Download CSCI 6962: Server-side Design and Programming

CSCI 6962:
Server-side Design and Programming
Introduction to Java
Server Faces
Outline
•
•
•
•
•
Model-based architectures and value binding
Creating JSF page and managed beans in NetBeans
Adding member variables to managed beans
Basic JSF tags
Binding variables to JSF form elements
Java Server Faces
• Model-based architecture
JJava
Server
Faces
page
User interface
components
Managed
Bean
Support class
JJSF
JBean
JJSF
JBean
• Data storage and
manipulation
• Validation
• Navigation and
redirection
• Long term data
storage (sessions,
databases, etc.)
Java Server Faces
Value Binding
• Form elements can be directly linked to variables inside bean
• Changing values on form changes value of those variables when
form submitted
Creating a JSF
• New Project  Java Web 
Web Application
Enter name and press NEXT twice (not finish)
• Check Java Server Faces
under Frameworks
Creating a JSF Page
• New File  Web  JSF Page
• Make sure Facelets selected
Creating a Managed Bean
• New File  Java Server Faces
 JSF Managed Bean
• Give it a name and a
package
• Set its scope to request
(for now)
Managed Beans
• Generated bean file contains
– Name that any JSF can use
to refer to it
– Scope for which bean exists
• Request (single page)
• Session (multiple pages in
same user session)
• Application (accessible by
all user sessions)
Defining Member Variables
• Data stored or
computed by bean
• Any form elements
bean binds to
• Must be type String
for text elements
Getter/Setter Methods
• Each member variable variable should have methods
– public String getVariable()
– public void setVariable(String)
• Required if variable bound to form element
– Get called when page loaded to insert value
– Set called when form submitted to change bean value
• Done “behind the scenes” with request.getParameter
calls
Getter/Setter Methods
• Can use ALT-INSERT to
do automatically
Java Server Faces Tags
• JSF tags instead of html
Java Server Faces Tags
• JSF tags instead of html
– Tags of form <h:tagname…> or <f:tagname…>
(XML syntax)
– Many similar in form to html tags
– Tag libraries set in enclosing html tag
– Reference:
http://docs.oracle.com/javaee/6/javaserverfaces/2.0/docs/pdldocs/facelets/
Java Server Faces Tags
• Translated to html in response sent to client
JSF Text Input
• Goal: Bind input field to member variable in bean
– Form submitted  variable value updated automatically
– Page sent back as response  variable value automatically
inserted
• Syntax:
<h: inputText
value=‘#{beanname.variablename}’/>
JSF Text Output
• Like input field, but “read only”
– Variable value automatically inserted into response
– Translated into simple text
• Syntax:
<h: outputLabel value=‘#{beanname.variablename}’/>
JSF Submit Buttons
• Syntax:
<h:commandButton value=‘label on button'
action=“page to redirect to"/>
• Note that address defined in button rather than form
– Crucial for bean-directed redirection
Computed Values
• Can bind to computed values instead of bean variables
• Example:
– Bean computes cost of widget order
– Receipt gets and displays that value
Computed Values
• Must define get and set method for input field
• Must define set method for input field
Cost not a member
variable
getCost computed
from member
variables
Initial Values
• Can load values into form elements when page loaded
• Assign corresponding bean variables initial values
JSF/Bean Lifecycle
Request for JSF page
(initial form request)
JJSF
Jhtml
Sent as
html
form
Form
submitted
bean constructed (if
it does not already
exist)
bean values loaded
into bound elements
using get methods
Parameter
values parsed parameter values
JBean
from bound elements
stored in bean using
set methods