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Struts example source code file (FreemarkerTemplateEngine.java)

This example Struts source code file (FreemarkerTemplateEngine.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

configuration, configuration, exception, freemarker, http, httpservletrequest, httpservletresponse, io, ioexception, ioexception, request, response, servlet, servletcontext, string, string, template, util, writer, writer

The Struts FreemarkerTemplateEngine.java source code

/*
 * $Id: FreemarkerTemplateEngine.java 965050 2010-07-17 10:10:46Z lukaszlenart $
 *
 * 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.components.template;

import java.io.IOException;
import java.io.Writer;
import java.util.Map;
import java.util.List;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts2.ServletActionContext;
import org.apache.struts2.views.freemarker.FreemarkerManager;

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

import freemarker.template.Configuration;
import freemarker.template.SimpleHash;
import freemarker.core.ParseException;

/**
 * Freemarker based template engine.
 */
public class FreemarkerTemplateEngine extends BaseTemplateEngine {
    static Class bodyContent = null;
    protected FreemarkerManager freemarkerManager;

    static {
        try {
            bodyContent = ClassLoaderUtil.loadClass("javax.servlet.jsp.tagext.BodyContent",
                    FreemarkerTemplateEngine.class);
        } catch (ClassNotFoundException e) {
            // this is OK -- this just means JSP isn't even being used here, which is perfectly fine.
            // we need this class in environments that use JSP to know when to wrap the writer
            // and ignore flush() calls. In JSP, it is illegal for a BodyContent writer to be flushed(),
            // so we have to take caution here.
        }
    }

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

    @Inject
    public void setFreemarkerManager(FreemarkerManager mgr) {
        this.freemarkerManager = mgr;
    }
    
    public void renderTemplate(TemplateRenderingContext templateContext) throws Exception {
    	// get the various items required from the stack
        ValueStack stack = templateContext.getStack();
        Map context = stack.getContext();
        ServletContext servletContext = (ServletContext) context.get(ServletActionContext.SERVLET_CONTEXT);
        HttpServletRequest req = (HttpServletRequest) context.get(ServletActionContext.HTTP_REQUEST);
        HttpServletResponse res = (HttpServletResponse) context.get(ServletActionContext.HTTP_RESPONSE);

        // prepare freemarker
        Configuration config = freemarkerManager.getConfiguration(servletContext);

        // get the list of templates we can use
        List<Template> templates = templateContext.getTemplate().getPossibleTemplates(this);

        // find the right template
        freemarker.template.Template template = null;
        String templateName = null;
        Exception exception = null;
        for (Template t : templates) {
            templateName = getFinalTemplateName(t);
                try {
                    // try to load, and if it works, stop at the first one
                    template = config.getTemplate(templateName);
                    break;
                } catch (ParseException e) {
                    // template was found but was invalid - always report this.
                    exception = e;
                    break;
                } catch (IOException e) {
                    // FileNotFoundException is anticipated - report the first IOException if no template found
                    if (exception == null) {
                        exception = e;
                    }
                }
        }

        if (template == null) {
            if (LOG.isErrorEnabled()) {
                LOG.error("Could not load the FreeMarker template named '" + templateContext.getTemplate().getName() +"':");
                for (Template t : templates) {
                    LOG.error("Attempted: " + getFinalTemplateName(t));
                }
                LOG.error("The TemplateLoader provided by the FreeMarker Configuration was a: "+config.getTemplateLoader().getClass().getName());
            }
            if (exception != null) {
                throw exception;
            } else {
                return;
            }
        }

        if (LOG.isDebugEnabled()) {
            LOG.debug("Rendering template " + templateName);
        }

        ActionInvocation ai = ActionContext.getContext().getActionInvocation();

        Object action = (ai == null) ? null : ai.getAction();
        SimpleHash model = freemarkerManager.buildTemplateModel(stack, action, servletContext, req, res, config.getObjectWrapper());

        model.put("tag", templateContext.getTag());
        model.put("themeProperties", getThemeProps(templateContext.getTemplate()));

        // the BodyContent JSP writer doesn't like it when FM flushes automatically --
        // so let's just not do it (it will be flushed eventually anyway)
        Writer writer = templateContext.getWriter();
        final Writer wrapped = writer;
        writer = new Writer() {
            public void write(char cbuf[], int off, int len) throws IOException {
                wrapped.write(cbuf, off, len);
            }

            public void flush() throws IOException {
                // nothing!
            }

            public void close() throws IOException {
                wrapped.close();
            }
        };

        try {
            stack.push(templateContext.getTag());
            template.process(model, writer);
        } finally {
            stack.pop();
        }
    }

    protected String getSuffix() {
        return "ftl";
    }


}

Other Struts examples (source code examples)

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