ModelContextFactoryError |
| 73 | { |
| 74 | return newInstance( AccessController.doPrivileged( new PrivilegedAction<String>() |
| 75 | { |
| 76 | |
| 77 | public String run() |
| 78 | { |
| 79 | return System.getProperty( MODEL_CONTEXT_FACTORY_CLASS_NAME_PROPERTY, |
| 80 | DEFAULT_MODEL_CONTEXT_FACTORY_CLASS_NAME ); |
| 81 | |
| 82 | } |
| 83 | |
| 84 | } ) ); |
| 85 | } |
| 86 | |
| 87 | /** |
| 88 | * Creates a new {@code ModelContextFactory} instance. |
| 89 | * |
| 90 | * @param factoryClassName The name of the {@code ModelContextFactory} class to create an instance of. |
| 91 | * |
| 92 | * @return A new {@code ModelContextFactory} instance. |
| 93 | * |
| 94 | * @throws NullPointerException if {@code factoryClassName} is {@code null}. |
| 95 | * @throws ModelContextFactoryError if creating a new instance fails. |
| 96 | */ |
| 97 | public static ModelContextFactory newInstance( final String factoryClassName ) throws ModelContextFactoryError |
| 98 | { |
| 99 | if ( factoryClassName == null ) |
| 100 | { |
| 101 | throw new NullPointerException( "factoryClassName" ); |
| 102 | } |
| 103 | |
| 104 | try |
| 105 | { |
| 106 | final Class<?> factoryClass = Class.forName( factoryClassName ); |
| 107 | |
| 108 | if ( !ModelContextFactory.class.isAssignableFrom( factoryClass ) ) |
| 109 | { |
| 110 | throw new ModelContextFactoryError( getMessage( "illegalFactory", factoryClassName, |
| 111 | ModelContextFactory.class.getName() ) ); |
| 112 | |
| 113 | } |
| 114 | |
| 115 | return factoryClass.asSubclass( ModelContextFactory.class ).newInstance(); |
| 116 | } |
| 117 | catch ( final ClassNotFoundException e ) |
| 118 | { |
| 119 | throw new ModelContextFactoryError( getMessage( "classNotFound", factoryClassName ), e ); |
| 120 | } |
| 121 | catch ( final InstantiationException e ) |
| 122 | { |
| 123 | final String message = getMessage( e ); |
| 124 | throw new ModelContextFactoryError( getMessage( "instantiationException", factoryClassName, |
| 125 | message != null ? " " + message : "" ), e ); |
| 126 | |
| 127 | } |
| 128 | catch ( final IllegalAccessException e ) |
| 129 | { |
| 130 | final String message = getMessage( e ); |
| 131 | throw new ModelContextFactoryError( getMessage( "accessDenied", factoryClassName, |
| 132 | message != null ? " " + message : "" ), e ); |
| 133 | |
| 134 | } |
| 135 | } |
| 136 | |
| 137 | /** |
| 138 | * Creates a new {@code ModelContext} instance. |
| 139 | * |
| 140 | * @return A new {@code ModelContext} instance. |
| 141 | */ |
| 142 | public abstract ModelContext newModelContext(); |
| 143 | |
| 144 | /** |
| 145 | * Creates a new {@code ModelContext} instance. |
| 146 | * |
| 147 | * @param classLoader The class loader to create a new instance with or {@code null}, to create a new instance |
| 148 | * using the bootstrap class loader. |
| 149 | * |
| 150 | * @return A new {@code ModelContext} instance for {@code classLoader}. |
| 151 | */ |
| 152 | public abstract ModelContext newModelContext( final ClassLoader classLoader ); |
| 153 | |
| 154 | private static String getMessage( final String key, final Object... args ) |
| 155 | { |
| 156 | return MessageFormat.format( ResourceBundle.getBundle( ModelContextFactory.class.getName().replace( '.', '/' ), |
| 157 | Locale.getDefault() ).getString( key ), args ); |
| 158 | |
| 159 | } |
| 160 | |
| 161 | private static String getMessage( final Throwable t ) |
| 162 | { |
| 163 | return t != null |
| 164 | ? t.getMessage() != null && t.getMessage().trim().length() > 0 |
| 165 | ? t.getMessage() |
| 166 | : getMessage( t.getCause() ) |
| 167 | : null; |
| 168 | |
| 169 | } |
| 170 | |
| 171 | } |