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1   //----------------------------------------------------------------------
2   // 
3   // PerfectJPattern: "Design patterns are good but components are better!" 
4   // Invoker.java Copyright (c) 2009 Giovanni Azua Garcia
5   // bravegag@hotmail.com
6   //  
7   // This program is free software; you can redistribute it and/or
8   // modify it under the terms of the GNU General Public License
9   // as published by the Free Software Foundation; either version 3
10  // of the License, or (at your option) any later version.
11  //
12  // This program is distributed in the hope that it will be useful,
13  // but WITHOUT ANY WARRANTY; without even the implied warranty of
14  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  // GNU General Public License for more details.
16  //
17  // You should have received a copy of the GNU General Public License
18  // along with this program; if not, see <http://www.gnu.org/licenses/>.
19  //
20  //----------------------------------------------------------------------
21  package org.perfectjpattern.core.behavioral.command;
22  
23  import org.apache.commons.lang.*;
24  import org.perfectjpattern.core.api.behavioral.command.*;
25  
26  
27  /**
28   * Base core implementation of <code>IInvoker</code> interface.
29   * <br/>
30   * 
31   * @see IInvoker
32   * 
33   * @param <P> Command Parameter context-specific.
34   * @param <R> Command Result context-specific.
35   *
36   * @author <a href="mailto:bravegag@hotmail.com">Giovanni Azua</a>
37   * @version $Revision: 1.0 $ $Date: Jun 23, 2007 2:34:57 AM $
38   */
39  public
40  class Invoker<P, R>
41  implements IInvoker<P, R> 
42  {
43      //------------------------------------------------------------------------
44      // public
45      //------------------------------------------------------------------------
46      /** 
47       * {@inheritDoc}
48       */
49      public R
50      getResult() 
51      throws IllegalStateException
52      {
53          if (theCommand == null)
54          {
55              throw new IllegalStateException("ICommand was not set.");
56          }
57  
58          R myResult = theCommand.getResult();
59          if (myResult == null)
60          {
61              throw new IllegalStateException("No result available.");
62          }
63  
64          return myResult;
65      }
66  
67      //------------------------------------------------------------------------
68      /** 
69       * {@inheritDoc}
70       */
71      public void 
72      invoke() 
73      throws IllegalStateException    
74      {
75          if (theCommand == null)
76          {
77              throw new IllegalStateException("ICommand was not set.");
78          }
79          
80          if (theParameter != null)
81          {
82              theCommand.setParameter(theParameter);
83          }
84          
85          theCommand.execute();
86      }
87  
88      //------------------------------------------------------------------------
89      /** 
90       * {@inheritDoc}
91       */
92      public void 
93      setCommand(ICommand<P, R> aCommand) 
94      {
95          theCommand = aCommand;
96      }
97  
98      //------------------------------------------------------------------------
99      /** 
100      * {@inheritDoc}
101      */
102     public void 
103     setParameter(P aParameter) 
104     throws IllegalArgumentException
105     {
106         Validate.notNull(aParameter, "'aParameter' must not be null");
107         
108         theParameter = aParameter;
109     }
110     
111     //------------------------------------------------------------------------
112     // members
113     //------------------------------------------------------------------------
114     /**
115      * The <code>ICommand</code> instance.
116      */
117     private ICommand<P, R> theCommand;
118 
119     /**
120      * The <code>IParameter</code> instance.
121      */
122     private P theParameter;
123 }