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 */ 017package org.apache.camel.language.spel; 018 019import org.apache.camel.Exchange; 020import org.apache.camel.ExpressionEvaluationException; 021import org.apache.camel.impl.ExpressionSupport; 022import org.apache.camel.spring.SpringCamelContext; 023import org.apache.camel.spring.util.RegistryBeanResolver; 024import org.springframework.context.ApplicationContext; 025import org.springframework.context.expression.BeanFactoryResolver; 026import org.springframework.expression.BeanResolver; 027import org.springframework.expression.EvaluationContext; 028import org.springframework.expression.Expression; 029import org.springframework.expression.ParserContext; 030import org.springframework.expression.common.TemplateParserContext; 031import org.springframework.expression.spel.standard.SpelExpressionParser; 032import org.springframework.expression.spel.support.StandardEvaluationContext; 033 034/** 035 * Class responsible for evaluating <a href="https://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#expressions"> 036 * Spring Expression Language (SpEL)</a> in the context of Camel. 037 */ 038@SuppressWarnings("deprecation") 039public class SpelExpression extends ExpressionSupport { 040 041 private final String expressionString; 042 private final Class<?> type; 043 private final BeanResolver beanResolver; 044 045 // SpelExpressionParser is thread-safe according to the docs 046 private final SpelExpressionParser expressionParser; 047 048 public SpelExpression(String expressionString, Class<?> type) { 049 this(expressionString, type, null); 050 } 051 052 public SpelExpression(String expressionString, Class<?> type, BeanResolver beanResolver) { 053 this.expressionString = expressionString; 054 this.type = type; 055 this.beanResolver = beanResolver; 056 this.expressionParser = new SpelExpressionParser(); 057 } 058 059 public static SpelExpression spel(String expression) { 060 return new SpelExpression(expression, Object.class); 061 } 062 063 public <T> T evaluate(Exchange exchange, Class<T> tClass) { 064 try { 065 Expression expression = parseExpression(); 066 EvaluationContext evaluationContext = createEvaluationContext(exchange); 067 Object value = expression.getValue(evaluationContext); 068 // Let Camel handle the type conversion 069 return exchange.getContext().getTypeConverter().convertTo(tClass, value); 070 } catch (Exception e) { 071 throw new ExpressionEvaluationException(this, exchange, e); 072 } 073 } 074 075 private EvaluationContext createEvaluationContext(Exchange exchange) { 076 StandardEvaluationContext evaluationContext = new StandardEvaluationContext(new RootObject(exchange)); 077 if (beanResolver != null) { 078 evaluationContext.setBeanResolver(beanResolver); 079 } else if (exchange.getContext() instanceof SpringCamelContext) { 080 // Support references (like @foo) in expressions to beans defined in the Registry/ApplicationContext 081 ApplicationContext applicationContext = ((SpringCamelContext) exchange.getContext()).getApplicationContext(); 082 evaluationContext.setBeanResolver(new BeanFactoryResolver(applicationContext)); 083 } else { 084 evaluationContext.setBeanResolver(new RegistryBeanResolver(exchange.getContext().getRegistry())); 085 } 086 return evaluationContext; 087 } 088 089 private Expression parseExpression() { 090 // Support template parsing with #{ } delimiters 091 ParserContext parserContext = new TemplateParserContext(); 092 Expression expression = expressionParser.parseExpression(expressionString, parserContext); 093 return expression; 094 } 095 096 public Class<?> getType() { 097 return type; 098 } 099 100 protected String assertionFailureMessage(Exchange exchange) { 101 return expressionString; 102 } 103 104 @Override 105 public String toString() { 106 return "SpelExpression[" + expressionString + "]"; 107 } 108}