org.eclipse.krazo.ext.jsr223.Jsr223ViewEngine Maven / Gradle / Ivy
/*
* Copyright (c) 2014-2015 Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2018, 2019 Eclipse Krazo committers and contributors
*
* 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.
*
* SPDX-License-Identifier: Apache-2.0
*/
package org.eclipse.krazo.ext.jsr223;
import org.eclipse.krazo.engine.ViewEngineBase;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.nio.charset.Charset;
import javax.annotation.Priority;
import javax.enterprise.context.ApplicationScoped;
import javax.inject.Inject;
import javax.mvc.engine.ViewEngine;
import javax.mvc.engine.ViewEngineContext;
import javax.mvc.engine.ViewEngineException;
import javax.script.Bindings;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
import javax.servlet.ServletContext;
/**
* The JSR-223 ViewEngine.
*
* @author Manfred Riem ([email protected])
*/
@ApplicationScoped
@Priority(ViewEngine.PRIORITY_FRAMEWORK)
public class Jsr223ViewEngine extends ViewEngineBase {
/**
* Stores our global ScriptEngineManager.
*/
ScriptEngineManager scriptEngineManager = new ScriptEngineManager();
/**
* Servlet context so we can load load the script
*/
@Inject
private ServletContext servletContext;
/**
* What extensions does the view engine support.
*
* @param view the view.
* @return if we support the extension or not.
*/
@Override
public boolean supports(String view) {
return getScriptEngine(view) != null;
}
/**
* Get the script engine by extension.
*
* @param view the view.
* @return the script engine, or null if not found.
*/
private ScriptEngine getScriptEngine(String view) {
if (view.contains(".")) {
String extension = view.substring(view.lastIndexOf(".") + 1);
return scriptEngineManager.getEngineByExtension(extension);
}
return null;
}
/**
* Process the view.
*
* @param context the context.
* @throws ViewEngineException when the view engine experienced an error.
*/
@Override
public void processView(ViewEngineContext context) throws ViewEngineException {
ScriptEngine scriptEngine = getScriptEngine(context.getView());
Object responseObject;
try {
InputStream inputStream = servletContext.getResourceAsStream(resolveView(context));
InputStreamReader reader = new InputStreamReader(inputStream);
Bindings bindings = scriptEngine.createBindings();
bindings.put("models", context.getModels().asMap());
responseObject = scriptEngine.eval(reader, bindings);
} catch (ScriptException exception) {
throw new ViewEngineException("Unable to execute script", exception);
}
Charset charset = resolveCharsetAndSetContentType(context);
try (Writer writer = new OutputStreamWriter(context.getOutputStream(), charset)) {
writer.write(responseObject.toString());
} catch (IOException exception) {
throw new ViewEngineException("Unable to write response", exception);
}
}
}