Serializable
This interface specifies a backing file. A backing file is a simple Java class implementing this
interface that has been wired to a portal element in the .portal file.
Backing files work in conjunction with JSPs. The JSPs allow the developer to code the presentation logic,
while the backing files allows the developer to code simple business logic. Backing files are always run before the JSPs.
A backing file has a lifecycle with four methods (see below). These methods are run 'in order' on all objects.
The developer may affect the underlying object from the BackingContext
. The BackingContext
should be
used from the backing file and the PresentationContext
should be used from the JSPs.
Alternately the developer can extend the AbstractJspBacking
file instead of implementing this interface.
Typically a new instance of this class (backing file) is created per request and is not shared across
books/pages/portlets. If, however, 'threadsafe' is marked as true on the JspContent
control a shared instance will be used. This instance is shared even across multiple requests. A slight performance
boost can be gained by setting the 'threadsafe' attribute to true as a new instance need not be created per each
request. However, any instance variables will need to be synchronized if not threadsafe. It is also recommended
to use this setting with caution when your backing file is registered to receive portlet events.
Related Topics
AbstractJspBacking
BackingContext
PortletBackingContext
BookBackingContext
PageBackingContext
AbstractJspBacking
Serializable
Method Summary |
public void |
|
public boolean |
|
public void |
|
public boolean |
|
Method Detail |
public void dispose()
This method is called at the end of serving the request, after the JSP has rendered.
public boolean handlePostbackData(HttpServletRequest
request,HttpServletResponse
response)
The purpose of this method is to let an implementation process request data.
This method should return true
if it changes the
window mode, window state, or the current page.
public void init(HttpServletRequest
request,HttpServletResponse
response)
This method is called once per request, and backing files can do request-scoped initialization by implementing this method. This method is run on the window (book/page/portlet) even if the window is not currently on a selected page.
public boolean preRender(HttpServletRequest
request,HttpServletResponse
response)
This method is called before rendering the JSP that this backing file is associated with. This method will not be run if the book/page/portlet is not being rendered (displayed). This is useful if heavy business logic only needs to be run if this portlet is on a selected page.
This method should return true
to let the framework render
the JSP. If this method returns false
, the framework
will not render the content JSP.
Note: if you don't want the Window (book, page or portlet) to render at all,
call setVisible(false)
on the backing context.
Related Topics
BackingContext
PortletBackingContext
BookBackingContext
PageBackingContext