/*
* Copyright 2002-2014 the original author or authors.
*
* 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 org.springframework.web.servlet.view.groovy;
import java.io.BufferedWriter;
import java.io.IOException;
import java.util.Locale;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import groovy.text.Template;
import groovy.text.markup.MarkupTemplateEngine;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactoryUtils;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextException;
import org.springframework.web.servlet.view.AbstractTemplateView;
import org.springframework.web.util.NestedServletException;
/**
* An {@link org.springframework.web.servlet.view.AbstractTemplateView AbstractTemplateView}
* based on Groovy XML/XHTML markup templates.
*
* <p>Spring's Groovy Markup Template support requires Groovy 2.3.1 and higher.
*
* @author Brian Clozel
* @author Rossen Stoyanchev
* @since 4.1
* @see GroovyMarkupViewResolver
* @see GroovyMarkupConfigurer
* @see <a href="http://beta.groovy-lang.org/docs/groovy-2.3.2/html/documentation/markup-template-engine.html">
* Groovy Markup Template engine documentation</a>
*/
public class GroovyMarkupView extends AbstractTemplateView {
private MarkupTemplateEngine engine;
/**
* Set the MarkupTemplateEngine to use in this view.
* <p>If not set, the engine is auto-detected by looking up up a single
* {@link GroovyMarkupConfig} bean in the web application context and using
* it to obtain the configured {@code MarkupTemplateEngine} instance.
* @see GroovyMarkupConfig
*/
public void setTemplateEngine(MarkupTemplateEngine engine) {
this.engine = engine;
}
@Override
public boolean checkResource(Locale locale) throws Exception {
try {
this.engine.resolveTemplate(getUrl());
}
catch (IOException exception) {
return false;
}
return true;
}
/**
* Invoked at startup.
* If no {@link #setTemplateEngine(MarkupTemplateEngine) templateEngine} has
* been manually set, this method looks up a {@link GroovyMarkupConfig} bean
* by type and uses it to obtain the Groovy Markup template engine.
* @see GroovyMarkupConfig
* @see #setTemplateEngine(groovy.text.markup.MarkupTemplateEngine)
*/
@Override
protected void initApplicationContext(ApplicationContext context) {
super.initApplicationContext();
if (this.engine == null) {
setTemplateEngine(autodetectMarkupTemplateEngine());
}
}
/**
* Autodetect a MarkupTemplateEngine via the ApplicationContext.
* Called if a MarkupTemplateEngine has not been manually configured.
*/
protected MarkupTemplateEngine autodetectMarkupTemplateEngine() throws BeansException {
try {
return BeanFactoryUtils.beanOfTypeIncludingAncestors(getApplicationContext(),
GroovyMarkupConfig.class, true, false).getTemplateEngine();
}
catch (NoSuchBeanDefinitionException ex) {
throw new ApplicationContextException("Expected a single GroovyMarkupConfig bean in the current " +
"Servlet web application context or the parent root context: GroovyMarkupConfigurer is " +
"the usual implementation. This bean may have any name.", ex);
}
}
@Override
protected void renderMergedTemplateModel(Map<String, Object> model,
HttpServletRequest request, HttpServletResponse response) throws Exception {
Template template = getTemplate(getUrl());
template.make(model).writeTo(new BufferedWriter(response.getWriter()));
}
/**
* Return a template compiled by the configured Groovy Markup template engine
* for the given view URL.
*/
protected Template getTemplate(String viewUrl) throws Exception {
try {
return this.engine.createTemplateByPath(viewUrl);
}
catch (ClassNotFoundException ex) {
Throwable cause = (ex.getCause() != null ? ex.getCause() : ex);
throw new NestedServletException("Could not find class while rendering Groovy Markup view with name '" +
getUrl() + "': " + ex.getMessage() + "'", cause);
}
}
}