javax.portlet
Class GenericPortlet

java.lang.Object
  javax.portlet.GenericPortlet

All Implemented Interfaces:

EventPortlet, Portlet, PortletConfig, ResourceServingPortlet

Direct Known Subclasses:

AboutPortlet, GenericPlutoPortlet, TestPortlet

public abstract class GenericPortlet
extends java.lang.Object
implements Portlet, PortletConfig, EventPortlet, ResourceServingPortlet

The GenericPortlet class provides a default implementation for the Portlet interface.

It provides an abstract class to be subclassed to create portlets. A subclass of GenericPortlet should override at least one method, usually one of the following:

• processAction, to handle action requests
• doView, to handle render requests when in VIEW mode
• doEdit, to handle render requests when in EDIT mode
• doHelp, to handle render request when in HELP mode
• init and destroy, to manage resources that are held for the life of the servlet

Normally there is no need to override the render or the doDispatch methods. Render handles render requests setting the title of the portlet in the response and invoking doDispatch. doDispatch dispatches the request to one of the doView, doEdit or doHelp method depending on the portlet mode indicated in the request.

Portlets typically run on multithreaded servers, so please note that a portlet must handle concurrent requests and be careful to synchronize access to shared resources. Shared resources include in-memory data such as instance or class variables and external objects such as files, database connections, and network connections.

Constructor Summary

GenericPortlet()
Does nothing.

Method Summary

void	destroy() Called by the portlet container to indicate to a portlet that the portlet is being taken out of service.
protected void	doDispatch(RenderRequest request, RenderResponse response) The default implementation of this method routes the render request to: method annotated with @RenderMode and the name of the portlet mode a set of helper methods depending on the current portlet mode the portlet is currently in.
protected void	doEdit(RenderRequest request, RenderResponse response) Helper method to serve up the edit mode.
protected void	doHeaders(RenderRequest request, RenderResponse response) Used by the render method to set the response properties and headers.
protected void	doHelp(RenderRequest request, RenderResponse response) Helper method to serve up the help mode.
protected void	doView(RenderRequest request, RenderResponse response) Helper method to serve up the mandatory view mode.
java.lang.String	getDefaultNamespace() Returns the default namespace for events and public parameters.
java.lang.String	getInitParameter(java.lang.String name) Returns a String containing the value of the named initialization parameter, or null if the parameter does not exist.
java.util.Enumeration<java.lang.String>	getInitParameterNames() Returns the names of the portlet initialization parameters as an Enumeration of String objects, or an empty Enumeration if the portlet has no initialization parameters.
protected java.util.Collection<PortletMode>	getNextPossiblePortletModes(RenderRequest request) Used by the render method to set the next possible portlet modes.
PortletConfig	getPortletConfig() Returns the PortletConfig object of this portlet.
PortletContext	getPortletContext() Returns the PortletContext of the portlet application the portlet is in.
java.lang.String	getPortletName() Returns the name of this portlet.
java.util.Enumeration<javax.xml.namespace.QName>	getProcessingEventQNames() Returns the QNames of the processing events supported by the portlet as an Enumeration of QName objects, or an empty Enumeration if the portlet has not defined any processing events.
java.util.Enumeration<java.lang.String>	getPublicRenderParameterNames() Returns the names of the public render parameters supported by the portlet as an Enumeration of String objects, or an empty Enumeration if the portlet has no public render parameters.
java.util.Enumeration<javax.xml.namespace.QName>	getPublishingEventQNames() Returns the QNames of the publishing events supported by the portlet as an Enumeration of QName objects, or an empty Enumeration if the portlet has not defined any publishing events.
java.util.ResourceBundle	getResourceBundle(java.util.Locale locale) Gets the resource bundle for the given locale based on the resource bundle defined in the deployment descriptor with resource-bundle tag or the inlined resources defined in the deployment descriptor.
java.util.Enumeration<java.util.Locale>	getSupportedLocales() Returns the locales supported by the portlet as an Enumeration of Locale objects, or an empty Enumeration if the portlet has not defined any supported locales.
protected java.lang.String	getTitle(RenderRequest request) Used by the render method to get the title.
void	init() A convenience method which can be overridden so that there's no need to call super.init(config).
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	processEvent(EventRequest request, EventResponse response) Default event processing.
void	render(RenderRequest request, RenderResponse response) The default implementation of this method sets the headers using the doHeaders method, sets the title using the getTitle method and invokes the doDispatch method.
void	serveResource(ResourceRequest request, ResourceResponse response) Default resource serving.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

GenericPortlet

public GenericPortlet()

Does nothing.

Method Detail

init

public void init(PortletConfig config)
          throws PortletException

Called by the portlet container to indicate to a portlet that the portlet is being placed into service.

The default implementation stores the PortletConfig object and checks for annotated methods with the annotations

ProcessAction

ProcessEvent

RenderMode

and stores these in a hashmap for later dispatching.

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 does one of the following:

1. it throws a PortletException
2. it does not return within a time period defined by the Web server

Specified by:

init in interface Portlet

Parameters:

config - a PortletConfig object containing the portlet configuration and initialization parameters

Throws:

PortletException - if an exception has occurred that interferes with the portlet normal operation.

UnavailableException - if the portlet cannot perform the initialization at this time.

init

public void init()
          throws PortletException

A convenience method which can be overridden so that there's no need to call super.init(config).

Instead of overriding init(PortletConfig), simply override this method and it will be called by GenericPortlet.init(PortletConfig config). The PortletConfig object can still be retrieved via getPortletConfig().

Throws:

PortletException - if an exception has occurred that interferes with the portlet normal operation.

UnavailableException - if the portlet is unavailable to perform init

processAction

public void processAction(ActionRequest request,
                          ActionResponse response)
                   throws PortletException,
                          java.io.IOException

Called by the portlet container to allow the portlet to process an action request. This method is called if the client request was originated by a URL created (by the portlet) with the RenderResponse.createActionURL() method.

The default implementation throws an exception.

Specified by:

processAction in interface Portlet

Parameters:

request - the action request

response - the action response

Throws:

PortletException - if the portlet cannot 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

java.io.IOException - if the streaming causes an I/O problem

render

public void render(RenderRequest request,
                   RenderResponse response)
            throws PortletException,
                   java.io.IOException

The default implementation of this method sets the headers using the doHeaders method, sets the title using the getTitle method and invokes the doDispatch method.

It also evaluates the RENDER_PART request attribute and if set calls the doHeaders, getNextPossiblePortletModes and getTitle methods for the RENDER_HEADERS part and the doDispatch method for the RENDER_MARKUP part.
If the RENDER_PART request attribute is not set all of the above methods will be called.

Specified by:

render in interface Portlet

Parameters:

request - the render request

response - the render response

Throws:

PortletException - if the portlet cannot fulfilling the 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

getTitle

protected java.lang.String getTitle(RenderRequest request)

Used by the render method to get the title.

The default implementation gets the title from the ResourceBundle of the PortletConfig of the portlet. The title is retrieved using the 'javax.portlet.title' resource name.

Portlets can overwrite this method to provide dynamic titles (e.g. based on locale, client, and session information). Examples are:

• language-dependant titles for multi-lingual portals
• shorter titles for WAP phones
• the number of messages in a mailbox portlet

Returns:

the portlet title for this window

Throws:

java.lang.IllegalStateException - if no portlet config object is available

doDispatch

protected void doDispatch(RenderRequest request,
                          RenderResponse response)
                   throws PortletException,
                          java.io.IOException

The default implementation of this method routes the render request to:

1. method annotated with @RenderMode and the name of the portlet mode
2. a set of helper methods depending on the current portlet mode the portlet is currently in. These methods are:
   • doView for handling view requests
   • doEdit for handling edit requests
   • doHelp for handling help requests

If the window state of this portlet is minimized, this method does not invoke any of the portlet mode rendering methods.

For handling custom portlet modes the portlet should either use the @RenderMode annotation or override this method.

Parameters:

request - the render request

response - the render response

Throws:

PortletException - if the portlet cannot fulfilling the 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

See Also:

doView(RenderRequest, RenderResponse), doEdit(RenderRequest, RenderResponse), doHelp(RenderRequest, RenderResponse)

doView

protected void doView(RenderRequest request,
                      RenderResponse response)
               throws PortletException,
                      java.io.IOException

Helper method to serve up the mandatory view mode.

The default implementation throws an exception.

Parameters:

request - the portlet request

response - the render response

Throws:

PortletException - if the portlet cannot fulfilling the 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

doEdit

protected void doEdit(RenderRequest request,
                      RenderResponse response)
               throws PortletException,
                      java.io.IOException

Helper method to serve up the edit mode.

The default implementation throws an exception.

Parameters:

request - the portlet request

response - the render response

Throws:

PortletException - if the portlet cannot fulfilling the 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

doHelp

protected void doHelp(RenderRequest request,
                      RenderResponse response)
               throws PortletException,
                      java.io.IOException

Helper method to serve up the help mode.

The default implementation throws an exception.

Parameters:

request - the portlet request

response - the render response

Throws:

PortletException - if the portlet cannot fulfilling the 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

getPortletConfig

public PortletConfig getPortletConfig()

Returns the PortletConfig object of this portlet.

Returns:

the PortletConfig object of this portlet

destroy

public void destroy()

Called by the portlet container to indicate to a portlet that the portlet is being taken out of service.

The default implementation does nothing.

Specified by:

destroy in interface Portlet

getPortletName

public java.lang.String getPortletName()

Returns the name of this portlet.

Specified by:

getPortletName in interface PortletConfig

Returns:

the portlet name

See Also:

PortletConfig.getPortletName()

getPortletContext

public PortletContext getPortletContext()

Returns the PortletContext of the portlet application the portlet is in.

Specified by:

getPortletContext in interface PortletConfig

Returns:

the portlet application context

See Also:

PortletContext

getResourceBundle

public java.util.ResourceBundle getResourceBundle(java.util.Locale locale)

Gets the resource bundle for the given locale based on the resource bundle defined in the deployment descriptor with resource-bundle tag or the inlined resources defined in the deployment descriptor.

Specified by:

getResourceBundle in interface PortletConfig

Parameters:

locale - the locale for which to retrieve the resource bundle

Returns:

the resource bundle for the given locale

getInitParameter

public java.lang.String getInitParameter(java.lang.String name)

Returns a String containing the value of the named initialization parameter, or null if the parameter does not exist.

Specified by:

getInitParameter in interface PortletConfig

Parameters:

name - a String specifying the name of the initialization parameter

Returns:

a String containing the value of the initialization parameter

Throws:

java.lang.IllegalArgumentException - if name is null.

getInitParameterNames

public java.util.Enumeration<java.lang.String> getInitParameterNames()

Returns the names of the portlet initialization parameters as an Enumeration of String objects, or an empty Enumeration if the portlet has no initialization parameters.

Specified by:

getInitParameterNames in interface PortletConfig

Returns:

an Enumeration of String objects containing the names of the portlet initialization parameters, or an empty Enumeration if the portlet has no initialization parameters.

getProcessingEventQNames

public java.util.Enumeration<javax.xml.namespace.QName> getProcessingEventQNames()

Description copied from interface: PortletConfig

Returns the QNames of the processing events supported by the portlet as an Enumeration of QName objects, or an empty Enumeration if the portlet has not defined any processing events.

Processing events are defined in the portlet deployment descriptor with the supported-processing-event element.

Specified by:

getProcessingEventQNames in interface PortletConfig

Returns:

an Enumeration of QName objects containing the names of the processing events, or an empty Enumeration if the portlet has not defined any support for processing events in the deployment descriptor.

getPublishingEventQNames

public java.util.Enumeration<javax.xml.namespace.QName> getPublishingEventQNames()

Description copied from interface: PortletConfig

Returns the QNames of the publishing events supported by the portlet as an Enumeration of QName objects, or an empty Enumeration if the portlet has not defined any publishing events.

Publishing events are defined in the portlet deployment descriptor with the supported-publishing-event element.

Note that this call does not return any events published that have not been declared in the deployment descriptor as supported.

Specified by:

getPublishingEventQNames in interface PortletConfig

Returns:

an Enumeration of QName objects containing the names of the publishing events, or an empty Enumeration if the portlet has not defined any support for publishing events in the deployment descriptor.

getSupportedLocales

public java.util.Enumeration<java.util.Locale> getSupportedLocales()

Description copied from interface: PortletConfig

Returns the locales supported by the portlet as an Enumeration of Locale objects, or an empty Enumeration if the portlet has not defined any supported locales.

Supported locales are defined in the portlet deployment descriptor with the supported-locale element.

Specified by:

getSupportedLocales in interface PortletConfig

Returns:

an Enumeration of Locale objects containing the supported locales, or an empty Enumeration if the portlet has not defined any supported locales in the deployment descriptor.

serveResource

public void serveResource(ResourceRequest request,
                          ResourceResponse response)
                   throws PortletException,
                          java.io.IOException

Default resource serving.

The default implemention of this method is to call a RequestDispatcher.foward with the ResourceID of the ResourceRequest.

If no ResourceID is set on the resource URL the default implementation does nothing.

Specified by:

serveResource in interface ResourceServingPortlet

Parameters:

request - the resource request

response - the resource 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

Since:

2.0

processEvent

public void processEvent(EventRequest request,
                         EventResponse response)
                  throws PortletException,
                         java.io.IOException

Default event processing. Tries to dispatch to an event method with annotation
@ProcessEvent(name=) and the signature
public void (EventRequest, EventResponse) throws PortletException, java.io.IOException.

Specified by:

processEvent in interface EventPortlet

Parameters:

request - the event request

response - the event response

Throws:

PortletException - if the portlet has problems fulfilling the request

UnavailableException - if the portlet is unavailable to process the event 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

Since:

2.0

See Also:

EventPortlet.processEvent(javax.portlet.EventRequest, javax.portlet.EventResponse)

doHeaders

protected void doHeaders(RenderRequest request,
                         RenderResponse response)

Used by the render method to set the response properties and headers.

The portlet should override this method and set its response header using this method in order to ensure that they are set before anything is written to the output stream.

The default implemention of this method is emtpy.

Since:

2.0

getNextPossiblePortletModes

protected java.util.Collection<PortletMode> getNextPossiblePortletModes(RenderRequest request)

Used by the render method to set the next possible portlet modes.

The portlet should override this method and set the next possible portlet modes using this method in order to ensure that they are set before anything is written to the output stream.

The default implemention of this method returns null.

Since:

2.0

getPublicRenderParameterNames

public java.util.Enumeration<java.lang.String> getPublicRenderParameterNames()

Returns the names of the public render parameters supported by the portlet as an Enumeration of String objects, or an empty Enumeration if the portlet has no public render parameters.

Specified by:

getPublicRenderParameterNames in interface PortletConfig

Returns:

an Enumeration of String objects containing the names of the public render parameters, or an empty Enumeration if the portlet does not define any public render parameters.

See Also:

PortletConfig.getPublicRenderParameterNames()

getDefaultNamespace

public java.lang.String getDefaultNamespace()

Returns the default namespace for events and public parameters. This namespace is defined in the portlet deployment descriptor with the default-namespace element.

If no default namespace is defined in the portlet deployment descriptor this methods returns the XML default namespace XMLConstants.NULL_NS_URI.

Specified by:

getDefaultNamespace in interface PortletConfig

Returns:

the default namespace defined in the portlet deployment descriptor, or XMLConstants.NULL_NS_URI is non is defined.

See Also:

PortletConfig.getDefaultNamespace()