com.isotrol.impe3.core.impl.SessionParamsFactory.java Source code

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Here is the source code for com.isotrol.impe3.core.impl.SessionParamsFactory.java

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/**
 * This file is part of Port@l
 * Port@l 3.0 - Portal Engine and Management System
 * Copyright (C) 2010  Isotrol, SA.  http://www.isotrol.com
 *
 * Port@l is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Port@l is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Port@l.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.isotrol.impe3.core.impl;

import java.util.Enumeration;
import java.util.Map;
import java.util.Set;

import javax.servlet.http.HttpSession;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableMap;
import com.isotrol.impe3.api.SessionParams;
import com.isotrol.impe3.core.impl.MapParameters.AbstractImmutable;

/**
 * Factory class for different HTTP session parameters implementations.
 * @author Andres Rodriguez
 */
public final class SessionParamsFactory {
    /** Not instantiable. */
    private SessionParamsFactory() {
        throw new AssertionError();
    }

    private static final Empty EMPTY = new Empty();

    /**
     * Returns an empty collection of cookies.
     */
    public static SessionParams of() {
        return EMPTY;
    }

    /**
     * Returns a collection built from a Servlet HTTP session.
     * @param session Session.
     * @return The requested collection.
     */
    public static SessionParams of(HttpSession session) {
        Preconditions.checkNotNull(session, "The session cannot be null.");
        final ImmutableMap.Builder<String, Object> builder = ImmutableMap.builder();
        @SuppressWarnings("unchecked")
        final Enumeration<String> names = session.getAttributeNames();
        if (names != null) {
            while (names.hasMoreElements()) {
                final String parameter = names.nextElement();
                final Object value = session.getAttribute(parameter);
                if (value != null) {
                    builder.put(parameter, value);
                }
            }
        }
        return new Immutable(builder.build());
    }

    /**
     * Empty HTTP session parameters implementation.
     * @author Andres Rodriguez
     */
    private static final class Empty extends EmptyParameters<Object> implements SessionParams {
        private Empty() {
        }

        public <T> T get(String parameter, Class<T> type) {
            return null;
        }

        public SessionParams subset(Set<String> included) {
            return this;
        }
    }

    /**
     * Immutable HTTP session params implementation.
     * @author Andres Rodriguez
     */
    private static final class Immutable extends AbstractImmutable<Object> implements SessionParams {
        private Immutable(Map<String, Object> parameters) {
            super(parameters);
        }

        /*
         * (non-Javadoc)
         * 
         * @see com.isotrol.impe3.api.SessionParams#get(java.lang.String, java.lang.Class)
         */
        public final <T> T get(String parameter, Class<T> type) {
            Preconditions.checkNotNull(type);
            Object value = get(parameter);
            if (value != null) {
                return type.cast(value);
            }
            return null;
        }

        public SessionParams subset(Set<String> included) {
            return new Immutable(submap(included));
        }
    }
}