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.bean;
018
019import org.apache.camel.Expression;
020import org.apache.camel.IsSingleton;
021import org.apache.camel.Predicate;
022import org.apache.camel.spi.Language;
023import org.apache.camel.util.ExpressionToPredicateAdapter;
024import org.apache.camel.util.ObjectHelper;
025
026/**
027 * A <a href="http://camel.apache.org/bean-language.html">bean language</a>
028 * which uses a simple text notation to invoke methods on beans to evaluate predicates or expressions
029 * <p/>
030 * The notation is essentially <code>beanName.methodName</code> which is then invoked using the
031 * beanName to lookup in the <a href="http://camel.apache.org/registry.html>registry</a>
032 * then the method is invoked to evaluate the expression using the
033 * <a href="http://camel.apache.org/bean-integration.html">bean integration</a> to bind the
034 * {@link org.apache.camel.Exchange} to the method arguments.
035 * <p/>
036 * As of Camel 1.5 the bean language also supports invoking a provided bean by
037 * its classname or the bean itself.
038 *
039 * @version 
040 */
041public class BeanLanguage implements Language, IsSingleton {
042
043    /**
044     * Creates the expression based on the string syntax.
045     *
046     * @param expression the string syntax <tt>beanRef.methodName</tt> where methodName can be omitted
047     * @return the expression
048     */
049    public static Expression bean(String expression) {
050        BeanLanguage language = new BeanLanguage();
051        return language.createExpression(expression);
052    }
053
054    /**
055     * Creates the expression for invoking the bean type.
056     *
057     * @param beanType  the bean type to invoke
058     * @param method optional name of method to invoke for instance to avoid ambiguity
059     * @return the expression
060     */
061    public static Expression bean(Class<?> beanType, String method) {
062        Object bean = ObjectHelper.newInstance(beanType);
063        return bean(bean, method);
064    }
065
066    /**
067     * Creates the expression for invoking the bean type.
068     *
069     * @param bean  the bean to invoke
070     * @param method optional name of method to invoke for instance to avoid ambiguity
071     * @return the expression
072     */
073    public static Expression bean(Object bean, String method) {
074        BeanLanguage language = new BeanLanguage();
075        return language.createExpression(bean, method);
076    }
077
078    public Predicate createPredicate(String expression) {
079        return ExpressionToPredicateAdapter.toPredicate(createExpression(expression));
080    }
081
082    public Expression createExpression(String expression) {
083        ObjectHelper.notNull(expression, "expression");
084
085        String beanName = expression;
086        String method = null;
087
088        // we support both the .method name and the ?method= syntax
089        // as the ?method= syntax is very common for the bean component
090        if (expression.contains("?method=")) {
091            beanName = ObjectHelper.before(expression, "?");
092            method = ObjectHelper.after(expression, "?method=");
093        } else {
094            int idx = expression.indexOf('.');
095            if (idx > 0) {
096                beanName = expression.substring(0, idx);
097                method = expression.substring(idx + 1);
098            }
099        }
100
101        return new BeanExpression(beanName, method);
102    }
103
104    public Expression createExpression(Object bean, String method) {
105        ObjectHelper.notNull(bean, "bean");
106        return new BeanExpression(bean, method);
107    }
108
109    public boolean isSingleton() {
110        return true;
111    }
112}