org.apache.struts2.components.template.FreemarkerTemplateEngine Maven / Gradle / Ivy
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* 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 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 freemarker.core.ParseException;
import freemarker.template.Configuration;
import freemarker.template.SimpleHash;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.struts2.ServletActionContext;
import org.apache.struts2.views.freemarker.FreemarkerManager;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.Writer;
import java.util.List;
import java.util.Map;
/**
* 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 = LogManager.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 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;
}
}
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";
}
}