Source for java.beans.beancontext.BeanContextServiceProvider

   1: /* java.beans.beancontext.BeanContextServiceProvider
   2:    Copyright (C) 1999 Free Software Foundation, Inc.
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10:  
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: 
  39: package java.beans.beancontext;
  40: 
  41: import java.util.Iterator;
  42: 
  43: /**
  44:  * An actual factory for services.
  45:  * <P>
  46:  *
  47:  * It is the <code>BeanContextServiceProvider</code>'s responsibility to
  48:  * register itself with whatever <code>BeanContextServices</code> object
  49:  * it wishes to provide services through using the
  50:  * <code>addService()</code> method.
  51:  * <P>
  52:  *
  53:  * If for some reason it can no longer provide services for a particular
  54:  * class, this class must invoke
  55:  * <code>BeanContextServices.revokeService(serviceClass,this,true)</code>
  56:  * for all the places it has registered the service.
  57:  *
  58:  * @author John Keiser
  59:  * @since JDK1.2
  60:  */
  61: 
  62: public interface BeanContextServiceProvider {
  63:     /**
  64:      * Get a service.
  65:      * Called from <code>BeanContextServices.getService()</code>.
  66:      *
  67:      * <p>If the requested service class is not available, or if this
  68:      * <code>BeanContextServiceProvider</code> chooses not honor the
  69:      * request for some reason, then this method will return
  70:      * <code>null</code>.</p>
  71:      *
  72:      * This method may throw unchecked exceptions, so watch out.
  73:      *
  74:      * @param services the <code>BeanContextServices</code> that wants
  75:      *        to get the service.  Only weak references to this will
  76:      *        be retained, and it will never be changed, only queried
  77:      *        in a read-only manner.
  78:      * @param requestor the actual requestor of the service.  Only
  79:      *        weak references to this will be retained, and it will
  80:      *        never be changed, only queried in a read-only manner.
  81:      * @param serviceClass the <code>Class</code> of the service being
  82:      *        requested.
  83:      * @param serviceSelector a parameter to customize the service
  84:      *        returned with.
  85:      * @return an instance of <code>serviceClass</code> (such that
  86:      *        <code>instanceof</code> serviceClass is true), or
  87:      *        <code>null</code>.
  88:      * @see java.beans.beancontext.BeanContextServices#getService(java.beans.beancontext.BeanContextChild,java.lang.Object,java.lang.Class,java.lang.Object,java.beans.beancontext.BeanContextServiceRevokedListener)
  89:      */
  90:     Object getService(BeanContextServices services, Object requestor, Class serviceClass, Object serviceSelector);
  91: 
  92:     /**
  93:      * Release the service.
  94:      * <P>
  95:      *
  96:      * Called by <code>BeanContextServices.releaseService()</code>.
  97:      * <P>
  98:      *
  99:      * 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: }