ResourceManager


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54  
55  package junitx.util;
56  
57  import java.util.Hashtable  ;
58  import java.util.Map  ;
59  
60  /**
61   * Utility class that manages resources and allows separate tests to share them.
62   *
63   * <h4>Example</h4>
64   *
65   * The AllTests class registers all external resourses by calling the
66   * <tt>addResource</tt> method of the ResourceManager:<p>
67   *
68   * <pre>
69   *    public class AllTests {
70   *
71   *       public static Test suite() {
72   *          TestSuite suite = new TestSuite();
73   *          suite.addTestSuite(MyClassTest.class);
74   *
75   *          return new TestSetup(suite) {
76   *              public void setUp()
77   *                    throws Exception {
78   *                 ResourceManager.addResource("RESOURCE_ID", new Object());
79   *              }
80   *          };
81   *       }
82   *    }
83   * </pre>
84   *
85   * The test class simply gets the resource from the ResourceManager during the
86   * set up process:<p>
87   *
88   * <pre>
89   *    public class MyClassTest extends TestCase {
90   *
91   *       private Object res;
92   *
93   *       public void setUp() {
94   *          res = ResourceManager.getResource("RESOURCE_ID");
95   *       }
96   *
97   *       public void testXYZ() {
98   *          res.XYZ();
99   *       }
100  *    }
101  * </pre>
102  *
103  * To share a resource whithin the same <tt>TestCase</tt>:
104  * 
105  * <pre>
106  *    public class MyClassTest extends TestCase {
107  * 
108  *       private Object res;
109  *
110  *       public void setUp() {
111  *          if (!ResourceManager.contains("RESOURCE_ID")) {
112  *             ResourceManager.addResource("RESOURCE_ID", new Object());
113  *          }
114  *          res = ResourceManager.getResource("RESOURCE_ID");
115  *       }
116  *
117  *       public void testXYZ() {
118  *          res.XYZ();
119  *       }
120  *    }
121  * </pre>
122  *
123  * @version $Revision: 1.4 $ $Date: 2003/03/23 01:25:24 $
124  * @author <a HREF="mailto:vbossica@users.sourceforge.net">Vladimir R. Bossicard</a>
125  */
126 public class ResourceManager {
127 
128     private static Map   resources = new Hashtable  ();
129 
130     /**
131      * Don't let anyone have access to this constructor.
132      */
133     private ResourceManager() {
134     }
135 
136     /**
137      * Associates the resource to the key in the manager. Neither the key nor
138      * the value can be null.  The value can be retrieved by calling the
139      * getResource method with a key that is equal to the original key.
140      *
141      * @param key the resource key.
142      * @param value the resource.
143      * @throws IllegalArgumentException if the key is already used.
144      */
145     public static void addResource(String   key,
146                                    Object   value)
147             throws IllegalArgumentException   {
148         if (resources.containsKey(key)) {
149             throw new IllegalArgumentException  ("Resource with key '" + key + "' already exists");
150         }
151         resources.put(key, value);
152     }
153 
154     /**
155      * Returns the resource to which the specified key is mapped in this
156      * ResourceManager or <tt>null</tt> if the resource was not found.
157      *
158      * @param key a key in the ResourceManager.
159      * @return Object the resource to which the key is mapped in this hashtable.
160      * @throws NullPointerException if the key is null.
161      */
162     public static Object   getResource(String   key)
163             throws NullPointerException   {
164         if (key == null) {
165             throw new NullPointerException  ("Invalid key <null>");
166         }
167         return resources.get(key);
168     }
169 
170     /**
171      * Returns <tt>true</tt> if the ResourceManager contains a resource with
172      * the specified key.
173      */
174     public static boolean containsResource(String   key) {
175         return resources.containsKey(key);
176     }
177     
178     /**
179      * Removes the key (and its corresponding resource) from this
180      * ResourceManager.
181      *
182      * @param key the key that needs to be removed.
183      */
184     public static void removeResource(String   key) {
185         resources.remove(key);
186     }
187 
188 }
189
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