javax.websocket.ContainerProvider Maven / Gradle / Ivy
/*
* Copyright (c) 2018 Oracle and/or its affiliates and others.
* All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0, which is available at
* http://www.eclipse.org/legal/epl-2.0.
*
* This Source Code may also be made available under the following Secondary
* Licenses when the conditions for such availability set forth in the
* Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
* version 2 with the GNU Classpath Exception, which is available at
* https://www.gnu.org/software/classpath/license.html.
*
* SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
*/
package javax.websocket;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Iterator;
import java.util.ServiceLoader;
/**
* Provider class that allows the developer to get a reference to the implementation of the WebSocketContainer. The
* provider class uses the
* ServiceLoader to load an
* implementation of ContainerProvider. Specifically, the fully qualified class name of the container implementation of
* ContainerProvider must be listed in the "META-INF/services/javax.websocket.ContainerProvider" file in the
* implementation JAR file.
*
* @author dannycoward
*/
public abstract class ContainerProvider {
/**
* Obtain a new instance of a WebSocketContainer. The method looks for the ContainerProvider implementation class in
* the order listed in the "META-INF/services/javax.websocket.ContainerProvider" file, returning the first
* WebSocketContainer implementation from the ContainerProvider implementation that is not {@code null}.
*
* @return an implementation provided instance of type WebSocketContainer
*/
public static WebSocketContainer getWebSocketContainer() {
if(System.getSecurityManager() == null) {
return getWebSocketContainerImpl();
} else {
return AccessController.doPrivileged(new PrivilegedAction() {
@Override
public WebSocketContainer run() {
return getWebSocketContainerImpl();
}
});
}
}
private static WebSocketContainer getWebSocketContainerImpl() {
Iterator providers = ServiceLoader.load(ContainerProvider.class).iterator();
if (providers.hasNext()) {
do {
ContainerProvider impl = providers.next();
WebSocketContainer wsc = impl.getContainer();
if (wsc != null) {
return wsc;
}
} while (providers.hasNext());
throw new RuntimeException("Could not find an implementation class with a non-null WebSocketContainer.");
} else {
throw new RuntimeException("Could not find an implementation class.");
}
}
/**
* Create a new instance of the the WebSocket container implementation.
*
* @return the new instance
*/
protected abstract WebSocketContainer getContainer();
}