1 package org.codehaus.plexus.interpolation; 2 3 /* 4 * Copyright 2001-2008 Codehaus Foundation. 5 * 6 * Licensed under the Apache License, Version 2.0 (the "License"); 7 * you may not use this file except in compliance with the License. 8 * You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 19 import java.util.Properties; 20 21 /** 22 * {@link ValueSource} implementation that wraps a {@link Properties} instance, 23 * and does a simple lookup of the entire expression string as the parameter for 24 * {@link Properties#getProperty(String)}, returning the result as the resolved 25 * value. 26 * 27 * @author jdcasey 28 */ 29 public class PropertiesBasedValueSource extends AbstractValueSource { 30 31 private final Properties properties; 32 33 /** 34 * Wrap the specified {@link Properties} object for use as a value source. 35 * Nulls are allowed. 36 * 37 * @param properties The properties instance to wrap. 38 */ 39 public PropertiesBasedValueSource(Properties properties) { 40 super(false); 41 this.properties = properties; 42 } 43 44 /** 45 * @return the result of {@link Properties#getProperty(String)}, using the 46 * entire expression as the key to lookup. If the wrapped properties instance 47 * is null, simply return null. 48 */ 49 public Object getValue(String expression) { 50 return properties == null ? null : properties.getProperty(expression); 51 } 52 }