// Copyright (c) 2002, John Munsch
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without 
// modification, are permitted provided that the following conditions are met:
//
//     * Redistributions of source code must retain the above copyright notice, 
//       this list of conditions and the following disclaimer.
// 
//     * Redistributions in binary form must reproduce the above copyright 
//       notice, this list of conditions and the following disclaimer in the 
//       documentation and/or other materials provided with the distribution.
// 
//     * Neither the name of the John Munsch nor the names of its contributors 
//       may be used to endorse or promote products derived from this software 
//       without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
// POSSIBILITY OF SUCH DAMAGE.
// 
// To learn more about open source licenses, please visit: 
// http://opensource.org/index.php

package com.johnmunsch.util;

import java.io.StringWriter;

import org.apache.log4j.*;
import org.apache.velocity.*;
import org.apache.velocity.app.Velocity;
import org.apache.velocity.exception.*;

/**
 * Boilerplate puts together context information and a template and produces an
 * output string that has all the replacements done in it.
 */
public class Boilerplate {
    private static Logger log = Logger.getLogger(Boilerplate.class.getName());
    
    public static String apply(VelocityContext context,
            String templateFilename) throws Exception {
        Template template = null;
        StringWriter sw = new StringWriter();

        Velocity.init();

        try {
            template = Velocity.getTemplate(templateFilename);

            template.merge(context, sw);
        } catch (ResourceNotFoundException rnfe) {
            log.error("Could not find the named template file.", rnfe);
            throw rnfe;
        } catch (ParseErrorException pee) {
            log.error("Error in the template file.", pee);
            throw pee;
        } catch (MethodInvocationException mie) {
            log.error("Error in function called by the template file.", mie);
            throw mie;
        }
       
        return sw.toString();
    }
}

import java.io.InputStream;

import javax.servlet.ServletContext;

import org.apache.commons.collections.ExtendedProperties;
import org.apache.velocity.exception.ResourceNotFoundException;
import org.apache.velocity.runtime.resource.Resource;
import org.apache.velocity.runtime.resource.loader.ResourceLoader;

public class WebAppResourceLoader extends ResourceLoader {

    private static ServletContext context = null;

    public void init(ExtendedProperties extendedProperties) {

    }

    private static ServletContext getServletContext() {
        return context;
    }

    public static void setServletContext(ServletContext context) {
        WebAppResourceLoader.context = context;
    }

    /**
     * @see org.apache.velocity.runtime.resource.loader.ResourceLoader#getResourceStream(java.lang.String)
     */
    public InputStream getResourceStream(String name)
            throws ResourceNotFoundException {
        InputStream result = null;

        if (name == null || name.length() == 0) {
            throw new ResourceNotFoundException("No template name provided");
        }

        try {
            if (!name.startsWith("/"))
                name = "/" + name;

            result = getServletContext().getResourceAsStream(name);
        } catch (NullPointerException npe) {
            throw new ResourceNotFoundException("ServletContext not found");
        } catch (Exception fnfe) {
            throw new ResourceNotFoundException(fnfe.getMessage());
        }

        return result;
    }

    public boolean isSourceModified(Resource arg0) {
        return false;
    }

    public long getLastModified(Resource arg0) {
        return 0;
    }

}

    WebAppResourceLoader.setServletContext(servletContext);
    Properties props = new Properties();
    props.setProperty("resource.loader", "webapp");
    props.setProperty("webapp.resource.loader.description", 
        "Load from the ServletContext");
    props.setProperty("webapp.resource.loader.class",
        "package.WebAppResourceLoader");
    Velocity.init(props);

#parse("/WEB-INF/something.vm")