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/*
 * Copyright (c) 1997, 2018 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 javax.faces.view;

import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Optional;
import java.util.stream.Collectors;

import javax.faces.component.UIComponent;
import javax.faces.component.UIImportConstants;
import javax.faces.component.UIViewAction;
import javax.faces.component.UIViewParameter;
import javax.faces.component.UIViewRoot;
import javax.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)); } }




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