org.atmosphere.di.ServletContextHolder Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of atmosphere-runtime Show documentation

There is a newer version: 3.0.13

/*
 * Copyright 2013 Jeanfrancois Arcand
 *
 * 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.atmosphere.di;

import javax.servlet.ServletContext;
import java.lang.ref.WeakReference;
import java.util.concurrent.atomic.AtomicReference;

/**
 * Holds the reference of an object being able to return the current ServletContext of the web application
 *
 * @author Mathieu Carbou
 * @since 0.7
 */
public final class ServletContextHolder {

    private static AtomicReference> PROVIDER = new AtomicReference>();

    private ServletContextHolder() {
    }

    public static void register(ServletContextProvider provider) {
        PROVIDER.set(new WeakReference(provider));
    }

    public static ServletContext getServletContext() {
        WeakReference ref = PROVIDER.get();
        if (ref != null) {
            ServletContextProvider provider = ref.get();
            if (provider != null) {
                return provider.getServletContext();
            }
        }
        throw new IllegalStateException("No " + ServletContextProvider.class.getSimpleName() + " found.");
    }
}