restoreviewphase.java

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/*
 * Copyright 2002-2004 the original author or authors.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package de.mindmatters.faces.lifecycle;

import java.util.Iterator;
import java.util.Locale;

import javax.faces.FacesException;
import javax.faces.application.ViewHandler;
import javax.faces.component.UIComponent;
import javax.faces.component.UIInput;
import javax.faces.component.UIViewRoot;
import javax.faces.context.ExternalContext;
import javax.faces.context.FacesContext;
import javax.faces.el.ValueBinding;
import javax.faces.event.PhaseId;

import de.mindmatters.faces.FacesUtils;
import de.mindmatters.faces.application.ViewBuilder;

/**
 * Implements the default <em>Restore View</em> phase of the faces lifecycle.
 * 
 * @author Andreas Kuhrwahl
 */
public class RestoreViewPhase extends AbstractPhase {

    /**
     * Represents the view-id of the view the incoming request was submitted
     * from.
     * <p>
     * Checks whether the view-id was derived from a request parameter or from
     * the request path.
     * </p>
     * 
     * @author Andreas Kuhrwahl
     */
    private class ViewId {

        /** View-id from request parameter or not? */
        private final boolean requestParameter;

        /** The view-id - used for view creation. */
        private final String viewId;

        /**
         * Constructor.
         * 
         * @param requestParameter
         *            view id derived from request paramter or not?
         * @param viewId
         *            the derived view id
         */
        public ViewId(final boolean requestParameter, final String viewId) {
            super();
            this.requestParameter = requestParameter;
            this.viewId = viewId;
        }

        /**
         * @return <code>true</code> if the view-id was derived from a request
         *         parameter <code>false</code> otherwise
         */
        public boolean isRequestParameter() {
            return requestParameter;
        }

        /**
         * @return the derived view id
         */
        public String get() {
            return viewId;
        }

        /**
         * {@inheritDoc}
         */
        public String toString() {
            return this.viewId;
        }

    }

    /**
     * @param context
     *            {@link FacesContext} for the current request
     * @return the derived {@link ViewId}
     */
    private ViewId deriveViewId(final FacesContext context) {
        ExternalContext externalContext = context.getExternalContext();
        boolean isRequestParameter = true;
        String viewId = FacesUtils.decodeViewId(context);
        if (viewId == null) {
            isRequestParameter = false;
            viewId = externalContext.getRequestPathInfo();
            if (viewId == null) {
                viewId = externalContext.getRequestServletPath();
                if (viewId != null) {
                    int dot = viewId.lastIndexOf('.');
                    if (dot != -1) {
                        viewId = viewId.substring(0, dot)
                                + FacesUtils.getDefaultSuffix(context);
                    }
                }
            }
        }
        return new ViewId(isRequestParameter, viewId);
    }

    /**
     * {@inheritDoc}
     */
    public final PhaseId getId() {
        return PhaseId.RESTORE_VIEW;
    }

    /**
     * {@inheritDoc}
     */
    protected final void executePhase(final FacesContext context) {
        if (context == null) {
            throw new FacesException("FacesContext");
        }
        UIViewRoot viewRoot = context.getViewRoot();
        if (viewRoot != null) {
            Locale locale = context.getExternalContext().getRequestLocale();
            context.getViewRoot().setLocale(locale);
            executePerComponentActions(context, viewRoot);
        } else {
            ViewId viewId = deriveViewId(context);
            if (viewId.get() == null) {
                throw new FacesException("ViewId not derived");
            }
            ViewHandler viewHandler = context.getApplication().getViewHandler();
            boolean isViewBuilder = viewHandler instanceof ViewBuilder;
            viewRoot = restoreView(context, viewHandler, viewId.get());
            if (viewRoot == null && viewId.isRequestParameter()
                    && isViewBuilder) {
                viewRoot = buildView(context, (ViewBuilder) viewHandler, viewId
                        .get());
            }
            if (viewRoot == null) {
                viewRoot = createView(context, viewHandler, viewId.get());
            }
            context.setViewRoot(viewRoot);
            if (!isViewBuilder) {
                executePerComponentActions(context, viewRoot);
            }

        }
    }

    /**
     * Perform whatever actions are required to restore the view associated with
     * the specified {@link FacesContext} and <code>viewId</code>. Default
     * implementation delegates to
     * {@link ViewHandler#restoreView(FacesContext, String)}.
     * 
     * @param context
     *            {@link FacesContext} for the current request
     * @param viewHandler
     *            {@link ViewHandler} for the current request
     * @param viewId
     *            the view identifier for the current request
     * @return the restored view
     * @throws FacesException
     *             in case of errors
     */
    protected UIViewRoot restoreView(final FacesContext context,
            final ViewHandler viewHandler, final String viewId) {
        return viewHandler.restoreView(context, viewId);
    }

    /**
     * Perform whatever actions are required to build the view associated with
     * the specified {@link FacesContext} and <code>viewId</code>. Default
     * implementation delegates to
     * {@link ViewBuilder#buildView(FacesContext, String)}.
     * 
     * @param context
     *            {@link FacesContext} for the current request
     * @param viewBuilder
     *            {@link ViewBuilder} for the current request
     * @param viewId
     *            the view identifier for the current request
     * @return the built view
     * @throws FacesException
     *             in case of errors
     */
    protected UIViewRoot buildView(final FacesContext context,
            final ViewBuilder viewBuilder, final String viewId) {
        return viewBuilder.buildView(context, viewId);
    }

    /**
     * Perform whatever actions are required to create the view associated with
     * the specified {@link FacesContext} and <code>viewId</code>. Default
     * implementation delegates to
     * {@link ViewBuilder#createView(FacesContext, String)}.
     * 
     * @param context
     *            {@link FacesContext} for the current request
     * @param viewHandler
     *            {@link ViewHandler} for the current request
     * @param viewId
     *            the view identifier for the current request
     * @return the built view
     * @throws FacesException
     *             in case of errors
     */
    protected UIViewRoot createView(final FacesContext context,
            final ViewHandler viewHandler, final String viewId) {
        UIViewRoot viewRoot = viewHandler.createView(context, viewId);
        context.renderResponse();
        return viewRoot;
    }

    /**
     * Do any per-component actions necessary during reconstitute.
     * 
     * @param context
     *            {@link FacesContext} for the current request
     * @param component
     *            the component the actions will be applied to
     * @throws FacesException
     *             in case of errors
     */
    private void executePerComponentActions(final FacesContext context,
            final UIComponent component) {
        Iterator kids = component.getFacetsAndChildren();
        while (kids.hasNext()) {
            executePerComponentActions(context, (UIComponent) kids.next());
        }
        doPerComponentActions(context, component);
    }

    /**
     * Do any per-component actions necessary during reconstitute.
     * 
     * @param context
     *            {@link FacesContext} for the current request
     * @param component
     *            the component the actions will be applied to
     * @throws FacesException
     *             in case of errors
     */
    protected void doPerComponentActions(final FacesContext context,
            final UIComponent component) {
        ValueBinding valueBinding = component.getValueBinding("binding");
        if (valueBinding != null) {
            valueBinding.setValue(context, component);
        }
        if (component instanceof UIInput) {
            ((UIInput) component).setValid(true);
        }
    }

}