JsonpCallbackFilter.java

/*
 * Copyright: (c) 2004-2011 Mayo Foundation for Medical Education and 
 * Research (MFMER). All rights reserved. MAYO, MAYO CLINIC, and the
 * triple-shield Mayo logo are trademarks and service marks of MFMER.
 *
 * Except as contained in the copyright notice above, or as used to identify 
 * MFMER as the author of this software, the trade names, trademarks, service
 * marks, or product names of the copyright holder shall not be used in
 * advertising, promotion or otherwise in connection with this software without
 * prior written authorization of the copyright holder.
 *
 * 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 edu.mayo.cts2.framework.webapp.rest.filter.jsonp;

import java.io.IOException;
import java.io.OutputStream;
import java.util.Map;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import edu.mayo.cts2.framework.model.exception.UnspecifiedCts2Exception;

/**
 * The Class JsonpCallbackFilter.
 *
 * @author <a href="mailto:kevin.peterson@mayo.edu">Kevin Peterson</a>
 */
public class JsonpCallbackFilter implements Filter {

	private static Log log = LogFactory.getLog(JsonpCallbackFilter.class);

	/* (non-Javadoc)
	 * @see javax.servlet.Filter#init(javax.servlet.FilterConfig)
	 */
	public void init(FilterConfig fConfig) throws ServletException {}

	/* (non-Javadoc)
	 * @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain)
	 */
	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
		if(! (request instanceof HttpServletRequest)){
			throw new UnspecifiedCts2Exception("ServletRequest expected to be of type HttpServletRequest");
		}
		
		if(! (response instanceof HttpServletResponse)){
			throw new UnspecifiedCts2Exception("ServletResponse expected to be of type HttpServletResponse");
		}
		
		HttpServletRequest httpRequest = (HttpServletRequest) request;
		HttpServletResponse httpResponse = (HttpServletResponse) response;

		@SuppressWarnings("unchecked")
		Map<String, String[]> parms = httpRequest.getParameterMap();

		if(parms.containsKey("callback")) {
			if(log.isDebugEnabled()){
				log.debug("Wrapping response with JSONP callback '" + parms.get("callback")[0] + "'");
			}

			OutputStream out = httpResponse.getOutputStream();

			GenericResponseWrapper wrapper = new GenericResponseWrapper(httpResponse);

			chain.doFilter(request, wrapper);

			out.write(new String(parms.get("callback")[0] + "(").getBytes());
			out.write(wrapper.getData());
			out.write(new String(");").getBytes());

			wrapper.setContentType("text/javascript;charset=UTF-8");

			out.close();
		} else {
			chain.doFilter(request, response);
		}
	}

	/* (non-Javadoc)
	 * @see javax.servlet.Filter#destroy()
	 */
	public void destroy() {
		//
	}
}