org.eclipse.rap.rwt.SingletonUtil Maven / Gradle / Ivy
/*******************************************************************************
* Copyright (c) 2012 EclipseSource and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* EclipseSource - initial API and implementation
******************************************************************************/
package org.eclipse.rap.rwt;
import org.eclipse.rap.rwt.internal.SingletonManager;
import org.eclipse.rap.rwt.internal.service.ContextProvider;
import org.eclipse.rap.rwt.internal.util.ParamCheck;
import org.eclipse.rap.rwt.service.UISession;
/**
* SingletonUtil creates and manages a unique instance of a given type
* with session scope. This means that in the context of one user session
* getSessionInstance(Class) will always return the same object, but for different user
* sessions the returned instances will be different.
*
* Usage:
*
* public class FooSingleton {
*
* private FooSingleton() {}
*
* public static FooSingleton getInstance() {
* return SingletonUtil.getSessionInstance( FooSingleton.class );
* }
* }
*
*
*
* @since 2.0
*/
public final class SingletonUtil {
/**
* Returns the singleton instance of the specified type that is stored
* in the current session context. If no instance exists yet, a new
* one will be created. The specified type must have a parameterless
* constructor.
*
* @param type specifies the session singleton instance type.
* @return the unique instance of the specified type that is associated
* with the current user session context.
*/
public static T getSessionInstance( Class type ) {
ParamCheck.notNull( type, "type" );
UISession uiSession = ContextProvider.getUISession();
return SingletonManager.getInstance( uiSession ).getSingleton( type );
}
}