javax.portlet

Class GenericPortlet

Implemented Interfaces:
Portlet, PortletConfig

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:

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.
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.
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.

Constructor Details

GenericPortlet

public GenericPortlet()
Does nothing.

Method Details

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

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

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

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

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

getInitParameter

public 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

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.

getPortletConfig

public PortletConfig getPortletConfig()
Returns the PortletConfig object of this portlet.
Returns:
the PortletConfig object of this portlet

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

getPortletName

public String getPortletName()
Returns the name of this portlet.
Specified by:
getPortletName in interface PortletConfig
Returns:
the portlet name

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
Returns:
the resource bundle for the given locale

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

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.

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.

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

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