javax.portlet
Class GenericPortlet

java.lang.Object
  javax.portlet.GenericPortlet

All Implemented Interfaces:

Portlet, PortletConfig

Direct Known Subclasses:

AnnouncementPortlet, DailyDilbertPortlet, ImportantFactPortlet, LoginPortlet, MoonPhasePortlet, MyLinksPortlet, PrincessWebCamPortlet, RegressionTestPortlet, RestaurantPortlet, RSSPortlet, SecureEditPortlet, SiteTrafficPortlet, StockQuotePortlet, SystemInfoPortlet, WeatherChannelPortlet

public abstract class GenericPortlet

extends java.lang.Object

implements Portlet, PortletConfig

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 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	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	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	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.
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.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.
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	render(RenderRequest request, RenderResponse response) The default implementation of this method sets the title using the getTitle method and invokes the doDispatch method.

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 just stores the PortletConfig object.

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 title using the getTitle method and invokes the doDispatch method.

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

doDispatch

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

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