VelocityRender.java

/**
 * Copyright (c) 2011-2013, James Zhan 詹波 (jfinal@126.com).
 *
 * Licensed 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.
 */

package net.tooan.ynpay.third.jfinal.render;

import org.apache.velocity.Template;
import org.apache.velocity.VelocityContext;
import org.apache.velocity.app.Velocity;
import org.apache.velocity.exception.ParseErrorException;
import org.apache.velocity.exception.ResourceNotFoundException;

import javax.servlet.ServletContext;
import java.io.PrintWriter;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Map.Entry;
import java.util.Properties;
import java.util.Set;

/**
 * VelocityRender.
 */
public class VelocityRender extends Render {

    private static final long serialVersionUID = 1012573049421601960L;
    private transient static final String encoding = getEncoding();
    private transient static final String contentType = "text/html;charset=" + encoding;
    private transient static final Properties properties = new Properties();

    private transient static boolean notInit = true;

    public VelocityRender(String view) {
        this.view = view;
    }

	/*
    static {
		String webPath = RenderFactory.getServletContext().getRealPath("/");
		
		Properties properties = new Properties();
		properties.setProperty(Velocity.FILE_RESOURCE_LOADER_PATH, webPath);
		properties.setProperty(Velocity.ENCODING_DEFAULT, encoding); 
		properties.setProperty(Velocity.INPUT_ENCODING, encoding); 
		properties.setProperty(Velocity.OUTPUT_ENCODING, encoding); 
		
		Velocity.init(properties);	// Velocity.init("velocity.properties");	// setup
	}*/

    static void init(ServletContext servletContext) {
        String webPath = servletContext.getRealPath("/");
        properties.setProperty(Velocity.FILE_RESOURCE_LOADER_PATH, webPath);
        properties.setProperty(Velocity.ENCODING_DEFAULT, encoding);
        properties.setProperty(Velocity.INPUT_ENCODING, encoding);
        properties.setProperty(Velocity.OUTPUT_ENCODING, encoding);
    }

    public static void setProperties(Properties properties) {
        Set<Entry<Object, Object>> set = properties.entrySet();
        for (Iterator<Entry<Object, Object>> it = set.iterator(); it.hasNext(); ) {
            Entry<Object, Object> e = it.next();
            VelocityRender.properties.put(e.getKey(), e.getValue());
        }
    }

    public void render() {
        if (notInit) {
            Velocity.init(properties);    // Velocity.init("velocity.properties");	// setup
            notInit = false;
        }

        PrintWriter writer = null;
        try {
            /*
             *  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();

            // Map root = new HashMap();
            for (Enumeration<String> attrs = request.getAttributeNames(); attrs.hasMoreElements(); ) {
                String attrName = attrs.nextElement();
                context.put(attrName, request.getAttribute(attrName));
            }
    		
            /*
             *  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 = Velocity.getTemplate(view);
            
            /*
             *  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.
             */
            response.setContentType(contentType);
            writer = response.getWriter();    // BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(System.out));

            template.merge(context, writer);
            writer.flush();    // flush and cleanup
        } catch (ResourceNotFoundException e) {
            throw new RenderException("Example : error : cannot find template " + view, e);
        } catch (ParseErrorException e) {
            throw new RenderException("Example : Syntax error in template " + view + ":" + e, e);
        } catch (Exception e) {
            throw new RenderException(e);
        } finally {
            if (writer != null)
                writer.close();
        }
    }
}