JSF Life Cycle
The two key stages of the life cycle are
Additional subphases inside the Execute phase support the complex component tree. This structure necessitates the orderly propagation of component data to beans, the conversion and validation of component data, and the handling of component events.
Execute Phase
The application view is constructed or rebuilt when the first request is performed during the execution phase. Other actions are carried out for subsequent requests, such as applying request parameter values, converting component values, validating component values, updating managed beans with component values, and invoking application logic.
The Execute phase is divided into six sub-phase, which are discussed below:
1. Restore View Phase
The JavaServer Faces implementation starts the Restore View phase when a request for a JavaServer Faces page is made, typically by action, like when a link or button component is clicked.
The JavaServer Faces implementation constructs the page's view during this stage, attaches event handlers and validators to view components, and saves the view in the FacesContext instance, which has all the data required to handle a single request. The FacesContext object is accessible to all the application's parts, event handlers, converters, and validators.
2. Apply Request Values Phase
Each component in the tree pulls its new value from the request parameters by utilizing its decode (processDecodes()) method after the component tree has been restored during a postback request. Each component then stores the value locally.
The JavaServer Faces implementation moves directly to the Render Response stage if any decoding methods or event listeners have invoked the renderResponse method on the current FacesContext instance.
The JavaServer Faces implementation sends any events queued during this stage to interested listeners.
The components are now set to their new values, and events and messages have been queued.
3. Process Validations Phase
JSF processes all validators registered on the component tree during this stage. It looks at the attribute rules for the component for validation and contrasts them with the local value kept for the component. The life cycle moves on to the render response phase and displays the same page again with the error message if the local value is wrong, and JSF adds an error message to the FacesContext object.
4. Update model values
In this phase, Following a valid data check, the JSF traverses the component tree and sets the necessary server-side object properties to the components' local values. JSF will update the bean properties that correspond to the input component's value attribute.
The render response phase of JSF begins if any updateModels methods call renderResponse on the current FacesContext instance.
5. Invoke application
In this phase, Any application-level actions, such as submitting a form or linking to another page, are handled by the JavaServer Faces implementation.
The JavaServer Faces implementation finally gives the Render Response phase control.
6. Render Response Phase
In this stage, JavaServer Faces creates the view and gives the proper resource the authority to render the pages.
If this is the first request, the component tree will be expanded to include the page's representations of the components. The components are already added to the tree and do not need to be added again if this is not the first request.
The original page is rendered again during this step if the request is a postback and errors were discovered during the Apply Request Values phase, Process Validations phase, or Update Model Values phase.
Render
The requested view is rendered in response to the client browser during this stage. View rendering is a procedure where HTML or XHTML is produced as the output. Therefore, a person can view it in a browser.
Frequently Asked Questions
What are Facelets in JSF?
Facelets tags are special tags JSF offers to build a common layout for a web application.
What are controllers in JSF Application?
"FacesServlet" is the central controller for the JSF application.
Which tag does JSF use to upload a file to a website?
In JSF, the tag is used to upload a file to the website. JSF utilises the HTML file type element. The file will receive this tag to receive input.
What are the various bean scopes available in JSF?
Different bean scopes, such as @RequestScoped, @NoneScoped, @ViewScoped, @SessionScoped, @ApplicationScoped, and @CustomScoped, are available in JSF.
What are the two phases of the life cycle?
Conclusion
Finally, you've concluded this article.
Congratulations!! You learned about JSF Life Cycle and how it works in this blog. You studied the working of the life cycle and its different phases.
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