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1   /*
2    * JBoss, Home of Professional Open Source
3    * Copyright 2014, Red Hat, Inc. and/or its affiliates, and individual
4    * contributors by the @authors tag. See the copyright.txt in the
5    * distribution for a full listing of individual contributors.
6    *
7    * Licensed under the Apache License, Version 2.0 (the "License");
8    * you may not use this file except in compliance with the License.
9    * You may obtain a copy of the License at
10   * http://www.apache.org/licenses/LICENSE-2.0
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.jboss.as.quickstarts.tasksJsf;
18  
19  import java.util.List;
20  
21  import javax.enterprise.context.RequestScoped;
22  import javax.inject.Inject;
23  import javax.inject.Named;
24  
25  
26  /**
27   * <p>
28   * Operations with cached list of tasks for current user.
29   * </p>
30   *
31   * <p>
32   * Delegates to {@link TaskDao} for persistence operations.
33   * </p>
34   *
35   * <p>
36   * This bean ensures that task list will be obtained at most once per request or additionally after each invalidation (
37   * {@link #invalidate()}).
38   * </p>
39   *
40   * <p>
41   * This behavior prevents unnecessary delegations to the persistence layer, since {{@link #getAll()} can be called several times
42   * per request when used in view layer.
43   * </p>
44   *
45   * @author Lukas Fryc
46   */
47  @Named("taskList")
48  @RequestScoped
49  public class TaskListBean implements TaskList {
50  
51      private List<Task> tasks;
52  
53      @Inject
54      private TaskDao taskDao;
55  
56      @Inject
57      @CurrentUser
58      private User currentUser;
59  
60      @Override
61      public List<Task> getAll() {
62          if (tasks == null) {
63              tasks = taskDao.getAll(currentUser);
64          }
65          return tasks;
66      }
67  
68      @Override
69      public void invalidate() {
70          tasks = null;
71      }
72  }