examples/app_example2/Example2.java

/*
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. 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.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Velocity", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED 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 APACHE SOFTWARE FOUNDATION OR
 * ITS 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

import java.io.StringWriter;
import java.util.Properties;
import org.apache.velocity.app.Velocity;
import org.apache.velocity.VelocityContext;

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

/**
 * This class is a simple demonstration of how the Velocity Template Engine
 * can be used in a standalone application using the Velocity utility class.
 *
 * It demonstrates two of the 'helper' methods found in the org.apache.velocity.util.Velocity
 * class, mergeTemplate() and evaluate().
 *
 *
 * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
 * @version $Id: Example2.java,v 1.3 2001/03/20 18:03:10 geirm Exp $
 */

public class Example2
{
    public static void main( String args[] )
    {
        /* first, we init the runtime engine.  Defaults are fine. */
        
        try
        {
            Velocity.init();
        }
        catch(Exception e)
        {
            System.out.println("Problem initializing Velocity : " + e );
            return;
        }

        /* lets make a Context and put data into it */

        VelocityContext context = new VelocityContext();

        context.put("name", "Velocity");
        context.put("project", "Jakarta");
        
        /* lets render a template */

        StringWriter w = new StringWriter();

        try
        {
            Velocity.mergeTemplate("example2.vm", context, w );
        }
        catch (Exception e )
        {
            System.out.println("Problem merging template : " + e );
        }

        System.out.println(" template : " + w );

        /* 
         *  lets dynamically 'create' our template
         *  and use the evaluate() method to render it
         */

        String s = "We are using $project $name to render this.";
        w = new StringWriter();

        try
        {
            Velocity.evaluate( context, w, "mystring", s );
        }
        catch( ParseErrorException pee )
        {
            /*
             * thrown if something is wrong with the
             * syntax of our template string
             */
            System.out.println("ParseErrorException : " + pee );
        }
        catch( MethodInvocationException mee )
        {
            /*
             *  thrown if a method of a reference
             *  called by the template
             *  throws an exception. That won't happen here
             *  as we aren't calling any methods in this
             *  example, but we have to catch them anyway
             */
            System.out.println("MethodInvocationException : " + mee );
        }
        catch( Exception e )
        {
            System.out.println("Exception : " + e );
        }

        System.out.println(" string : " + w );
    }
}