ADF培训_25_Page_FlowScopes_2009.pptVIP

Insert Picture Here Section 25 ADF Controller Flow Scopes 25 It’s a Matter of Scope This is the most important thing… Task flows have a private memory scope - PageFlowScope Plus the usual request, session and application scopes Accessed via expression language like the other scopes - #{pageflowScope.bean} Private to each flow (and instance of a flow) This allows nesting and reuse Data mapped in and out in call activities and task flow returns ADF Controller Memory Scopes Application Attributes and managed beans are available for an entire application and shared among users Information should not have session dependency Session Attributes and beans are user instance specific, and exist from the time of their creation to the time they are deleted or the session ends Example usecase is a user info bean that stores information about a user to avoid unnecessary queries ADF Controller Memory Scopes PageFlow Available for the duration of a task flow Exited when exiting the task flow If used with nested task flows, the PageFlow scope of the caller flow is suspended and activated upon return from the called Task Flow PageFlow scope is not available until after the JavaServer Faces Restore View phase View Stores objects used by a single page Automatically released when the user leaves the page. A View scope instance exists for each view that the ADF Controller manages The lifetime begins and ends with the change of the view id of a view port ADF Controller Memory Scopes Request Represents the smallest available scope Lasts for the time it takes to transition from one view activity to the next BackingBean Special case of request scope Associated with a specific manage bean instance Used with declarative components, regions and page fragments that use a managed bean to hold view state information Allows multiple instances of the component to co-exist on a single page None Use for beans that don’t require to keep state so that bean does not need to remain in memory Avai