org.camunda.bpm.engine.rest.impl.FetchAndLockContextListener Maven / Gradle / Ivy
/*
* Copyright Camunda Services GmbH and/or licensed to Camunda Services GmbH
* under one or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information regarding copyright
* ownership. Camunda licenses this file to you under the Apache License,
* Version 2.0; 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.camunda.bpm.engine.rest.impl;
import org.camunda.bpm.engine.rest.exception.RestException;
import org.camunda.bpm.engine.rest.spi.FetchAndLockHandler;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.ws.rs.core.Response;
import java.util.Iterator;
import java.util.ServiceLoader;
/**
* @author Tassilo Weidner
*/
public class FetchAndLockContextListener implements ServletContextListener {
protected static FetchAndLockHandler fetchAndLockHandler;
@Override
public void contextInitialized(ServletContextEvent sce) {
if (fetchAndLockHandler == null) {
fetchAndLockHandler = lookupFetchAndLockHandler();
fetchAndLockHandler.contextInitialized(sce);
fetchAndLockHandler.start();
}
}
@Override
public void contextDestroyed(ServletContextEvent sce) {
fetchAndLockHandler.shutdown();
}
public static FetchAndLockHandler getFetchAndLockHandler() {
return fetchAndLockHandler;
}
protected FetchAndLockHandler lookupFetchAndLockHandler() {
ServiceLoader serviceLoader = ServiceLoader.load(FetchAndLockHandler.class);
Iterator iterator = serviceLoader.iterator();
if(iterator.hasNext()) {
return iterator.next();
} else {
throw new RestException(Response.Status.INTERNAL_SERVER_ERROR,
"Could not find an implementation of the " + FetchAndLockHandler.class.getSimpleName() + "- SPI");
}
}
}