1 /**
2 * This file Copyright (c) 2011 Magnolia International
3 * Ltd. (http://www.magnolia-cms.com). All rights reserved.
4 *
5 *
6 * This file is dual-licensed under both the Magnolia
7 * Network Agreement and the GNU General Public License.
8 * You may elect to use one or the other of these licenses.
9 *
10 * This file is distributed in the hope that it will be
11 * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
12 * implied warranty of MERCHANTABILITY or FITNESS FOR A
13 * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
14 * Redistribution, except as permitted by whichever of the GPL
15 * or MNA you select, is prohibited.
16 *
17 * 1. For the GPL license (GPL), you can redistribute and/or
18 * modify this file under the terms of the GNU General
19 * Public License, Version 3, as published by the Free Software
20 * Foundation. You should have received a copy of the GNU
21 * General Public License, Version 3 along with this program;
22 * if not, write to the Free Software Foundation, Inc., 51
23 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
24 *
25 * 2. For the Magnolia Network Agreement (MNA), this file
26 * and the accompanying materials are made available under the
27 * terms of the MNA which accompanies this distribution, and
28 * is available at http://www.magnolia-cms.com/mna.html
29 *
30 * Any modifications to this file must keep this entire header
31 * intact.
32 *
33 */
34 package info.magnolia.module;
35
36 import com.google.inject.ProvisionException;
37
38 import javax.inject.Inject;
39 import javax.inject.Provider;
40
41 /**
42 * Provider for the module instance of a module.
43 *
44 * @param <T> the type of the module class
45 * @version $Id$
46 */
47 public class ModuleInstanceProvider<T> implements Provider<T> {
48
49 @Inject
50 private ModuleRegistry moduleRegistry;
51 public String moduleName;
52
53 public ModuleInstanceProvider(String moduleName) {
54 this.moduleName = moduleName;
55 }
56
57 @Override
58 @SuppressWarnings("unchecked")
59 public synchronized T get() {
60 T moduleInstance = (T) moduleRegistry.getModuleInstance(moduleName);
61 if (moduleInstance == null) {
62 throw new ProvisionException(
63 "Module instance for module [" + moduleName + "] not available, most likely because the module has not yet been started. " +
64 "Inject a Provider<> instead to get access to the module instance when it's available.");
65 }
66 return moduleInstance;
67 }
68 }