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.language.spel; 018 019 import org.apache.camel.Exchange; 020 import org.apache.camel.ExpressionEvaluationException; 021 import org.apache.camel.impl.ExpressionSupport; 022 import org.apache.camel.spring.SpringCamelContext; 023 import org.springframework.context.ApplicationContext; 024 import org.springframework.context.expression.BeanFactoryResolver; 025 import org.springframework.expression.EvaluationContext; 026 import org.springframework.expression.Expression; 027 import org.springframework.expression.ParserContext; 028 import org.springframework.expression.common.TemplateParserContext; 029 import org.springframework.expression.spel.standard.SpelExpressionParser; 030 import org.springframework.expression.spel.support.StandardEvaluationContext; 031 032 /** 033 * Class responsible for evaluating <a href="http://static.springsource.org 034 * /spring/docs/current/spring-framework-reference/html/expressions.html"> 035 * Spring Expression Language</a> in the context of Camel. 036 */ 037 @SuppressWarnings("deprecation") 038 public class SpelExpression extends ExpressionSupport { 039 040 private final String expressionString; 041 private final Class<?> type; 042 043 // SpelExpressionParser is thread-safe according to the docs 044 private final SpelExpressionParser expressionParser; 045 046 public SpelExpression(String expressionString, Class<?> type) { 047 this.expressionString = expressionString; 048 this.type = type; 049 this.expressionParser = new SpelExpressionParser(); 050 } 051 052 public static SpelExpression spel(String expression) { 053 return new SpelExpression(expression, Object.class); 054 } 055 056 public <T> T evaluate(Exchange exchange, Class<T> tClass) { 057 try { 058 Expression expression = parseExpression(); 059 EvaluationContext evaluationContext = createEvaluationContext(exchange); 060 Object value = expression.getValue(evaluationContext); 061 // Let Camel handle the type conversion 062 return exchange.getContext().getTypeConverter().convertTo(tClass, value); 063 } catch (Exception e) { 064 throw new ExpressionEvaluationException(this, exchange, e); 065 } 066 } 067 068 private EvaluationContext createEvaluationContext(Exchange exchange) { 069 StandardEvaluationContext evaluationContext = new StandardEvaluationContext(new RootObject(exchange)); 070 if (exchange.getContext() instanceof SpringCamelContext) { 071 // Support references (like @foo) in expressions to beans defined in the Registry/ApplicationContext 072 ApplicationContext applicationContext = ((SpringCamelContext) exchange.getContext()).getApplicationContext(); 073 evaluationContext.setBeanResolver(new BeanFactoryResolver(applicationContext)); 074 } 075 return evaluationContext; 076 } 077 078 private Expression parseExpression() { 079 // Support template parsing with #{ } delimiters 080 ParserContext parserContext = new TemplateParserContext(); 081 Expression expression = expressionParser.parseExpression(expressionString, parserContext); 082 return expression; 083 } 084 085 public Class<?> getType() { 086 return type; 087 } 088 089 protected String assertionFailureMessage(Exchange exchange) { 090 return expressionString; 091 } 092 093 @Override 094 public String toString() { 095 return "SpelExpression[" + expressionString + "]"; 096 } 097 }