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: 46968 $ 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 }