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. 014 015 package org.apache.tapestry.binding; 016 017 import org.apache.hivemind.Location; 018 import org.apache.hivemind.util.Defense; 019 import org.apache.tapestry.BindingException; 020 import org.apache.tapestry.IAsset; 021 import org.apache.tapestry.IComponent; 022 import org.apache.tapestry.coerce.ValueConverter; 023 024 /** 025 * A binding that is connected to an asset provided by a component. 026 * 027 * @author Howard M. Lewis Ship 028 * @since 4.0 029 */ 030 public class AssetBinding extends AbstractBinding 031 { 032 private final IComponent _component; 033 034 private final String _assetName; 035 036 public AssetBinding(String description, ValueConverter valueConverter, Location location, 037 IComponent component, String assetName) 038 { 039 super(description, valueConverter, location); 040 041 Defense.notNull(component, "component"); 042 Defense.notNull(assetName, "assetName"); 043 044 _component = component; 045 _assetName = assetName; 046 } 047 048 public Object getObject() 049 { 050 IAsset result = _component.getAsset(_assetName); 051 052 if (result == null) 053 throw new BindingException(BindingMessages.missingAsset(_component, _assetName), 054 _component, getLocation(), this, null); 055 056 return result; 057 } 058 059 public Object getComponent() 060 { 061 return _component; 062 } 063 }