Class GenericPortlet

java.lang.Object
javax.portlet.GenericPortlet
All Implemented Interfaces:
Portlet, PortletConfig
public abstract class GenericPortlet extends 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.

  • Field Details

  • Constructor Details

    • GenericPortlet

      public GenericPortlet()
      Does nothing.

  • Method Details

    • 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, 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
      IOException - if the streaming causes an I/O problem

    • render

      public void render(RenderRequest request, RenderResponse response) throws PortletException, 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
      IOException - if the streaming causes an I/O problem

    • getTitle

      protected 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, 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
      IOException - if the streaming causes an I/O problem
      See Also:

    • doView

      protected void doView(RenderRequest request, RenderResponse response) throws PortletException, 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
      IOException - if the streaming causes an I/O problem

    • doEdit

      protected void doEdit(RenderRequest request, RenderResponse response) throws PortletException, 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
      IOException - if the streaming causes an I/O problem

    • doHelp

      protected void doHelp(RenderRequest request, RenderResponse response) throws PortletException, 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
      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 String getPortletName()
      Returns the name of this portlet.
      Specified by:
      getPortletName in interface PortletConfig
      Returns:
      the portlet name
      See Also:

    • 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:

    • getResourceBundle

      public ResourceBundle getResourceBundle(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 String getInitParameter(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:
      IllegalArgumentException - if name is null.

    • getInitParameterNames

      public 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.