JavaWeb中URL上的jsessionid

FYI :
http://www.blogjava.net/steady/archive/2007/09/08/143664.html
http://randomcoder.com/articles/jsessionid-considered-harmful

上列網頁中提到，透過加入 Filter 的方式過滤掉 URL 中包含的 jsessionid，再重新包装 Response 返回给瀏覽器。
以解決jsessionid在URL出現的問題。

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.
** Copyright (c) 2006, Craig Condit. All rights reserved.

*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
*  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.
*
* 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.
* 

*/
@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() {
}