Since the release of JSR 286: Portlet Specification 2.0, it is possible to intercept and manipulate the request and response before they are delivered to a portlet in a given phase. Using Portlet filters you can block the rendering of a portlet if a specific condition occurs. Also, you can use portlet filters to decorate a request and a response within a wrapper to modify the behavior of the 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
}
}
<?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>
The portlet container for WebSphere® Application Server extends the portlet filter feature, which is provided by JSR 286, to allow you to register filters on a global level. These global filters apply to all portlets that are running within the portlet container, including both plain portlets and console modules.
<?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>