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.support;
018    
019    import java.io.InputStream;
020    
021    import org.apache.camel.CamelContext;
022    import org.apache.camel.CamelContextAware;
023    import org.apache.camel.ExpressionIllegalSyntaxException;
024    import org.apache.camel.IsSingleton;
025    import org.apache.camel.spi.Language;
026    import org.apache.camel.util.IOHelper;
027    import org.apache.camel.util.ResourceHelper;
028    
029    /**
030     * Base language for {@link Language} implementations.
031     */
032    public abstract class LanguageSupport implements Language, IsSingleton, CamelContextAware {
033    
034        public static final String RESOURCE = "resource:";
035    
036        private CamelContext camelContext;
037    
038        public CamelContext getCamelContext() {
039            return camelContext;
040        }
041    
042        public void setCamelContext(CamelContext camelContext) {
043            this.camelContext = camelContext;
044        }
045    
046        @Override
047        public boolean isSingleton() {
048            return true;
049        }
050    
051        /**
052         * Loads the resource if the given expression is referring to an external resource by using
053         * the syntax <tt>resource:scheme:uri<tt>.
054         * If the expression is not referring to a resource, then its returned as is.
055         * <p/>
056         * For example <tt>resource:classpath:mygroovy.groovy</tt> to refer to a groovy script on the classpath.
057         *
058         * @param expression the expression
059         * @return the expression
060         * @throws ExpressionIllegalSyntaxException is thrown if error loading the resource
061         */
062        protected String loadResource(String expression) throws ExpressionIllegalSyntaxException {
063            if (camelContext != null && expression.startsWith(RESOURCE)) {
064                String uri = expression.substring(RESOURCE.length());
065                InputStream is = null;
066                try {
067                    is = ResourceHelper.resolveMandatoryResourceAsInputStream(camelContext.getClassResolver(), uri);
068                    expression = camelContext.getTypeConverter().mandatoryConvertTo(String.class, is);
069                } catch (Exception e) {
070                    throw new ExpressionIllegalSyntaxException(expression, e);
071                } finally {
072                    IOHelper.close(is);
073                }
074            }
075            return expression;
076        }
077    }