InjectorHolder.java

/**
 * Copyright OPS4J
 *
 * 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.ops4j.pax.wicket.api;

import java.util.HashMap;
import java.util.Map;

import org.apache.wicket.Application;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * A simple singleton class storing and retrieving {@link org.ops4j.pax.wicket.api.PaxWicketInjector}s. The {@link #getInjector()} method only
 * works in an PaxWicket-Enabled integration context.
 *
 * @author nmw
 * @version $Id: $Id
 */
public final class InjectorHolder {
    private static final Logger LOGGER = LoggerFactory.getLogger(InjectorHolder.class);
    private static final InjectorHolder instance = new InjectorHolder();

    private Map<String, PaxWicketInjector> injectorMap = new HashMap<String, PaxWicketInjector>();

    private InjectorHolder() {
    }

    /**
     * Retrieves the InjectionHolder responsible for the active {@link org.apache.wicket.Application}. Therefore this will only work in an
     * active Wicket context!
     *
     * @return Injector
     */
    public static PaxWicketInjector getInjector() {
        String applicationName = Application.get().getApplicationKey();
        PaxWicketInjector injector = null;
        synchronized (instance.injectorMap) {
            injector = instance.injectorMap.get(applicationName);
        }
        if (injector == null) {
            throw new IllegalStateException(String.format("No Injector is set for application %s",
                Application.get().getApplicationKey()));
        }
        return injector;
    }

    /**
     * <p>setInjector.</p>
     *
     * @param applicationName a {@link java.lang.String} object.
     * @param newInjector a {@link org.ops4j.pax.wicket.api.PaxWicketInjector} object.
     */
    public static void setInjector(String applicationName, PaxWicketInjector newInjector) {
        synchronized (instance.injectorMap) {
            instance.injectorMap.put(applicationName, newInjector);
        }
        LOGGER.debug("registered Injector for application {}", applicationName);
    }

}