001// Copyright 2004, 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.services.impl; 016 017import java.util.HashMap; 018import java.util.Map; 019 020import org.apache.hivemind.ErrorLog; 021import org.apache.hivemind.Location; 022import org.apache.hivemind.internal.Module; 023import org.apache.hivemind.service.ObjectProvider; 024import org.apache.hivemind.util.PropertyUtils; 025import org.apache.tapestry.services.Infrastructure; 026 027/** 028 * An ObjectProvider that streamlines access to the central 029 * {@link org.apache.tapestry.services.Infrastructure}object. The locator for this provider is the 030 * name of a property of the Infrastructure. 031 * 032 * @author Howard Lewis Ship 033 * @since 4.0 034 */ 035 036public class InfrastructureObjectProvider implements ObjectProvider 037{ 038 private ErrorLog _errorLog; 039 040 private Infrastructure _infrastructure; 041 042 private Map _cache = new HashMap(); 043 044 public synchronized Object provideObject(Module contributingModule, Class propertyType, 045 String locator, Location location) 046 { 047 Object result = _cache.get(locator); 048 049 if (result == null) 050 { 051 result = readProperty(locator, location); 052 _cache.put(locator, result); 053 } 054 055 return result; 056 } 057 058 Object readProperty(String locator, Location location) 059 { 060 try 061 { 062 if (PropertyUtils.isReadable(_infrastructure, locator)) 063 return PropertyUtils.read(_infrastructure, locator); 064 065 return _infrastructure.getProperty(locator); 066 } 067 catch (Throwable ex) 068 { 069 _errorLog.error(ImplMessages.unableToReadInfrastructureProperty( 070 locator, 071 _infrastructure, 072 ex), location, ex); 073 074 return null; 075 } 076 } 077 078 public void setErrorLog(ErrorLog errorLog) 079 { 080 _errorLog = errorLog; 081 } 082 083 public void setInfrastructure(Infrastructure infrastructure) 084 { 085 _infrastructure = infrastructure; 086 } 087 088}