001 /* java.beans.beancontext.BeanContextServiceProvider 002 Copyright (C) 1999 Free Software Foundation, Inc. 003 004 This file is part of GNU Classpath. 005 006 GNU Classpath is free software; you can redistribute it and/or modify 007 it under the terms of the GNU General Public License as published by 008 the Free Software Foundation; either version 2, or (at your option) 009 any later version. 010 011 GNU Classpath is distributed in the hope that it will be useful, but 012 WITHOUT ANY WARRANTY; without even the implied warranty of 013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014 General Public License for more details. 015 016 You should have received a copy of the GNU General Public License 017 along with GNU Classpath; see the file COPYING. If not, write to the 018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 019 02110-1301 USA. 020 021 Linking this library statically or dynamically with other modules is 022 making a combined work based on this library. Thus, the terms and 023 conditions of the GNU General Public License cover the whole 024 combination. 025 026 As a special exception, the copyright holders of this library give you 027 permission to link this library with independent modules to produce an 028 executable, regardless of the license terms of these independent 029 modules, and to copy and distribute the resulting executable under 030 terms of your choice, provided that you also meet, for each linked 031 independent module, the terms and conditions of the license of that 032 module. An independent module is a module which is not derived from 033 or based on this library. If you modify this library, you may extend 034 this exception to your version of the library, but you are not 035 obligated to do so. If you do not wish to do so, delete this 036 exception statement from your version. */ 037 038 039 package java.beans.beancontext; 040 041 import java.util.Iterator; 042 043 /** 044 * An actual factory for services. 045 * <P> 046 * 047 * It is the <code>BeanContextServiceProvider</code>'s responsibility to 048 * register itself with whatever <code>BeanContextServices</code> object 049 * it wishes to provide services through using the 050 * <code>addService()</code> method. 051 * <P> 052 * 053 * If for some reason it can no longer provide services for a particular 054 * class, this class must invoke 055 * <code>BeanContextServices.revokeService(serviceClass,this,true)</code> 056 * for all the places it has registered the service. 057 * 058 * @author John Keiser 059 * @since JDK1.2 060 */ 061 062 public interface BeanContextServiceProvider { 063 /** 064 * Get a service. 065 * Called from <code>BeanContextServices.getService()</code>. 066 * 067 * <p>If the requested service class is not available, or if this 068 * <code>BeanContextServiceProvider</code> chooses not honor the 069 * request for some reason, then this method will return 070 * <code>null</code>.</p> 071 * 072 * This method may throw unchecked exceptions, so watch out. 073 * 074 * @param services the <code>BeanContextServices</code> that wants 075 * to get the service. Only weak references to this will 076 * be retained, and it will never be changed, only queried 077 * in a read-only manner. 078 * @param requestor the actual requestor of the service. Only 079 * weak references to this will be retained, and it will 080 * never be changed, only queried in a read-only manner. 081 * @param serviceClass the <code>Class</code> of the service being 082 * requested. 083 * @param serviceSelector a parameter to customize the service 084 * returned with. 085 * @return an instance of <code>serviceClass</code> (such that 086 * <code>instanceof</code> serviceClass is true), or 087 * <code>null</code>. 088 * @see java.beans.beancontext.BeanContextServices#getService(java.beans.beancontext.BeanContextChild,java.lang.Object,java.lang.Class,java.lang.Object,java.beans.beancontext.BeanContextServiceRevokedListener) 089 */ 090 Object getService(BeanContextServices services, Object requestor, Class serviceClass, Object serviceSelector); 091 092 /** 093 * Release the service. 094 * <P> 095 * 096 * Called by <code>BeanContextServices.releaseService()</code>. 097 * <P> 098 * 099 * Most <code>BeanContextServiceProvider</code>s won't have to do 100 * anything here. 101 * 102 * @param services the <code>BeanContextServices</code> that wants 103 * to release the service. Only weak references to this will 104 * be retained, and it will never be changed, only queried 105 * in a read-only manner. 106 * @param requestor the original requestor of the service. 107 * @param service the service to relinquish 108 * @see java.beans.beancontext.BeanContextServices#releaseService(java.beans.beancontext.BeanContextChild,java.lang.Object,java.lang.Object) 109 */ 110 void releaseService(BeanContextServices services, Object requestor, Object service); 111 112 /** 113 * Get a list of valid service selectors for the specified service class. 114 * This method is called from 115 * <code>BeanContextServices.getCurrentServiceSelectors()</code>. 116 * <P> 117 * 118 * If the specified service class does not have a finite number of 119 * valid service selectors, it should return <code>null</code>. 120 * If it takes a general <code>Integer</code> parameter, for 121 * example, you may as well return <code>null</code> or the poor 122 * soul who called this method will be iterating all day. 123 * <P> 124 * 125 * If it has no valid service selectors, it should still return an empty 126 * <code>Iterator</code>. 127 * 128 * @param services the <code>BeanContextServices</code> that wants 129 * to get the service selectors. Only weak references to this will 130 * be retained, and it will never be changed, only queried 131 * in a read-only manner. 132 * @param serviceClass the service class to get selectors for. 133 * @return a list of valid service selectors for the service 134 * class, or <code>null</code>. 135 * @see java.beans.beancontext.BeanContextServices#getCurrentServiceSelectors(java.lang.Class) 136 */ 137 Iterator getCurrentServiceSelectors(BeanContextServices services, Class serviceClass); 138 }