// Copyright Mar 18, 2006 The Apache Software Foundation
//
// 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.apache.tapestry.services.impl;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
import org.apache.tapestry.IComponent;
import org.apache.tapestry.IJSONRender;
import org.apache.tapestry.IMarkupWriter;
import org.apache.tapestry.IPage;
import org.apache.tapestry.IRender;
import org.apache.tapestry.IRequestCycle;
import org.apache.tapestry.engine.NullWriter;
import org.apache.tapestry.json.IJSONWriter;
import org.apache.tapestry.markup.MarkupWriterSource;
import org.apache.tapestry.services.RequestLocaleManager;
import org.apache.tapestry.services.ResponseBuilder;
import org.apache.tapestry.services.ServiceConstants;
import org.apache.tapestry.util.ContentType;
import org.apache.tapestry.web.WebResponse;
/**
* Class that implements JSON responses in tapestry.
*
* @see <a href="http://json.org">json.org</a>
* @author jkuhnert
*/
public class JSONResponseBuilder implements ResponseBuilder
{
/** Writer that creates JSON output response. */
protected IJSONWriter _writer;
/** Passed in to bypass normal rendering. */
protected IMarkupWriter _nullWriter = NullWriter.getSharedInstance();
/** Parts that will be updated. */
protected List _parts = new ArrayList();
protected RequestLocaleManager _localeManager;
protected MarkupWriterSource _markupWriterSource;
protected WebResponse _webResponse;
/**
* Creates a new response builder with the required services it needs
* to render the response when {@link #renderResponse(IRequestCycle)} is called.
*
* @param localeManager
* Used to set the locale on the response.
* @param markupWriterSource
* Creates IJSONWriter instance to be used.
* @param webResponse
* Web response for output stream.
*/
public JSONResponseBuilder(RequestLocaleManager localeManager,
MarkupWriterSource markupWriterSource,
WebResponse webResponse)
{
_localeManager = localeManager;
_markupWriterSource = markupWriterSource;
_webResponse = webResponse;
}
/**
*
* {@inheritDoc}
*/
public boolean isDynamic()
{
return Boolean.TRUE;
}
/**
* {@inheritDoc}
*/
public void renderResponse(IRequestCycle cycle)
throws IOException
{
_localeManager.persistLocale();
IPage page = cycle.getPage();
ContentType contentType = page.getResponseContentType();
String encoding = contentType.getParameter(ENCODING_KEY);
if (encoding == null)
{
encoding = cycle.getEngine().getOutputEncoding();
contentType.setParameter(ENCODING_KEY, encoding);
}
PrintWriter printWriter = _webResponse.getPrintWriter(contentType);
_writer = _markupWriterSource.newJSONWriter(printWriter, contentType);
// render response
parseParameters(cycle);
cycle.renderPage(this);
_writer.close();
}
/**
* Grabs the incoming parameters needed for json responses, most notable the
* {@link ServiceConstants#UPDATE_PARTS} parameter.
*
* @param cycle
* The request cycle to parse from
*/
protected void parseParameters(IRequestCycle cycle)
{
Object[] updateParts = cycle
.getParameters(ServiceConstants.UPDATE_PARTS);
for(int i = 0; i < updateParts.length; i++)
_parts.add(updateParts[i].toString());
}
/**
* {@inheritDoc}
*/
public void render(IMarkupWriter writer, IRender render, IRequestCycle cycle)
{
if (IJSONRender.class.isInstance(render)
&& IComponent.class.isInstance(render))
{
IJSONRender json = (IJSONRender) render;
IComponent component = (IComponent) render;
if (!_parts.contains(component.getId()))
{
render.render(_nullWriter, cycle);
return;
}
json.renderComponent(_writer, cycle);
}
render.render(_nullWriter, cycle);
}
/**
* {@inheritDoc}
*/
public void updateComponent(String id)
{
if (!_parts.contains(id))
_parts.add(id);
}
/**
* {@inheritDoc}
*/
public IMarkupWriter getWriter()
{
return _nullWriter;
}
/**
* {@inheritDoc}
*/
public IMarkupWriter getWriter(String id, String type)
{
return _nullWriter;
}
/**
* {@inheritDoc}
*/
public boolean isBodyScriptAllowed(IComponent target)
{
return false;
}
/**
* {@inheritDoc}
*/
public boolean isExternalScriptAllowed(IComponent target)
{
return false;
}
/**
* {@inheritDoc}
*/
public boolean isInitializationScriptAllowed(IComponent target)
{
return false;
}
/**
* {@inheritDoc}
*/
public void beginBodyScript(IRequestCycle cycle)
{
// does nothing
}
/**
* {@inheritDoc}
*/
public void endBodyScript(IRequestCycle cycle)
{
// does nothing
}
/**
* {@inheritDoc}
*/
public void writeBodyScript(String script, IRequestCycle cycle)
{
// does nothing
}
/**
* {@inheritDoc}
*/
public void writeExternalScript(String url, IRequestCycle cycle)
{
// does nothing
}
/**
* {@inheritDoc}
*/
public void writeImageInitializations(String script, String preloadName, IRequestCycle cycle)
{
// does nothing
}
/**
* {@inheritDoc}
*/
public void writeInitializationScript(String script)
{
// does nothing
}
}