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Struts example source code file (JavaTemplateEngine.java)

This example Struts source code file (JavaTemplateEngine.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Struts tags/keywords

class, exception, hashmap, invalid, invalid, log, override, string, string, stringtokenizer, theme, theme, themes, themes, util

The Struts JavaTemplateEngine.java source code

/*
 * $Id: JavaTemplateEngine.java 773903 2009-05-12 13:59:48Z musachy $
 *
 * 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.
 */
package org.apache.struts2.views.java;

import org.apache.struts2.StrutsException;
import org.apache.struts2.components.template.BaseTemplateEngine;
import org.apache.struts2.components.template.Template;
import org.apache.struts2.components.template.TemplateRenderingContext;
import org.apache.struts2.views.java.simple.SimpleTheme;

import java.util.HashMap;
import java.util.StringTokenizer;

import com.opensymphony.xwork2.util.logging.LoggerFactory;
import com.opensymphony.xwork2.util.logging.Logger;
import com.opensymphony.xwork2.util.ClassLoaderUtil;
import com.opensymphony.xwork2.inject.Inject;

/**
 * Template engine that renders tags using java implementations
 */
public class JavaTemplateEngine extends BaseTemplateEngine {

    private static final Logger LOG = LoggerFactory.getLogger(JavaTemplateEngine.class);

    private Themes themes = new Themes() {{
        add(new SimpleTheme());
    }};

    @Override
    protected String getSuffix() {
        return "java";
    }

    public void renderTemplate(TemplateRenderingContext templateContext)
            throws Exception {
        Template t = templateContext.getTemplate();
        Theme theme = themes.get(t.getTheme());
        if (theme == null) {
            throw new StrutsException("Cannot render tag [" + t.getName() + "] because theme [" + t.getTheme() + "] was not found.");
        }
        theme.renderTag(t.getName(), templateContext);
    }

    private class Themes {
        private HashMap<String, Theme> themes = new HashMap();

        public void add(Theme theme) {
            themes.put(theme.getName(), theme);
        }

        public Theme get(String name) {
            return themes.get(name);
        }
    }

    /**
     * Allows for providing custom theme classes (implementations of the org.apache.struts2.views.java.Theme) interface
     * for custom rendering of tags using the javatemplates engine
     *
     * @param themeClasses a comma delimited list of custom theme class names
     */
    @Inject(value = "struts.javatemplates.customThemes", required = false)
    public void setThemeClasses(String themeClasses) {

        StringTokenizer customThemes = new StringTokenizer(themeClasses, ",");

        while (customThemes.hasMoreTokens()) {
            String themeClass = customThemes.nextToken().trim();
            try {
                LOG.info("Registering custom theme '" + themeClass + "' to javatemplates engine");


                //FIXME: This means Themes must have no-arg constructor - should use object factory here
                //ObjectFactory.getObjectFactory().buildBean(ClassLoaderUtil.loadClass(themeClass, getClass()), null);
                themes.add((Theme) ClassLoaderUtil.loadClass(themeClass, getClass()).newInstance());

            } catch (ClassCastException cce) {
                LOG.error("Invalid java them class '" + themeClass + "'. Class does not implement 'org.apache.struts2.views.java.Theme' interface");
            } catch (ClassNotFoundException cnf) {
                LOG.error("Invalid java theme class '" + themeClass + "'. Class not found");
            } catch (Exception e) {
                LOG.error("Could not find messages file " + themeClass + ".properties. Skipping");
            }
        }
    }
}

Other Struts examples (source code examples)

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