Can I exclude some concrete urls from <url-pattern> inside <filter-mapping>?
I want some concrete filter to be applied for all urls except for one concrete (i.e. for /* except for /specialpath).
Is there a possibility to do that?
sample code:
<filter>
<filter-name>SomeFilter</filter-name>
<filter-class>org.somproject.AFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>SomeFilter</filter-name>
<url-pattern>/*</url-pattern> <!-- the question is: how to modify this line? -->
<dispatcher>REQUEST</dispatcher>
<dispatcher>FORWARD</dispatcher>
</filter-mapping>
Answer
The standard Servlet API doesn't support this facility. You may want either to use a rewrite-URL filter for this like Tuckey's one (which is much similar Apache HTTPD's mod_rewrite), or to add a check in the doFilter() method of the Filter listening on /*.
String path = ((HttpServletRequest) request).getRequestURI();
if (path.startsWith("/specialpath/")) {
chain.doFilter(request, response); // Just continue chain.
} else {
// Do your business stuff here for all paths other than /specialpath.
}
You can if necessary specify the paths-to-be-ignored as an init-param of the filter so that you can control it in the web.xml anyway. You can get it in the filter as follows:
private String pathToBeIgnored;
public void init(FilterConfig config) {
pathToBeIgnored = config.getInitParameter("pathToBeIgnored");
}
If the filter is part of 3rd party API and thus you can't modify it, then map it on a more specific url-pattern, e.g. /otherfilterpath/* and create a new filter on /* which forwards to the path matching the 3rd party filter.
String path = ((HttpServletRequest) request).getRequestURI();
if (path.startsWith("/specialpath/")) {
chain.doFilter(request, response); // Just continue chain.
} else {
request.getRequestDispatcher("/otherfilterpath" + path).forward(request, response);
}
To avoid that this filter will call itself in an infinite loop you need to let it listen (dispatch) on REQUEST only and the 3rd party filter on FORWARD only.