io.marto.aem.utils.freemarker.FreemarkerTemplateFactory.java Source code

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Here is the source code for io.marto.aem.utils.freemarker.FreemarkerTemplateFactory.java

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/*
Copyright (c) 2015-2016 "Martin Petrovsky"
    
This file is part of aem-utils (marto.io).
    
This 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 3 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, see <http://www.gnu.org/licenses/>.
*/
package io.marto.aem.utils.freemarker;

import static java.lang.String.format;

import java.io.IOException;
import java.io.StringWriter;
import java.io.Writer;
import java.net.URL;

import org.apache.commons.codec.CharEncoding;
import org.osgi.framework.Bundle;

import freemarker.cache.URLTemplateLoader;
import freemarker.template.Configuration;
import freemarker.template.DefaultObjectWrapper;
import freemarker.template.Template;
import freemarker.template.TemplateException;

/**
 * A freemarker template processing factory that loads templates (stored as resources in an OSGi bundle) and renders them.
 */
public class FreemarkerTemplateFactory {

    private final Configuration config;

    /**
     * Create an instance that loads templates from an OSGi <tt>bundle</tt>.
     *
     * @param bundle  the OSGi bundle used to load all templates from
     */
    public FreemarkerTemplateFactory(final Bundle bundle) {
        this.config = new Configuration();
        config.setObjectWrapper(new DefaultObjectWrapper());
        config.setTemplateUpdateDelay(Integer.MAX_VALUE);
        config.setLocalizedLookup(false);
        config.setTemplateLoader(new URLTemplateLoader() {
            @Override
            protected URL getURL(String url) {
                return bundle.getEntry(url);
            }
        });
    }

    /**
     * Clear the template cache
     */
    public void clear() {
        this.config.clearTemplateCache();
        this.config.clearEncodingMap();
        this.config.clearSharedVariables();
    }

    /**
     * @param templatePath  the template to render (view)
     * @param model         the model
     * @param writer        the writer
     * @throws TemplateException  on template error
     * @throws IOException        on any other write error
     */
    public void render(String templatePath, Object model, Writer writer) throws TemplateException, IOException {
        final Template template;
        try {
            template = config.getTemplate(templatePath, CharEncoding.UTF_8);
        } catch (IOException e) {
            throw new TemplateException(format("Failed to render template '%s'", templatePath), e, null);
        }
        template.process(model, writer);
    }

    /**
     * Same as {@link #render(String, Object, Writer)} but instead returns a StringBuffer of the rendered result instead of writing it to a writer.
     *
     * @param templatePath  the template to render (view)
     * @param model         the model
     * @return a StringBuffer that contains the rendered template.
     *
     * @throws TemplateException  on template error
     * @throws IOException        on any other write error
     */
    public StringBuffer renderToStringBuffer(String templatePath, Object model)
            throws TemplateException, IOException {
        final StringWriter writer = new StringWriter();
        render(templatePath, model, writer);
        return writer.getBuffer();
    }

}