org.directwebremoting.datasync.PerHttpSessionStoreProvider Maven / Gradle / Ivy

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DWR is easy Ajax for Java. It makes it simple to call Java code directly from Javascript. It gets rid of almost all the boiler plate code between the web browser and your Java code.

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/*
 * Copyright 2005 Joe Walker
 *
 * 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 org.directwebremoting.datasync;

import javax.servlet.http.HttpSession;

import org.directwebremoting.WebContextFactory;

/**
 * A StoreProvider that allows us to have a number of StoreProviders for each
 * HttpSession. New {@link StoreProvider}s are created by a
 * {@link StoreProviderFactory} and stored in the HttpSession under a given
 * attribute name.
 * @author Joe Walker [joe at getahead dot ltd dot uk]
 */
public class PerHttpSessionStoreProvider extends AbstractPerXStoreProvider
{
    public PerHttpSessionStoreProvider(StoreProviderFactory factory, String attributeName)
    {
        this.factory = factory;
        this.attributeName = attributeName;
    }

    /**
     * Internal method to find or create a StoreProvider for a given user.
     */
    @Override
    protected StoreProvider getStoreProvider()
    {
        HttpSession session = WebContextFactory.get().getSession(true);

        @SuppressWarnings("unchecked")
        StoreProvider storeProvider = (StoreProvider) session.getAttribute(attributeName);

        if (storeProvider == null)
        {
            storeProvider = factory.create(session);
            session.setAttribute(attributeName, storeProvider);
        }

        return storeProvider;
    }

    /**
     * The attribute name that we are storing created StoreProviders under in
     * the HttpSession
     */
    private final String attributeName;

    /**
     * The factory to enable us to create factories per HttpSession
     */
    private final StoreProviderFactory factory;
}