/*
 * Copyright 2002-2008 the original author or authors.
 *
 * 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.springframework.config.java.valuesource;

import java.util.Properties;


/**
 * Resolves values from a {@link Properties} object.
 * TODO: JAVADOC - explain relationship to env variables
 *
 * @author  Rod Johnson
 * @author  Chris Beams
 */
public class PropertiesValueResolver extends AbstractStringBasedValueResolver {

    private Properties properties;

    /**
     * Creates a new {@link PropertiesValueResolver} object.
     */
    public PropertiesValueResolver(Properties properties) {
        this.properties = properties;
    }

    /**
     * Resolves <var>name</var> against the supplied Properties object.
     * @throws ValueResolutionException if <var>name</var> does not exist
     * as a key in the supplied Properties object
     */
    @Override
    public String getString(String name) throws ValueResolutionException {
        String value = properties.getProperty(name);

        if (value == null)
            throw new ValueResolutionException(name, "No definition in properties file");

        return value;
    }

}
