phase.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 javax.faces.context.FacesContext;
import javax.faces.event.PhaseId;

import org.springframework.util.Assert;

/**
 * A <strong>Phase</strong> is a single step in the processing of a JavaServer
 * Faces request throughout its entire {@link javax.faces.lifecycle.Lifecycle}.
 * Each <code>Phase</code> performs the required transitions on the state
 * information in the {@link FacesContext} associated with this request.
 * 
 * @author Andreas Kuhrwahl
 * @see LifecycleImpl#execute(FacesContext)
 * @see LifecycleImpl#render(FacesContext)
 */
public interface Phase {

    /**
     * Static class that converts a {@link PhaseId} into a readable form. The
     * following table shows the conversions:
     * 
     * <table class="javaDoc">
     * <tr>
     * <th>PhaseId</th>
     * <th>human readable string</th>
     * </tr>
     * <tr>
     * <td>{@link PhaseId#RESTORE_VIEW}</td>
     * <td>RESTORE_VIEW</td>
     * </tr>
     * <tr>
     * <td>{@link PhaseId#APPLY_REQUEST_VALUES}</td>
     * <td>APPLY_REQUEST_VALUES</td>
     * </tr>
     * <tr>
     * <td>{@link PhaseId#PROCESS_VALIDATIONS}</td>
     * <td>PROCESS_VALIDATIONS</td>
     * </tr>
     * <tr>
     * <td>{@link PhaseId#UPDATE_MODEL_VALUES}</td>
     * <td>UPDATE_MODEL_VALUES</td>
     * </tr>
     * <tr>
     * <td>{@link PhaseId#INVOKE_APPLICATION}</td>
     * <td>INVOKE_APPLICATION</td>
     * </tr>
     * <tr>
     * <td>{@link PhaseId#RENDER_RESPONSE}</td>
     * <td>RENDER_RESPONSE</td>
     * </tr>
     * </table>
     * <p>
     * </p>
     * 
     * @author Andreas Kuhrwahl
     * @see PhaseId
     */
    public static final class PhaseIdName {

        /** The string based values of each known {@link PhaseId}. */
        private static final String RESTORE_VIEW = "RESTORE_VIEW",
                APPLY_REQUEST_VALUES = "APPLY_REQUEST_VALUES",
                PROCESS_VALIDATIONS = "PROCESS_VALIDATIONS",
                UPDATE_MODEL_VALUES = "UPDATE_MODEL_VALUES",
                INVOKE_APPLICATION = "INVOKE_APPLICATION",
                RENDER_RESPONSE = "RENDER_RESPONSE";

        /**
         * Private Constructor - it's a static class.
         */
        private PhaseIdName() {
            super();
        }

        /**
         * Converts the given <code>phaseId</code> into a human readable
         * string.
         * 
         * @param phaseId
         *            phase identifier
         * @return the human readable representation of a {@link PhaseId}
         */
        public static String valueOf(final PhaseId phaseId) {
            Assert.notNull(phaseId);
            String name = null;
            if (phaseId.toString().startsWith(RESTORE_VIEW)) {
                name = RESTORE_VIEW;
            } else if (phaseId.toString().startsWith(APPLY_REQUEST_VALUES)) {
                name = APPLY_REQUEST_VALUES;
            } else if (phaseId.toString().startsWith(PROCESS_VALIDATIONS)) {
                name = PROCESS_VALIDATIONS;
            } else if (phaseId.toString().startsWith(UPDATE_MODEL_VALUES)) {
                name = UPDATE_MODEL_VALUES;
            } else if (phaseId.toString().startsWith(INVOKE_APPLICATION)) {
                name = INVOKE_APPLICATION;
            } else if (phaseId.toString().startsWith(RENDER_RESPONSE)) {
                name = RENDER_RESPONSE;
            }
            return name;
        }
    }

    /**
     * Perform all state transitions required by the current phase of the
     * request processing {@link javax.faces.lifecycle.Lifecycle} for a
     * particular request.
     * 
     * @param context
     *            FacesContext for the current request being processed
     * @throws javax.faces.FacesException
     *             if a processing error occurred while executing this phase
     */
    void execute(FacesContext context);

    /**
     * Returns the current {@link javax.faces.lifecycle.Lifecycle} <strong>Phase</strong>
     * identifier.
     * 
     * @return phase identifier
     */
    PhaseId getId();

}