Package org.eclipse.rap.rwt

Class SingletonUtil

java.lang.Object
org.eclipse.rap.rwt.SingletonUtil
public final class SingletonUtil extends Object
Creates and maintains a unique instance of a given type for the given scope. The scope is either a UI session or an application context. Within the context of this scope, getUniqueInstance(...) will always return the same object, but for different scopes the returned instances will be different.

This utility class can be used to adjust classic singletons to the appropriate scope in RAP. Example: 

 public class FooSingleton {

   private FooSingleton() {
   }

   public static FooSingleton getInstance() {
     return SingletonUtil.getUniqueInstance( FooSingleton.class, RWT.getUISession() );
   }
 }
Since:
2.0

  • Constructor Details

    • SingletonUtil

      public SingletonUtil()

  • Method Details

    • getSessionInstance

      public static <T> T getSessionInstance(Class<T> type)
      Returns an instance of the specified type that is unique within the current UI session. If no such instance exists yet, a new one will be created. The specified type must have a parameterless constructor.

      This method is a shortcut for getUniqueInstance( type, RWT.getUISession() ).

      Parameters:
      type - the type to obtain a singleton instance for
      Returns:
      the unique instance of the specified type that is associated with the current UI session

    • getUniqueInstance

      public static <T> T getUniqueInstance(Class<T> type, UISession uiSession)
      Returns an instance of the specified type that is unique within the given UI session. If no such instance exists yet, a new one will be created. The specified type must have a parameterless constructor.
      Parameters:
      type - the type to obtain a singleton instance for
      uiSession - the UI session to store the singleton instance in
      Returns:
      the unique instance of the specified type that is associated with the given UI session
      Since:
      2.3

    • getUniqueInstance

      public static <T> T getUniqueInstance(Class<T> type, ApplicationContext applicationContext)
      Returns an instance of the specified type that is unique within the given UI session. If no such instance exists yet, a new one will be created. The specified type must have a parameterless constructor.
      Parameters:
      type - the type to obtain a singleton instance for
      applicationContext - the application context to store the singleton instance in
      Returns:
      the unique instance of the specified type that is associated with the given application context
      Since:
      2.3