001/* java.beans.beancontext.BeanContext 002 Copyright (C) 1999 Free Software Foundation, Inc. 003 004This file is part of GNU Classpath. 005 006GNU Classpath is free software; you can redistribute it and/or modify 007it under the terms of the GNU General Public License as published by 008the Free Software Foundation; either version 2, or (at your option) 009any later version. 010 011GNU Classpath is distributed in the hope that it will be useful, but 012WITHOUT ANY WARRANTY; without even the implied warranty of 013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014General Public License for more details. 015 016You should have received a copy of the GNU General Public License 017along with GNU Classpath; see the file COPYING. If not, write to the 018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 01902110-1301 USA. 020 021Linking this library statically or dynamically with other modules is 022making a combined work based on this library. Thus, the terms and 023conditions of the GNU General Public License cover the whole 024combination. 025 026As a special exception, the copyright holders of this library give you 027permission to link this library with independent modules to produce an 028executable, regardless of the license terms of these independent 029modules, and to copy and distribute the resulting executable under 030terms of your choice, provided that you also meet, for each linked 031independent module, the terms and conditions of the license of that 032module. An independent module is a module which is not derived from 033or based on this library. If you modify this library, you may extend 034this exception to your version of the library, but you are not 035obligated to do so. If you do not wish to do so, delete this 036exception statement from your version. */ 037 038 039package java.beans.beancontext; 040 041import java.beans.DesignMode; 042import java.beans.Visibility; 043import java.io.IOException; 044import java.io.InputStream; 045import java.net.URL; 046import java.util.Collection; 047 048/** 049 * Acts as a container for sub-beans and as a sub-bean, 050 * so that an entire hierarchy of beans can be made up of 051 * <code>BeanContext</code>s. 052 * <P> 053 * 054 * Since I can't sprinkle the <code>Collections</code> interface 055 * documentation with special information for <code>BeanContext</code> 056 * implementors, I'll have to document special requirements for 057 * implementors of those functions here. 058 * <P> 059 * 060 * <code><strong>add()</strong></code> or <code>addAll()</code>: 061 * <br> 062 * <OL> 063 * <LI> 064 * May add any <code>Object</code> into the hierarchy as well as a 065 * <code>BeanContextChild</code>, <code>BeanContext</code> or 066 * <code>BeanContextProxy</code> object. 067 * This way, any Bean can be in the hierarchy. 068 * </LI> 069 * <LI> 070 * Must synchronize on <code>BeanContext.globalHierarchyLock</code>. 071 * </LI> 072 * <LI> 073 * Don't add the <code>Object</code> if it's already there (only once 074 * per <code>BeanContext</code>). 075 * </LI> 076 * <LI> 077 * If it is a <code>BeanContextChild</code> implementor, call 078 * <code>setBeanContext()</code> on it. If it's a 079 * <code>BeanContextProxy</code> implementor, call 080 * <code>getBeanContextProxy().setBeanContext()</code> on it. 081 * If <code>setBeanContext()</code> vetoes the change, back out 082 * all changes so far and throw <code>IllegalStateException</code>. 083 * </LI> 084 * <LI> 085 * If it (or its proxy) implements <code>Visibility</code>, call 086 * <code>dontUseGui()</code> or <code>okToUseGui()</code> on it, 087 * depending on whether you (the <code>BeanContext</code>) feel like 088 * allowing it to use the GUI or not. 089 * </LI> 090 * <LI> 091 * If it implements <code>BeanContextChild</code> or 092 * <code>BeanContextProxy</code>, register yourself (the 093 * <code>BeanContext</code>) as both a 094 * <code>PropertyChangeListener</code> and 095 * <code>VetoableChangeListener</code> on the "beanContext" 096 * property (it may also add itself on any other properties it wishes 097 * to). 098 * </LI> 099 * <LI> 100 * If it is a listener or event source that you (the 101 * <code>BeanContext</code>) are interested in, you may register 102 * yourself to it or register it to you. 103 * </LI> 104 * <LI> 105 * Fire a <code>java.beans.beancontext.BeanContextMembershipEvent</code> 106 * before exiting. <code>addAll()</code> should wait until everything 107 * is done changing before firing the event (or events) so that if a 108 * failure occurs, the backing-out process can proceed without any 109 * events being fired at all. 110 * </LI> 111 * </OL> 112 * <P> 113 * 114 * <code><strong>remove()</strong></code> or <code>removeAll()</code>: 115 * <br> 116 * <OL> 117 * <LI> 118 * Must synchronize on <code>BeanContext.globalHierarchyLock</code>. 119 * </LI> 120 * <LI> 121 * If the specified <code>Object</code> is not a child of this 122 * <code>BeanContext</code>, just exit without performing any actions. 123 * </LI> 124 * <LI> 125 * Remove the <code>Object</code> from your collection of children. 126 * </LI> 127 * <LI> 128 * If it is a <code>BeanContextChild</code> implementor, call 129 * <code>setBeanContext(null)</code> on it. If it's a 130 * <code>BeanContextProxy</code> implementor, call 131 * <code>getBeanContextProxy().setBeanContext(null)</code> on it. 132 * If <code>setBeanContext()</code> vetoes the change, back out 133 * all changes so far and throw <code>IllegalStateException</code>. 134 * </LI> 135 * <LI> 136 * If you registered the <code>Object</code> to listen to you or 137 * registered yourself as a listener on the <code>Object</code> during 138 * <code>add()</code> or <code>addAll()</code>, undo the registration 139 * bycalling the appropriate <code>removeListener()</code> method. 140 * </LI> 141 * <LI> 142 * Fire a <code>java.beans.beancontext.BeanContextMembershipEvent</code> 143 * before exiting. <code>removeAll()</code> should wait until 144 * everything is done changing before firing the event (or events) so 145 * that if a failure occurs, the backing-out process can proceed 146 * without any events being fired at all. 147 * </LI> 148 * </OL> 149 * <P> 150 * 151 * <code>addAll()</code>, <code>removeAll()</code>, 152 * <code>retainAll()</code> and <code>clear()</code> do not need to be 153 * implemented, but may be if so desired. 154 * <P> 155 * 156 * Similarly, <code>Visibility</code> and <code>DesignMode</code> methods 157 * should propagate changed values to children that implement interfaces 158 * of the same name. 159 * <P> 160 * 161 * A hierarchy of beans is mainly useful so that different sets of beans 162 * can be established, each with their own set of resources. 163 * 164 * @author John Keiser 165 * @since JDK1.2 166 */ 167 168public interface BeanContext 169 extends Collection, BeanContextChild, Visibility, DesignMode { 170 171 /** 172 * The global lock on changing any BeanContext hierarchy. 173 * It kinda sucks that there is only one lock, since there can be 174 * multiple hierarchies. Oh well, I didn't design, I just code. 175 * <P> 176 * 177 * Methods that must (or do) synchronize on the global lock: 178 * <BR> 179 * <UL> 180 * <LI> 181 * Implementors of <CODE>BeanContext.add()</CODE> and <code>addAll()</code> 182 * </LI> 183 * </UL> 184 * @fixme fill in the rest of the methods which use the global lock. 185 */ 186 Object globalHierarchyLock = new Object(); 187 188 /** 189 * Instantiate a Bean using this Bean's <code>ClassLoader</code> 190 * and this <code>BeanContext</code> as the parent. 191 * <P> 192 * 193 * This method exists mainly so that <code>BeanContext</code> 194 * implementations can perform extra actions on Beans that are 195 * created within them. 196 * 197 * @param beanName the name of the bean to instantiate 198 * @return the created Bean 199 * 200 * @see java.beans.Beans#instantiate(java.lang.ClassLoader,java.lang.String) 201 * @see java.beans.Beans#instantiate(java.lang.ClassLoader,java.lang.String,java.beans.beancontext.BeanContext) 202 * @exception IOException if there is an I/O problem during 203 * instantiation. 204 * @exception ClassNotFoundException if a serialized Bean's class 205 * is not found. 206 */ 207 Object instantiateChild(String beanName) 208 throws IOException, 209 ClassNotFoundException; 210 211 /** 212 * Get a resource. The <code>BeanContext</code> will typically 213 * call <code>ClassLoader.getResource()</code>, but may do it any 214 * way it wants to. This allows a <code>BeanContext</code> to 215 * have its own set of resources separate from the rest of the 216 * system. 217 * <P> 218 * 219 * Beans should call this method on their parent rather than the 220 * associated <code>ClassLoader</code> method. 221 * <P> 222 * 223 * I am assuming, but am not entirely sure, that if a 224 * <code>BeanContext</code> cannot find a resource, its 225 * responsibility is to call the <code>getResource</code> method 226 * of its parent <code>BeanContext</code>. 227 * 228 * @return a URL to the requested resource. 229 * @param resourceName the name of the resource requested. 230 * @param requestor a reference to the child requesting the resource. 231 * @see java.lang.ClassLoader#getResource(java.lang.String) 232 */ 233 URL getResource(String resourceName, BeanContextChild requestor); 234 235 /** 236 * Get a resource as a stream. The <code>BeanContext</code> will 237 * typically call <code>ClassLoader.getResourceAsStream()</code>, 238 * but may do it any way it wants to. This allows a 239 * <code>BeanContext</code>'s children to have their own set of 240 * resources separate from the rest of the system. 241 * <P> 242 * 243 * Beans should call this method on their parent rather than the 244 * associated <code>ClassLoader</code> method. 245 * <P> 246 * 247 * I am assuming, but am not entirely sure, that if a 248 * <code>BeanContext</code> cannot find a resource, its 249 * responsibility is to call the <code>getResourceAsStream</code> 250 * method of its parent <code>BeanContext</code>. 251 * 252 * @return the requested resource as a stream. 253 * @param resourceName the name of the resource requested. 254 * @param requestor a reference to the child requesting the resource. 255 * @see java.lang.ClassLoader#getResourceAsStream(java.lang.String) 256 */ 257 InputStream getResourceAsStream(String resourceName, BeanContextChild requestor); 258 259 /** 260 * Add a listener on changes to the membership of this 261 * <code>BeanContext</code> object. 262 * @param listener the listener to add. 263 */ 264 void addBeanContextMembershipListener(BeanContextMembershipListener listener); 265 266 /** 267 * Remove a listener on changes to the membership of this 268 * <code>BeanContext</code> object. 269 * @param listener the listener to remove. 270 */ 271 void removeBeanContextMembershipListener(BeanContextMembershipListener listener); 272}