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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
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.apache.commons.discovery.jdk;
18  
19  import java.util.Enumeration;
20  import java.io.IOException;
21  
22  
23  /***
24   * @author Richard A. Sitze
25   */
26  public abstract class JDKHooks {
27      private static final JDKHooks jdkHooks;
28      
29      static {
30          jdkHooks = new JDK12Hooks();
31      }
32      
33      protected JDKHooks() { }
34      
35      /***
36       * Return singleton object representing JVM hooks/tools.
37       * 
38       * TODO: add logic to detect JDK level.
39       */
40      public static final JDKHooks getJDKHooks() {
41          return jdkHooks;
42      }
43  
44      /***
45       * Get the system property
46       *
47       * @param propName name of the property
48       * @return value of the property
49       */
50      public abstract String getSystemProperty(final String propName);
51  
52      /***
53       * The thread context class loader is available for JDK 1.2
54       * or later, if certain security conditions are met.
55       * 
56       * @return The thread context class loader, if available.
57       *         Otherwise return null.
58       */
59      public abstract ClassLoader getThreadContextClassLoader();
60  
61      /***
62       * The system class loader is available for JDK 1.2
63       * or later, if certain security conditions are met.
64       * 
65       * @return The system class loader, if available.
66       *         Otherwise return null.
67       */
68      public abstract ClassLoader getSystemClassLoader();
69      
70      public abstract Enumeration getResources(ClassLoader loader,
71                                               String resourceName)
72          throws IOException;
73  }