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package javax.faces.view;
import java.util.Collection;
import java.util.Collections;
import java.util.ArrayList;
import java.util.List;
import javax.faces.component.UIViewParameter;
import javax.faces.component.UIViewRoot;
import javax.faces.component.UIComponent;
import javax.faces.component.UIViewAction;
import javax.faces.context.FacesContext;
/**
* <p class="changed_added_2_0"/> <code>ViewMetadata</code> is
* reponsible for extracting and providing view parameter metadata from
* VDL views. Because {@link ViewDeclarationLanguage#getViewMetadata}
* is required to return <code>null</code> for JSP views and
* non-<code>null</code> for views authored in Facelets for JSF 2, this
* specification only applys to Facelets for JSF 2. </p>
*
* @since 2.0
*/
public abstract class ViewMetadata {
/**
* <p class="changed_added_2_0"/>
* @return the view ID for which this <code>ViewMetadata</code> instance
* was created
*/
public abstract String getViewId();
/**
* <p class="changed_added_2_0"> Creates a new {@link UIViewRoot}
* containing only view parameter metadata. The processing of
* building this <code>UIViewRoot</code> with metadata should not
* cause any events to be published to the application. The
* implementation must call {@link FacesContext#setProcessingEvents}
* passing <code>false</code> as the argument, at the beginning of
* the method, and pass <code>true</code> to the same method at the
* end. The implementation must ensure that this happens regardless
* of ant exceptions that may be thrown.</p>
*
* @param context the {@link FacesContext} for the current request
* @return a <code>UIViewRoot</code> containing only view parameter metadata
* (if any)
*/
public abstract UIViewRoot createMetadataView(FacesContext context);
/**
* <p class="changed_added_2_0"> Utility method to extract view
* metadata from the provided {@link UIViewRoot}. </p>
*
* @param root the {@link UIViewRoot} from which the metadata will
* be extracted.
*
* @return a <code>Collection</code> of {@link UIViewParameter}
* instances. If the view has no metadata, the collection will be
* empty.
*/
public static Collection<UIViewParameter> getViewParameters(UIViewRoot root) {
Collection<UIViewParameter> params;
UIComponent metadataFacet = root.getFacet(UIViewRoot.METADATA_FACET_NAME);
if (metadataFacet == null) {
params = Collections.emptyList();
} else {
params = new ArrayList<UIViewParameter>();
List<UIComponent> children = metadataFacet.getChildren();
int len = children.size();
for (int i = 0; i < len; i++) {
UIComponent c = children.get(i);
if (c instanceof UIViewParameter) {
params.add((UIViewParameter) c);
}
}
}
return params;
}
/**
* <p class="changed_added_2_2"> Utility method to extract view
* metadata from the provided {@link UIViewRoot}. </p>
*
* @param root the {@link UIViewRoot} from which the metadata will
* be extracted.
*
* @return a <code>Collection</code> of {@link UIViewAction}
* instances. If the view has no metadata, the collection will be
* empty.
*/
public static Collection<UIViewAction> getViewActions(UIViewRoot root) {
Collection<UIViewAction> actions;
UIComponent metadataFacet = root.getFacet(UIViewRoot.METADATA_FACET_NAME);
if (metadataFacet == null) {
actions = Collections.emptyList();
} else {
actions = new ArrayList<UIViewAction>();
List<UIComponent> children = metadataFacet.getChildren();
int len = children.size();
for (int i = 0; i < len; i++) {
UIComponent c = children.get(i);
if (c instanceof UIViewAction) {
actions.add((UIViewAction) c);
}
}
}
return actions;
}
/**
* <p class="changed_added_2_2">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.</p>
*
* @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) {
boolean result = false;
UIComponent metadataFacet = root.getFacet(UIViewRoot.METADATA_FACET_NAME);
if (null != metadataFacet) {
result = 0 < metadataFacet.getChildCount();
}
return result;
}
}