Hi Feilong,
Yes, use
Servlet-filter and servlet-filter-mappings hooksAbstracted from the
Lifery DEV book:
The portal created a delegation filter to handle all servlet filtering needs. This allows dynamically adding new servlet filters and servlet filters mapping, or overriding existing servlet filters and servlet filters mapping. Current filters and mappings are moved to the XML file liferay-filter-web.xml, read by this filter. Basically this filter takes over the job of servlet container and allows optimizing in addition to adding new filters dynamically.
For instance, to add new servlet filter Knowledge Base Filter, you can leverage servlet filters and servlet filters mapping hooks. First, you could add servlet filters and servlet filters mappings in the liferay-hook.xml as follows.
<hook>
<servlet-filter>
<servlet-filter-name>Knowledge Base Filter</servlet-filter-name>
<servlet-filter-impl>com.liferay.knowledgebase.hook.filter.KBFilter</servlet-filter-impl>
<init-param>
<param-name>knowledge</param-name>
<param-value>base</param-value>
</init-param>
</servlet-filter>
<servlet-filter-mapping>
<servlet-filter-name>Knowledge Base Filter</servlet-filter-name>
<before-filter>SSO Open SSO Filter</before-filter>
<url-pattern>/group/*</url-pattern>
<url-pattern>/user/*</url-pattern>
<url-pattern>/web/*</url-pattern>
<url-pattern>*.jsp</url-pattern>
<dispatcher>REQUEST</dispatcher>
<dispatcher>FORWARD</dispatcher>
</servlet-filter-mapping>
</hook>
Then you should provide servlet filter implementation class com.liferay.knowledgebase.hook.filter.KBFilter. Note that the servlet filter class does implement the interface Filter as follows.
public void destroy() {
// add custom logic
}
public void doFilter(
ServletRequest servletRequest, ServletResponse servletResponse,
FilterChain filterChain)
throws IOException, ServletException {
String uri = (String)servletRequest.getAttribute(
WebKeys.INVOKER_FILTER_URI);
// see details in KBFilter.java
filterChain.doFilter(servletRequest, servletResponse);
}
public void init(FilterConfig filterConfig) {
System.out.println(
"Called KBFilter.init(" + filterConfig + ") where knowledge=" +
filterConfig.getInitParameter("knowledge"));
// add custom logic
}
As you can see, the class KBFilter must implement the methods of the interface Filter: destroy, init and doFilter. Filters perform filtering in the doFilter method. Every Filter like KBFilter has access to a FilterConfig object from which it can obtain its initialization parameters like “knowledge”, a reference to the ServletContext which it can use.
Hope that it helps
Jonas
==================
The Author of Liferay Books:
Liferay User Interface DevelopmentLiferay Portal 6 Enterprise IntranetsLiferay Portal 5.2 Systems DevelopmentLiferay Portal Enterprise Intranets
