javax.portlet
public interface Portlet
Portlet
interface is used by the portlet container to
invoke the portlets. Every portlet has to implement this interface,
either by directly implementing it, or by using an existing class
implementing the Portlet interface.
A portlet is a Java technology-based web component. It is managed by the portlet container and processes requests and generates dynamic content as response. Portlets are used by portals as pluggable user interface components.
The content generated by a portlet is called a fragment. A fragment is a piece of markup (e.g. HTML, XHTML, WML) adhering to certain rules and can be aggregated with other fragments into a complete document. The content of a portlet is normally aggregated with the content of other portlets into the portal page.
The portlet container instanciates portlets, manages their lifecycle and invoking them to process requests. The lifecycle consists of:
init
method
destroy
method
Request processing is divided into two types:
processAction
method,
to perform actions targeted to the portlet
render
method,
to perform the render operation
Method Summary | |
---|---|
void | destroy()
Called by the portlet container to indicate to a portlet that the
portlet is being taken out of service.
|
void | init(PortletConfig config)
Called by the portlet container to indicate to a portlet that the
portlet is being placed into service.
|
void | processAction(ActionRequest request, ActionResponse response)
Called by the portlet container to allow the portlet to process
an action request. |
void | render(RenderRequest request, RenderResponse response)
Called by the portlet container to allow the portlet to generate
the content of the response based on its current state.
|
Before the portlet container calls the destroy method, it should allow any threads that are currently processing requests within the portlet object to complete execution. To avoid waiting forever, the portlet container can optionally wait for a predefined time before destroying the portlet object.
This method enables the portlet to do the following:
The portlet container calls the init
method exactly once after instantiating the portlet.
The init
method must complete successfully
before the portlet can receive any requests.
The portlet container cannot place the portlet into service
if the init
method
PortletException
Parameters: config a PortletConfig
object
containing the portlet's
configuration and initialization parameters
Throws: PortletException if an exception has occurred that interferes with the portlet's normal operation. UnavailableException if the portlet cannot perform the initialization at this time.
RenderResponse.createActionURL()
method.
Typically, in response to an action request, a portlet updates state based on the information sent in the action request parameters. In an action the portlet may:
A client request triggered by an action URL translates into one action request and many render requests, one per portlet in the portal page. The action processing must be finished before the render requests can be issued.
Parameters: request the action request response the action response
Throws: PortletException if the portlet has problems fulfilling the request UnavailableException if the portlet is unavailable to process the action at this time PortletSecurityException if the portlet cannot fullfill this request because of security reasons IOException if the streaming causes an I/O problem
Parameters: request the render request response the render response
Throws: PortletException if the portlet has problems fulfilling the rendering request UnavailableException if the portlet is unavailable to perform render at this time PortletSecurityException if the portlet cannot fullfill this request because of security reasons java.io.IOException if the streaming causes an I/O problem