import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;
import javax.servlet.http.HttpSession;
import java.io.IOException;
/**
* Servlet filter which disables URL-encoded session identifiers.
* <p/>
* <pre>
* Copyright (c) 2006, Craig Condit. All rights reserved.
* <p/>
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* <p/>
*   * Redistributions of source code must retain the above copyright notice,
*     this list of conditions and the following disclaimer.
*   * Redistributions in binary form must reproduce the above copyright notice,
*     this list of conditions and the following disclaimer in the documentation
*     and/or other materials provided with the distribution.
* <p/>
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
* </pre>
*/
@SuppressWarnings("deprecation")
public class DisableUrlSessionFilter implements Filter {
/**
* Filters requests to disable URL-based session identifiers.
*/
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
// skip non-http requests
        if (!(request instanceof HttpServletRequest)) {
chain.doFilter(request, response);
return;
}
HttpServletRequest httpRequest = (HttpServletRequest) request;
HttpServletResponse httpResponse = (HttpServletResponse) response;
// clear session if session id in URL
        if (httpRequest.isRequestedSessionIdFromURL()) {
HttpSession session = httpRequest.getSession();
if (session != null) session.invalidate();
}
// wrap response to remove URL encoding
        HttpServletResponseWrapper wrappedResponse = new HttpServletResponseWrapper(httpResponse) {
@Override
public String encodeRedirectUrl(String url) {
return url;
}
@Override
public String encodeRedirectURL(String url) {
return url;
}
@Override
public String encodeUrl(String url) {
return url;
}
@Override
public String encodeURL(String url) {
return url;
}
};
// process next request in chain
        chain.doFilter(request, wrappedResponse);
}
/**
* Unused.
*/
public void init(FilterConfig config) throws ServletException {
}
/**
* Unused.
*/
public void destroy() {
}