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.util; 016 017import org.apache.tapestry.engine.IPropertySource; 018 019/** 020 * Obtain properties from JVM system properties. 021 * 022 * 023 * @author Howard Lewis Ship 024 * @since 2.3 025 * 026 **/ 027 028public class SystemPropertiesPropertySource implements IPropertySource 029{ 030 private static IPropertySource _shared; 031 032 public static synchronized IPropertySource getInstance() 033 { 034 if (_shared == null) 035 _shared = new SystemPropertiesPropertySource(); 036 037 return _shared; 038 } 039 040 /** 041 * Delegates to {@link System#getProperty(java.lang.String)}. 042 * 043 **/ 044 045 public String getPropertyValue(String propertyName) 046 { 047 return System.getProperty(propertyName); 048 } 049 050}