Portlet filters

To use the portlet filter feature, you must first complete the following actions:

• Implement one or more of the following interfaces of the javax.portlet.filter package:
  • RenderFilter
  • ActionFilter
  • ResourceFilter
  • EventFilter
  You must implement the appropriate filter based on the method or phase of the portlet that you want to filter.
• Register the filter within the portlet.xml file for the portlets in your web application.

The following sample code illustrates a portlet filter to screen the processAction method of a portlet:

package my.pkg;

import java.io.IOException;

import javax.portlet.ActionRequest;
import javax.portlet.ActionResponse;
import javax.portlet.PortletException;
import javax.portlet.filter.ActionFilter;
import javax.portlet.filter.FilterChain;
import javax.portlet.filter.FilterConfig;

public class MyPortletFilter implements ActionFilter {
     public void init(FilterConfig config) throws PortletException {
          String myInitParameter = config.getInitParameter("myInitParameter");
          // ...
     }

     public void doFilter(ActionRequest request, ActionResponse response,
               FilterChain chain) throws IOException, PortletException {
          preProcess(request, response);
          chain.doFilter(request, response);
          postProcess (request, response);
     }

     private void preProcess(ActionRequest request, ActionResponse response) {
          //For example, create a javax.portlet.filter.PortletRequestWrapper here
     }

     public void destroy() {
          // free resources
     }
}

The following sample code illustrates how you can declare the previous portlet filter in the portlet.xml file:

<?xml version="1.0" encoding="UTF-8"?>
<portlet-app xmlns="http://java.sun.com/xml/ns/portlet/portlet-app_2_0.xsd" 
version="2.0" id="demo_app_id">
     <portlet >
          <portlet-name>MyPortlet1</portlet-name>
          <!-- [...] -->
     </portlet>

     <portlet >
          <portlet-name>MyPortlet2</portlet-name>
          <!-- [...] -->
     </portlet>

     <filter>
          <filter-name>PortletFilter</filter-name>
          <filter-class>my.pkg .MyPortletFilter</filter-class>
          <lifecycle>ACTION_PHASE</lifecycle>
          <init-param>
               <name>myInitParameter</name>
               <value>myValue</value>
          </init-param>
     </filter>

     <filter-mapping>
          <filter-name>PortletFilter</filter-name>
          <portlet-name>MyPortlet1</portlet-name>
          <portlet-name>MyPortlet2</portlet-name>
     </filter-mapping>

</portlet-app>

If you implement the RenderFilter interface, for example, add the <lifecycle>RENDER_PHASE</lifecycle> code to the filter section. This addition is analogous to the other filter interfaces. The following values are valid for the <lifecycle> parameter:

• RESOURCE_PHASE
• RENDER_PHASE
• EVENT_PHASE
• ACTION_PHASE

To use global portlet filters, add the following code to the root folder of your Java™ archive (JAR) file or in the WEB-INF directory of your web application and name it plugin.xml file:

<?xml version="1.0" encoding="UTF-8"?>
<?eclipse version="3.0"?>
<plugin id="portlet-filter-config" name="WS_Server" provider-name="IBM" 
version="1.0.0">

     <extension point="com.ibm.ws.portletcontainer.portlet-filter-config">

          <portlet-filter-config class-name="my.pkg.PortletFilter" order="22000">
               <description>Description of global PortletFilterImpl</description>
                    <lifecycle>ACTION_PHASE</lifecycle>
                    <lifecycle>EVENT_PHASE</lifecycle>
                    <lifecycle>RENDER_PHASE</lifecycle>
                    <lifecycle>RESOURCE_PHASE</lifecycle>
                    <init-param>
                         <name>MyInitParam1</name>
                         <value>MyInitValue1</value>
                    </init-param>
                    <init-param>
                         <name>MyInitParam2</name>
                         <value>MyInitValue2</value>
                    </init-param>
          </portlet-filter-config>
     </extension>
</plugin>

The order attribute of the portlet-filter-config element defines when in the filter chain to run the filter. The higher the value, the later the filter runs in the filter chain. Global filters are triggered before local portlet filters.