org.omnifaces.taghandler
Class ImportConstants

java.lang.Object
  javax.faces.view.facelets.TagHandler
      org.omnifaces.taghandler.ImportConstants

All Implemented Interfaces:

javax.faces.view.facelets.FaceletHandler

public class ImportConstants
extends javax.faces.view.facelets.TagHandler

The <o:importConstants> allows the developer to have a mapping of all constant field values of the given fully qualified name of a type in the EL scope. The constant field values are those public static final fields. This works for classes, interfaces and enums. For example:

 public class Foo {
     public static final String FOO1 = "foo1";
     public static final String FOO2 = "foo2";
 }

 public interface Bar {
     public String BAR1 = "bar1";
     public String BAR2 = "bar2";
 }

 public enum Baz {
     BAZ1, BAZ2;
 }
 

The constant field values of the above types can be mapped into the EL scope as follows:

 <o:importConstants type="com.example.Foo" />
 <o:importConstants type="com.example.Bar" />
 <o:importConstants type="com.example.Baz" var="Bazzz" />
 ...
 #{Foo.FOO1}, #{Foo.FOO2}, #{Bar.BAR1}, #{Bar.BAR2}, #{Bazzz.BAZ1}, #{Bazzz.BAZ2}
 

The map is by default stored in the EL scope by the simple name of the type as variable name. You can override this by explicitly specifying the var attribute, as demonstrated for com.example.Baz in the above example.

The resolved constants are by reference stored in the cache to improve retrieving performance.

Author:

Bauke Scholtz

Field Summary

Fields inherited from class javax.faces.view.facelets.TagHandler

nextHandler, tag, tagId

Constructor Summary

ImportConstants(javax.faces.view.facelets.TagConfig config)
The tag constructor.

Method Summary

void	apply(javax.faces.view.facelets.FaceletContext context, javax.faces.component.UIComponent parent) First obtain the constants of the class by its fully qualified name as specified in the type attribute from the cache.

Methods inherited from class javax.faces.view.facelets.TagHandler

getAttribute, getRequiredAttribute, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

ImportConstants

public ImportConstants(javax.faces.view.facelets.TagConfig config)

The tag constructor.

Parameters:

config - The tag config.

Method Detail

apply

public void apply(javax.faces.view.facelets.FaceletContext context,
                  javax.faces.component.UIComponent parent)
           throws java.io.IOException

First obtain the constants of the class by its fully qualified name as specified in the type attribute from the cache. If it hasn't been collected yet and is thus not present in the cache, then collect them and store in cache. Finally set the constants in the EL scope by the simple name of the type, or by the name as specified in the var attribute, if any.

Throws:

java.io.IOException