EsperTemplateParser.java

/*
 * OpenCredo-Esper - simplifies adopting Esper in Java applications. 
 * Copyright (C) 2010  OpenCredo Ltd.
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

package org.opencredo.esper.config.xml;

import org.springframework.beans.factory.support.AbstractBeanDefinition;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.support.ManagedSet;
import org.springframework.beans.factory.xml.AbstractBeanDefinitionParser;
import org.springframework.beans.factory.xml.ParserContext;
import org.springframework.util.StringUtils;
import org.springframework.util.xml.DomUtils;
import org.w3c.dom.Element;

/**
 * Parses out an esper-template element.
 * 
 * @author Russ Miles (russ.miles@opencredo.com)
 * 
 */
public class EsperTemplateParser extends AbstractBeanDefinitionParser {

    @Override
    protected boolean shouldGenerateId() {
        return false;
    }

    @Override
    protected boolean shouldGenerateIdAsFallback() {
        return true;
    }

    @Override
    protected AbstractBeanDefinition parseInternal(Element element, ParserContext parserContext) {

        BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(EsperNamespaceUtils.BASE_PACKAGE
                + ".spring.EsperTemplateBean");

        initialiseStatements(element, parserContext, builder);

        initializeConfiguration(element, builder);

        initializeUnmatchedListener(element, builder);

        return builder.getBeanDefinition();
    }

    private void initializeUnmatchedListener(Element element, BeanDefinitionBuilder builder) {
        String unmatchedListenerRef = (String) element.getAttribute(EsperNamespaceUtils.UNMATCHED_LISTENER_ATTRIBUTE);

        if (StringUtils.hasText(unmatchedListenerRef)) {
            builder.addPropertyReference("unmatchedListener", unmatchedListenerRef);
        }
    }

    private void initializeConfiguration(Element element, BeanDefinitionBuilder builder) {
        String configuration = (String) element.getAttribute(EsperNamespaceUtils.CONFIGURATION_ATTRIBUTE);

        if (StringUtils.hasText(configuration)) {
            builder.addPropertyValue("configuration", configuration);
        }
    }

    private void initialiseStatements(Element element, ParserContext parserContext, BeanDefinitionBuilder builder) {
        ManagedSet statements = null;

        Element statementsElement = DomUtils.getChildElementByTagName(element, "statements");
        if (statementsElement != null) {
            EsperStatementParser statementParser = new EsperStatementParser();
            statements = statementParser.parseStatements(statementsElement, parserContext);
        }

        if (statements != null) {
            builder.addPropertyValue("statements", statements);
        }
    }
}