public class ImportFunctions extends TagHandler
The <o:importFunctions>
allows the developer to have access to all functions of the given
fully qualified name of a type in the EL scope using the usual EL functions syntax without the need to register them
in .taglib.xml
file. The functions are those public static
methods with a
non-void
return type. For example:
<o:importFunctions type="java.lang.Math" var="m" /> <o:importFunctions type="org.omnifaces.util.Faces" /> ... #{m:abs(-10)} #{m:max(bean.number1, bean.number2)} ... <base href="#{Faces:getRequestBaseURL()}" />
The functions prefix becomes by default the simple name of the type. You can override this by explicitly
specifying the var
attribute. If there are multiple function methods with exactly the same name, then
the one with the least amount of parameters will be used. If there are multiple function methods with exactly the
same name and amount of parameters, then the choice is unspecified (technically, JVM-dependent) and should not be
relied upon. So if you absolutely need to differentiate functions in such case, give them each a different name.
Note that the colon :
operator to invoke the method is as required by EL functions spec. It's by
design not easily possible to change it to the period .
operator. Also note that in case of
org.omnifaces.util.Faces
it's considered poor practice if the same functionality is already available
through the implicit EL variables #{facesContext}
, #{view}
, #{request}
, etc
such as #{request.contextPath}
which should be preferred over
#{Faces:getRequestContextPath()}
.
The resolved functions are by reference stored in the cache to improve retrieving performance.
nextHandler, tag, tagId
Constructor and Description |
---|
ImportFunctions(TagConfig config)
The tag constructor.
|
Modifier and Type | Method and Description |
---|---|
void |
apply(FaceletContext context,
UIComponent parent)
Register a new
FunctionMapper which checks if the given prefix matches our own var and then
find the associated method based on the given method name. |
getAttribute, getRequiredAttribute, toString
public ImportFunctions(TagConfig config)
config
- The tag config.public void apply(FaceletContext context, UIComponent parent) throws IOException
FunctionMapper
which checks if the given prefix matches our own var
and then
find the associated method based on the given method name.IOException