StaticFilter.java

/*******************************************************************************
 *   Gisgraphy Project 
 * 
 *   This library is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU Lesser General Public
 *   License as published by the Free Software Foundation; either
 *   version 2.1 of the License, or (at your option) any later version.
 * 
 *   This library is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 *   Lesser General Public License for more details.
 * 
 *   You should have received a copy of the GNU Lesser General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA
 * 
 *  Copyright 2008  Gisgraphy project 
 *  David Masclet <davidmasclet@gisgraphy.com>
 *  
 *  
 *******************************************************************************/
package com.gisgraphy.webapp.filter;

import java.io.IOException;
import java.util.Iterator;
import java.util.Set;

import javax.servlet.FilterChain;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.lang.StringUtils;
import org.springframework.util.PatternMatchUtils;
import org.springframework.web.filter.OncePerRequestFilter;
import org.springframework.web.util.UrlPathHelper;

/**
 * A simple filter that allows the application to continue using the .html
 * prefix for actions but also allows static files to be served up with the same
 * extension. Dojo to serve up its HTML template code. The filter works on an
 * include/exclude basis where all requests for active pages are redirected by
 * the filter to thee dispatch servlet. All Dojo related .html requests are
 * allowed to pass straight through to be processed by the servlet container as
 * per normal.
 */
public class StaticFilter extends OncePerRequestFilter {
    private final static String DEFAULT_INCLUDES = "*.html";

    private final static String DEFAULT_EXCLUDES = "";

    private static final String INCLUDES_PARAMETER = "includes";

    private static final String EXCLUDES_PARAMETER = "excludes";

    private static final String SERVLETNAME_PARAMETER = "servletName";

    private String[] excludes;

    private String[] includes;

    private String servletName = null;

    /**
     * Read the includes/excludes paramters and set the filter accordingly.
     */
    @Override
    public void initFilterBean() {
	String includesParam = getFilterConfig().getInitParameter(
		INCLUDES_PARAMETER);
	if (StringUtils.isEmpty(includesParam)) {
	    includes = parsePatterns(DEFAULT_INCLUDES);
	} else {
	    includes = parsePatterns(includesParam);
	}

	String excludesParam = getFilterConfig().getInitParameter(
		EXCLUDES_PARAMETER);
	if (StringUtils.isEmpty(excludesParam)) {
	    excludes = parsePatterns(DEFAULT_EXCLUDES);
	} else {
	    excludes = parsePatterns(excludesParam);
	}
	// if servletName is specified, set it
	servletName = getFilterConfig().getInitParameter(SERVLETNAME_PARAMETER);
    }

    @SuppressWarnings("unchecked")
    private String[] parsePatterns(String delimitedPatterns) {
	// make sure no patterns are repeated.
	Set<String> patternSet = org.springframework.util.StringUtils
		.commaDelimitedListToSet(delimitedPatterns);
	String[] patterns = new String[patternSet.size()];
	int i = 0;
	for (Iterator<String> iterator = patternSet.iterator(); iterator
		.hasNext(); i++) {
	    // no trailing/leading white space.
	    String pattern = (String) iterator.next();
	    patterns[i] = pattern.trim();
	}
	return patterns;
    }

    /**
     * This method checks to see if the current path matches includes or
     * excludes. If it matches includes and not excludes, it forwards to the
     * static resource and ends the filter chain. Otherwise, it forwards to the
     * next filter in the chain.
     * 
     * @param request
     *                the current request
     * @param response
     *                the current response
     * @param chain
     *                the filter chain
     * @throws ServletException
     *                 when something goes wrong
     * @throws IOException
     *                 when something goes terribly wrong
     */
    @Override
    public void doFilterInternal(HttpServletRequest request,
	    HttpServletResponse response, FilterChain chain)
	    throws IOException, ServletException {

	UrlPathHelper urlPathHelper = new UrlPathHelper();
	String path = urlPathHelper.getPathWithinApplication(request);
	boolean pathExcluded = PatternMatchUtils.simpleMatch(excludes, path);
	boolean pathIncluded = PatternMatchUtils.simpleMatch(includes, path);

	if (pathIncluded && !pathExcluded) {
	    if (logger.isDebugEnabled()) {
		logger.debug("Forwarding to static resource: " + path);
	    }

	    if (path.contains(".html")) {
		response.setContentType("text/html");
	    }

	    RequestDispatcher rd = getServletContext().getRequestDispatcher(
		    path);
	    rd.include(request, response);
	    return;
	}

	if (servletName != null) {
	    RequestDispatcher rd = getServletContext().getNamedDispatcher(
		    servletName);
	    rd.forward(request, response);
	    return;
	}

	chain.doFilter(request, response);
    }
}