IServiceProvider


1   /*******************************************************************************
2    * Copyright (c) 2005 IBM Corporation and others.
3    * All rights reserved. This program and the accompanying materials
4    * are made available under the terms of the Eclipse Public License v1.0
5    * which accompanies this distribution, and is available at
6    * http://www.eclipse.org/legal/epl-v10.html
7    *
8    * Contributors:
9    *     IBM Corporation - initial API and implementation
10   *******************************************************************************/
11  package org.eclipse.ui.internal.components.framework;
12  
13  
14  /**
15   * An <code>IServiceProvider</code> returns services given identifying keys. 
16   * Most service providers will lazily each service the first time it is requested,
17   * and will return the same instance thereafter. Component factories will typically use a 
18   * service provider to locate the dependencies for a component when it is first
19   * created, and the component itself will usually not need to use the service provider
20   * once it is constructed.
21   * 
22   * <p>
23   * Not intended to be implemented by clients.
24   * </p>
25   * 
26   * <p>EXPERIMENTAL: The components framework is currently under active development. All
27   * aspects of this class including its existence, name, and public interface are likely
28   * to change during the development of Eclipse 3.1</p>
29   * 
30   * @since 3.1
31   */
32  public interface IServiceProvider {
33      /**
34       * Returns a component for the given key. Returns null if the given key is not known.
35       * Components returned by this method are managed by the component provider. The
36       * caller does not need to dispose it when done.  
37       *
38       * @param key identifier for the service
39       * @return a component that is assignable to the given type, such that 
40       *         toQuery.isAssignable(container.getComponent(toQuery)).
41       * @throws ComponentException if unable to create the component
42       */
43      Object   getService(Object   key) throws ComponentException;
44  
45      /**
46       * Returns true iff this component provider recognises the given key. If this method
47       * returns true, then getComponent(...) will not return null when given the same
48       * key.
49       * 
50       * @param key identifier for the service
51       * @return true iff this provider contains the given service
52       */
53      boolean hasService(Object   key);
54  }
55
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