examples/app_example1/Example.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.    
 */

import org.apache.velocity.app.Velocity;
import org.apache.velocity.VelocityContext;
import org.apache.velocity.Template;

import org.apache.velocity.exception.ParseErrorException;
import org.apache.velocity.exception.ResourceNotFoundException;

import java.io.*;
import java.util.ArrayList;

/**
 * This class is a simple demonstration of how the Velocity Template Engine
 * can be used in a standalone application.
 *
 * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
 * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
 * @version $Id$
 */

public class Example
{
    public Example(String templateFile)
    {
        try
        {
            /*
             * setup
             */

            Velocity.init("velocity.properties");

            /*
             *  Make a context object and populate with the data.  This
             *  is where the Velocity engine gets the data to resolve the
             *  references (ex. $list) in the template
             */

            VelocityContext context = new VelocityContext();
            context.put("list", getNames());

            /*
             *  get the Template object.  This is the parsed version of your
             *  template input file.  Note that getTemplate() can throw
             *   ResourceNotFoundException : if it doesn't find the template
             *   ParseErrorException : if there is something wrong with the VTL
             *   Exception : if something else goes wrong (this is generally
             *        indicative of as serious problem...)
             */

            Template template =  null;

            try
            {
                template = Velocity.getTemplate(templateFile);
            }
            catch( ResourceNotFoundException rnfe )
            {
                System.out.println("Example : error : cannot find template " + templateFile );
            }
            catch( ParseErrorException pee )
            {
                System.out.println("Example : Syntax error in template " + templateFile + ":" + pee );
            }

            /*
             *  Now have the template engine process your template using the
             *  data placed into the context.  Think of it as a  'merge'
             *  of the template and the data to produce the output stream.
             */

            BufferedWriter writer = writer = new BufferedWriter(
                new OutputStreamWriter(System.out));

            if ( template != null)
                template.merge(context, writer);

            /*
             *  flush and cleanup
             */

            writer.flush();
            writer.close();
        }
        catch( Exception e )
        {
            System.out.println(e);
        }
    }

    public ArrayList getNames()
    {
        ArrayList list = new ArrayList();

        list.add("ArrayList element 1");
        list.add("ArrayList element 2");
        list.add("ArrayList element 3");
        list.add("ArrayList element 4");

        return list;
    }

    public static void main(String[] args)
    {
        Example t = new Example(args[0]);
    }
}