org.metawidget.faces.FacesUtils Maven / Gradle / Ivy
// Metawidget
//
// This file is dual licensed under both the LGPL
// (http://www.gnu.org/licenses/lgpl-2.1.html) and the EPL
// (http://www.eclipse.org/org/documents/epl-v10.php). As a
// recipient of Metawidget, you may choose to receive it under either
// the LGPL or the EPL.
//
// Commercial licenses are also available. See http://metawidget.org
// for details.
package org.metawidget.faces;
import java.io.IOException;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.faces.application.Application;
import javax.faces.component.UIComponent;
import javax.faces.component.UIViewRoot;
import javax.faces.context.FacesContext;
/**
* Utilities for working with Java Server Faces.
*
* @author Richard Kennard
*/
public final class FacesUtils {
//
// Public statics
//
/**
* Return true if the specified value conforms to the syntax requirements of a
* value binding expression.
*
* This method is a mirror of the one in UIComponentTag.isValueReference, but that
* one is deprecated so may be removed in the future.
*
* @param value
* The value to evaluate
* @throws NullPointerException
* if value is null
*/
public static boolean isExpression( String value ) {
return matchExpression( value ).matches();
}
public static Matcher matchExpression( String value ) {
return PATTERN_EXPRESSION.matcher( value );
}
/**
* @return the original String, not wrapped in #{...}. If the original String was not wrapped,
* returns the original String
*/
public static String unwrapExpression( String value ) {
Matcher matcher = PATTERN_EXPRESSION.matcher( value );
if ( !matcher.matches() ) {
return value;
}
return matcher.group( 2 );
}
/**
* @return the original String, wrapped in #{...}. If the original String was already wrapped,
* returns the original String
*/
public static String wrapExpression( String value ) {
if ( isExpression( value ) ) {
return value;
}
return EXPRESSION_START + unwrapExpression( value ) + EXPRESSION_END;
}
public static void render( FacesContext context, UIComponent component )
throws IOException {
if ( component == null || !component.isRendered() ) {
return;
}
component.encodeBegin( context );
if ( component.getRendersChildren() ) {
component.encodeChildren( context );
} else {
renderChildren( context, component );
}
component.encodeEnd( context );
}
/**
* @return true if the JSF version is 2 or above, false otherwise
*/
public static boolean isJsf2() {
return IS_JSF_2;
}
public static boolean isValidationFailed() {
FacesContext context = FacesContext.getCurrentInstance();
if ( isJsf2() ) {
return FacesContext.getCurrentInstance().isValidationFailed();
}
// Under JSF 1.2, any severity (even SEVERITY_INFO) is considered a validation error. See
// http://java.net/jira/browse/JAVASERVERFACES_SPEC_PUBLIC-1035
return context.getMaximumSeverity() != null;
}
public static boolean isPartialStateSavingDisabled() {
FacesContext context = FacesContext.getCurrentInstance();
return "false".equals( context.getExternalContext().getInitParameter( "javax.faces.PARTIAL_STATE_SAVING" ) );
}
/**
* Create a component using either the JSF 2.x
* createComponent( context, componentType, rendererType ) method, or the JSF 1.x
* createComponent( componentType ) method. The former can be important for JSF 2.x
* controls that need to dynamically include additional resources (such as JavaScript/CSS
* files). See this forum discussion.
*/
@SuppressWarnings( "unchecked" )
public static T createComponent( String componentType, String rendererType ) {
FacesContext context = FacesContext.getCurrentInstance();
Application application = context.getApplication();
// JSF 2.x
if ( isJsf2() ) {
return (T) application.createComponent( context, componentType, rendererType );
}
// JSF 1.x
return (T) application.createComponent( componentType );
}
/**
* Sets the given style and styleClass on the given Component.
*
* JSF does not provide a common interface for all UIComponents that support
* style and styleClass, so we must interrogate their attributes
* directly.
*/
public static void setStyleAndStyleClass( UIComponent component, String style, String styleClass ) {
Map attributes = component.getAttributes();
if ( style != null ) {
String existingStyle = (String) attributes.get( "style" );
if ( existingStyle == null || "".equals( existingStyle ) ) {
attributes.put( "style", style );
} else if ( !existingStyle.contains( style )){
attributes.put( "style", existingStyle + " " + style );
}
}
if ( styleClass != null ) {
String existingStyleClass = (String) attributes.get( "styleClass" );
if ( existingStyleClass == null || "".equals( existingStyleClass ) ) {
attributes.put( "styleClass", styleClass );
} else if ( !existingStyleClass.contains( styleClass )){
attributes.put( "styleClass", existingStyleClass + " " + styleClass );
}
}
}
/**
* Custom implementation of UIViewRoot.createUniqueId. The 'proper' approach
* requires traversing the component tree, which could be expensive. See
* http://java.net/jira/browse/JAVASERVERFACES-2283
*/
public static String createUniqueId() {
FacesContext context = FacesContext.getCurrentInstance();
Map attributes = context.getViewRoot().getAttributes();
Integer uniqueId = (Integer) attributes.get( UNIQUE_ID_VIEW_ATTRIBUTE );
if ( uniqueId == null ) {
uniqueId = 0;
}
attributes.put( UNIQUE_ID_VIEW_ATTRIBUTE, uniqueId + 1 );
// Still use UNIQUE_ID_PREFIX, so that ids are suppressed from the output. As per
// the RenderKit specification:
//
// "If the value returned from component.getId() is non-null and does not start
// with UIViewRoot.UNIQUE_ID_PREFIX, call component.getClientId() and render
// the result as the value of the id attribute in the markup for the component."
return UIViewRoot.UNIQUE_ID_PREFIX + "mw" + uniqueId;
}
//
// Private statics
//
private static void renderChildren( FacesContext context, UIComponent component )
throws IOException {
for ( UIComponent componentChild : component.getChildren() ) {
render( context, componentChild );
}
}
/**
* Match #{...} and ${...}. This mirrors the approach in
* UIComponentTag.isValueReference, but that one is deprecated so may be removed in
* the future.
*/
private static final Pattern PATTERN_EXPRESSION = Pattern.compile( "(#|\\$)\\{([^\\}]+)\\}" );
private static final String EXPRESSION_START = "#{";
private static final String EXPRESSION_END = "}";
private static final String UNIQUE_ID_VIEW_ATTRIBUTE = FacesUtils.class.getName() + ".UNIQUE_ID";
private static final boolean IS_JSF_2;
static {
boolean isJsf2;
try {
Class.forName( "javax.faces.event.PreRenderViewEvent" );
isJsf2 = true;
} catch ( ClassNotFoundException e ) {
isJsf2 = false;
}
IS_JSF_2 = isJsf2;
}
//
// Private constructor
//
private FacesUtils() {
// Can never be called
}
}