jakarta.faces.view.ViewMetadata Maven / Gradle / Ivy
/*
* Copyright (c) 1997, 2020 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0, which is available at
* http://www.eclipse.org/legal/epl-2.0.
*
* This Source Code may also be made available under the following Secondary
* Licenses when the conditions for such availability set forth in the
* Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
* version 2 with the GNU Classpath Exception, which is available at
* https://www.gnu.org/software/classpath/license.html.
*
* SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
*/
package jakarta.faces.view;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Optional;
import java.util.stream.Collectors;
import jakarta.faces.component.UIComponent;
import jakarta.faces.component.UIImportConstants;
import jakarta.faces.component.UIViewAction;
import jakarta.faces.component.UIViewParameter;
import jakarta.faces.component.UIViewRoot;
import jakarta.faces.context.FacesContext;
/**
*
* ViewMetadata is reponsible for extracting and providing view parameter metadata from VDL views. Because
* {@link ViewDeclarationLanguage#getViewMetadata} is required to return null for Jakarta Server Pages
* views and non-null for views authored in Facelets for Jakarta Server Faces 2, this specification only
* applies to Facelets for Jakarta Server Faces 2.
*
*
* @since 2.0
*/
public abstract class ViewMetadata {
/**
*
* Get the view id
*
*
* @return the view ID for which this ViewMetadata instance was created
*/
public abstract String getViewId();
/**
*
* Creates a new {@link UIViewRoot} containing only view parameter metadata. The processing of building this
* UIViewRoot with metadata should not cause any events to be published to the application. The
* implementation must call {@link FacesContext#setProcessingEvents} passing false as the argument, at the
* beginning of the method, and pass true to the same method at the end. The implementation must ensure
* that this happens regardless of ant exceptions that may be thrown.
*
*
*
* Take note a compliant implementation has to ensure that:
*
*
* - the new UIViewRoot must be set as the FacesContext's viewRoot before applying the tag handlers, restoring the old
* FacesContext in a finally block.
* - The contents of the current UIViewRoot's ViewMap must be copied to the ViewMap of the new UIViewRoot before
* applying the tag handlers.
* - The {@link UIImportConstants} must be processed after applying the tag handlers.
*
*
* @param context the {@link FacesContext} for the current request
* @return a UIViewRoot containing only view parameter metadata (if any)
*/
public abstract UIViewRoot createMetadataView(FacesContext context);
/**
*
* Utility method to extract view metadata from the provided {@link UIViewRoot}.
*
*
* @param root the {@link UIViewRoot} from which the metadata will be extracted.
*
* @return a Collection of {@link UIViewParameter} instances. If the view has no metadata, the collection
* will be empty.
*/
public static Collection getViewParameters(UIViewRoot root) {
return getMetadataChildren(root, UIViewParameter.class);
}
/**
*
* Utility method to extract view metadata from the provided {@link UIViewRoot}.
*
*
* @param root the {@link UIViewRoot} from which the metadata will be extracted.
*
* @return a Collection of {@link UIViewAction} instances. If the view has no metadata, the collection will
* be empty.
*/
public static Collection getViewActions(UIViewRoot root) {
return getMetadataChildren(root, UIViewAction.class);
}
/**
*
* Utility method to extract view metadata from the provided {@link UIViewRoot}.
*
*
* @param root The {@link UIViewRoot} from which the metadata will be extracted.
*
* @return A Collection of {@link UIImportConstants} instances. If the view has no metadata, the collection
* will be empty.
*/
public static Collection getImportConstants(UIViewRoot root) {
return getMetadataChildren(root, UIImportConstants.class);
}
/**
*
* Utility method to determine if the the provided {@link UIViewRoot} has metadata. The default implementation will
* return true if the provided {@code UIViewRoot} has a facet named {@link UIViewRoot#METADATA_FACET_NAME} and that
* facet has children. It will return false otherwise.
*
*
* @param root the {@link UIViewRoot} from which the metadata will be extracted from
*
* @return true if the view has metadata, false otherwise.
*/
public static boolean hasMetadata(UIViewRoot root) {
return getMetadataFacet(root).map(m -> m.getChildCount() > 0).orElse(false);
}
@SuppressWarnings("unchecked")
private static List getMetadataChildren(UIViewRoot root, Class type) {
return (List) getMetadataFacet(root).map(m -> m.getChildren()).orElseGet(Collections::emptyList).stream().filter(c -> type.isInstance(c))
.collect(Collectors.toList());
}
private static Optional getMetadataFacet(UIViewRoot root) {
return Optional.ofNullable(root.getFacet(UIViewRoot.METADATA_FACET_NAME));
}
}