001// Copyright 2005 The Apache Software Foundation 002// 003// Licensed under the Apache License, Version 2.0 (the "License"); 004// you may not use this file except in compliance with the License. 005// You may obtain a copy of the License at 006// 007// http://www.apache.org/licenses/LICENSE-2.0 008// 009// Unless required by applicable law or agreed to in writing, software 010// distributed under the License is distributed on an "AS IS" BASIS, 011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 012// See the License for the specific language governing permissions and 013// limitations under the License. 014 015package org.apache.tapestry.listener; 016 017import java.util.Collection; 018import java.util.Collections; 019import java.util.HashMap; 020import java.util.Map; 021 022import org.apache.hivemind.ApplicationRuntimeException; 023import org.apache.hivemind.util.Defense; 024import org.apache.tapestry.IActionListener; 025 026/** 027 * @author Howard M. Lewis Ship 028 * @since 4.0 029 */ 030public class ListenerMapImpl implements ListenerMap 031{ 032 private final Object _target; 033 034 /** 035 * Keyed on String method name, value is 036 * {@link org.apache.tapestry.listener.ListenerMethodInvoker}. 037 */ 038 039 private final Map _invokers; 040 041 private final Map _listeners = new HashMap(); 042 043 public ListenerMapImpl(Object target, Map invokers) 044 { 045 Defense.notNull(target, "target"); 046 Defense.notNull(invokers, "invokers"); 047 048 _target = target; 049 _invokers = invokers; 050 } 051 052 public boolean canProvideListener(String name) 053 { 054 return _invokers.containsKey(name); 055 } 056 057 public synchronized IActionListener getListener(String name) 058 { 059 IActionListener result = (IActionListener) _listeners.get(name); 060 061 if (result == null) 062 { 063 result = createListener(name); 064 _listeners.put(name, result); 065 } 066 067 return result; 068 } 069 070 private IActionListener createListener(String name) 071 { 072 ListenerMethodInvoker invoker = (ListenerMethodInvoker) _invokers.get(name); 073 074 if (invoker == null) 075 throw new ApplicationRuntimeException(ListenerMessages.objectMissingMethod( 076 _target, 077 name), _target, null, null); 078 079 return new SyntheticListener(_target, invoker); 080 } 081 082 public Collection getListenerNames() 083 { 084 return Collections.unmodifiableCollection(_invokers.keySet()); 085 } 086}