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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;
}
}