001 /**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.camel.util;
018
019 import org.apache.camel.Exchange;
020 import org.apache.camel.Expression;
021
022 /**
023 * A collection of helper methods for working with expressions.
024 *
025 * @version $Revision: 687515 $
026 */
027 public final class ExpressionHelper {
028
029 /**
030 * Utility classes should not have a public constructor.
031 */
032 private ExpressionHelper() {
033 }
034
035 /**
036 * Evaluates the given expression on the exchange as a String value
037 *
038 * @param expression the expression to evaluate
039 * @param exchange the exchange to use to evaluate the expression
040 * @return the result of the evaluation as a string.
041 */
042 public static <E extends Exchange> String evaluateAsString(Expression<E> expression, E exchange) {
043 return evaluateAsType(expression, exchange, String.class);
044 }
045
046 /**
047 * Evaluates the given expression on the exchange, converting the result to
048 * the given type
049 *
050 * @param expression the expression to evaluate
051 * @param exchange the exchange to use to evaluate the expression
052 * @param resultType the type of the result that is required
053 * @return the result of the evaluation as the specified type.
054 */
055 public static <T, E extends Exchange> T evaluateAsType(Expression<E> expression, E exchange,
056 Class<T> resultType) {
057 Object value = expression.evaluate(exchange);
058 return exchange.getContext().getTypeConverter().convertTo(resultType, exchange, value);
059 }
060 }