| // Copyright 2004 The Apache Software Foundation |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| package org.apache.tapestry.util; |
| |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| import org.apache.tapestry.engine.IPropertySource; |
| |
| /** |
| * An implementation of {@link IPropertySource} |
| * that delegates to a list of other implementations. This makes |
| * it possible to create a search path for property values. |
| * |
| * @author Howard Lewis Ship |
| * @version $Id$ |
| * @since 2.3 |
| * |
| **/ |
| |
| public class DelegatingPropertySource implements IPropertySource |
| { |
| private List _sources = new ArrayList(); |
| |
| public DelegatingPropertySource() |
| { |
| } |
| |
| public DelegatingPropertySource(IPropertySource delegate) |
| { |
| addSource(delegate); |
| } |
| |
| /** |
| * Adds another source to the list of delegate property sources. |
| * This is typically only done during initialization |
| * of this DelegatingPropertySource. |
| * |
| **/ |
| |
| public void addSource(IPropertySource source) |
| { |
| _sources.add(source); |
| } |
| |
| /** |
| * Re-invokes the method on each delegate property source, |
| * in order, return the first non-null value found. |
| * |
| **/ |
| |
| public String getPropertyValue(String propertyName) |
| { |
| String result = null; |
| int count = _sources.size(); |
| |
| for (int i = 0; i < count; i++) |
| { |
| IPropertySource source = (IPropertySource)_sources.get(i); |
| |
| result = source.getPropertyValue(propertyName); |
| |
| if (result != null) |
| break; |
| } |
| |
| return result; |
| } |
| |
| } |