How to use a servlet filter in Java to change an incoming servlet request url

Question

How can I use a servlet filter to change an incoming servlet request url from  http   nm-java appspot com Check License Dir My App Dir ABC My Obj 123  to  http   nm-java appspot com Check License Contact Id My Obj 123       Update  according to BalusC s steps below  I came up with the following code   public class UrlRewriteFilter implements Filter         Override     public void init FilterConfig config  throws ServletException                          Override     public void doFilter ServletRequest req  ServletResponse res  FilterChain chain  throws ServletException  IOException           HttpServletRequest request    HttpServletRequest  req          String requestURI   request getRequestURI             if  requestURI startsWith   Check License Dir My App                   String toReplace   requestURI substring requestURI indexOf   Dir My App    requestURI lastIndexOf        1               String newURI   requestURI replace toReplace    Contact Id                 req getRequestDispatcher newURI  forward req  res             else               chain doFilter req  res                         Override     public void destroy                          The relevant entry in web xml look like this    lt filter gt       lt filter-name gt urlRewriteFilter lt  filter-name gt       lt filter-class gt com example UrlRewriteFilter lt  filter-class gt   lt  filter gt   lt filter-mapping gt       lt filter-name gt urlRewriteFilter lt  filter-name gt       lt url-pattern gt    lt  url-pattern gt   lt  filter-mapping gt    I tried both server-side and client-side redirect with the expected results  It worked  thanks BalusC

User · Accepted Answer

Implement javax servlet Filter  In doFilter   method  cast the incoming ServletRequest to HttpServletRequest  Use HttpServletRequest getRequestURI   to grab the path  Use straightforward java lang String methods like substring    split    concat   and so on to extract the part of interest and compose the new path  Use either ServletRequest getRequestDispatcher   and then RequestDispatcher forward   to forward the request response to the new URL  server-side redirect  not reflected in browser address bar   or cast the incoming ServletResponse to HttpServletResponse and then HttpServletResponse sendRedirect   to redirect the response to the new URL  client side redirect  reflected in browser address bar   Register the filter in web xml on an url-pattern of    or  Check License    depending on the context path  or if you re on Servlet 3 0 already  use the  WebFilter annotation for that instead    Don t forget to add a check in the code if the URL needs to be changed and if not  then just call FilterChain doFilter    else it will call itself in an infinite loop   Alternatively you can also just use an existing 3rd party API to do all the work for you  such as Tuckey s UrlRewriteFilter which can be configured the way as you would do with Apache s mod rewrite

User · Answer

You could use the ready to use Url Rewrite Filter with a rule like this one    lt rule gt     lt from gt   Check License Dir My App Dir ABC My Obj   0-9     lt  from gt     lt to gt  Check License Contact Id My Obj  1 lt  to gt   lt  rule gt    Check the Examples for more    examples

User · Answer

A simple JSF Url Prettyfier filter based in the steps of BalusC s answer  The filter forwards all the requests starting with the  ui path  supposing you ve got all your xhtml files stored there  to the same path  but adding the xhtml suffix   public class UrlPrettyfierFilter implements Filter        private static final String JSF VIEW ROOT PATH     ui        private static final String JSF VIEW SUFFIX     xhtml         Override     public void destroy                  Override     public void doFilter ServletRequest request  ServletResponse response  FilterChain chain              throws IOException  ServletException           HttpServletRequest httpServletRequest     HttpServletRequest  request           String requestURI   httpServletRequest getRequestURI              Only process the paths starting with  ui  so as other requests get unprocessed             You can register the filter itself for  ui   only  too         if  requestURI startsWith JSF VIEW ROOT PATH                    amp  amp   requestURI contains JSF VIEW SUFFIX                 request getRequestDispatcher requestURI concat JSF VIEW SUFFIX                    forward request response             else               chain doFilter httpServletRequest  response                         Override     public void init FilterConfig arg0  throws ServletException

[java] How to use a servlet filter in Java to change an incoming servlet request url?

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