JSF Tags

JSF application typically uses JSP pages to represent views. JSF provides useful special tags to enhance these views. Each tag gives rise to an associated component. JSF provides 43 tags in two standard JSF tag libraries:

1. JSF Core Tags  Library and 

2. JSF Html Tags Library

Even a very simple page uses tags from both libraries.

<%@ taglib uri=”http://java.sun.com/jsf/core “ prefix=”f” %>
<%@ taglib uri=”http://java.sun.com/jsf/html “ prefix=”h” %>
<f:view>
<h:form>
……………
……………
</h:form>
</f:view>

In the above code fragment we have imported two JSF tag libraries with the help of taglib directive. JSF Core Tag Library contains set of JSF core tags while JSF Html Tags Library contains set of html tags. Prefix is used to use tags defined in tag library. Here we are using conventional names f and h for Core & Html tags respectively. We have the choice to choose any name for the prefixes. 

• JSF Html Tags:
  
  These tags represent html components like text fields, buttons, form.
  Html tags can be divided into following categories:
  
  Inputs                           (inputText, inputTextarea)
  Outputs                        (outputText, outputLabel)
  Commands                   (commandButton)
  Selections                    (selectOneRadio, selectOneListbox, selectOneMenu for radio buttons, list boxes, menu etc)
  Layouts                        (panelGrid)
  Data table                    (dataTable)
  Errors and messages   (message, messages)
  
  Some examples have been given below to understand how to use these tags and its attributes:

          <h:inputText id=”ID1” value=”value”/>                 
  creates a single line text input control  where  id attribute is used to uniquely identify the component rendered by this tag and value attribute sets the current value of the component.  

           <h:outputText id="ID2" value="Welcome"/>
  creates a single line text output where id attribute uniquely identifies the rendered component and current value is set by value attribute .
  
           <h:commandButton                                             
                         id="submit"
                         value="go"
                         action="nextPage">
             </h:commandButton> 
  
  creates a command button where value attribute sets the value that is displayed on the button when it is rendered and action attribute is used to invoke a method defined in backing bean when a user does an action on the component .According to the return of the invoked method it is determined which view is to be displayed next.
  
  In JSF Html Tag Library there are 25 core tags .

  All JSF Html Tags :

  • column                              creates column in a dataTable
  • commandButton                creates button
  • commandLink                   creates link that acts like a pushbutton
  • dataTable                         creates a  table control
  • form                                 creates a form
  • graphicImage                    displays an image
  • inputHidden                      creates hidden field
  • inputSecret                       creates input control for password
  • inputText                          creates  text input control (single line)
  • inputTextarea                    creates  text input control (multiline)
  • message                           displays the most recent message for a component
  • messages                          displays all messages
  • outputFormat                    creates  outputText, but formats compound messages
  • outputLabel                      creates label 
  • outputLink                        creates anchor
  • outputText                        creates single line text output
  • panelGrid                         creates html table with specified number of columns
  • panelGroup                      used to group other components where the specification requires one child element
  • selectBooleanCheckbox   creates checkbox
  • selectManyCheckbox       creates set of checkboxes
  • selectManyListbox           creates multiselect listbox
  • selectManyMenu              creates multiselect menu
  • selectOneListbox              creates single select listbox
  • selectOneMenu                creates single select menu
  • selectOneRadio                creates set of radio buttons
    

•  JSF Core Tags:
  
  These tags allows you to take advantages of features of JSF framework, like validation, conversion , event handling. Core library is stepchild of Html library. i.e. core library supports the html library. Core tag library also contains tags for views and sub-views , loading resource bundle, adding arbitrary text to a page. Some examples of JSF core tags are:
  
  f: view  tag is used to create top level view
  f: subview tag is used to create subview of  a view.
  f: validator tag is used to add a validator to a component.
  f: converter tag is used to add an arbitrary converter to a component.
  f: actionListener tag is used to add an action listener to a component.
  f:valueChangeListener tag is used to add a valuechange listener to a component
  
  Some examples have been given below to understand how to use these tags:
  
  <f:view locale="en">
      <h:outputText value="label" />
  </f:view>
  f: view  tag is used to create top level view and is a container for all JSF component tags on a page. Where locale attribute  provides several options for presenting  localized views of your application. Here "en" represents English and if we give velue "fr" to locale attribute then french view will be displayed. So this attribute is useful for internationalization purpose.
  
  <f:view>
    <h1>head</h1>
    <p>view</p>
    <f:subview id="sub_id">
      <c:import url="second.jsp" />
     </f:subview>
  </f:view>
  Here f:subview tag is like container for the JSF components contained in an included JSP page (second.jsp).

  <h:inputText id="txt_id" 
               value="txt_value">
    <f:validator validatorId="Txt_Validator" /> 
  </h:inputText> 
  The Validator tag registers a  Validator  on the component associated with the enclosing tag. In validatorId field, we give the value of one of the validator-id element of a validator in your Faces configuration file.

In JSF Core Tag Library there are 18 core tags .

All JSF Core Tags:

• f :view                                 Creates the top-level view
• f:subview                             Creates a subview of a view
• f:attribute           Adds an attribute  to a component
• f:param                                Constructs a parameter component
• f:converter            Adds an arbitrary converter to a component
• f:converterDateTime      Adds a datetime converter to a component
• f:converterNumber       Adds a number converter to a component
• f:actionListener          Adds an action listener to a component
• f:valueChangeListener     Adds a valuechange listener to a component
• f:validator              dds a validator to a component
• f:validateDoubleRange    Validates a double range for a component’s value
• f:validateLength         Validates the length of a component’s value
• f:validateLongRange      Validates a long range for a component’s value
• f:facet                 Adds a facet to a component
• f:loadBundle            Loads a resource bundle, stores properties as a Map
• f:selectitems            Specifies items for a select one or select many component
• f:selectitem             Specifies an item for a select one or select many component
• f:verbatim              Adds markup to a JSF page