ClassUtils


1   /*
2    * Copyright 1999-2004 The Apache Software Foundation.
3    * 
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    * 
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    * 
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  package org.apache.cocoon.util;
17  
18  import java.io.File  ;
19  import java.io.IOException  ;
20  import java.net.MalformedURLException  ;
21  import java.net.URL  ;
22  
23  /**
24   * A collection of class management utility methods.
25   *
26   * @author <a HREF="mailto:ricardo@apache.org">Ricardo Rocha</a>
27   * @author <a HREF="mailto:stefano@apache.org">Stefano Mazzocchi</a>
28   * @version CVS $Id: ClassUtils.java 56874 2004-11-07 23:09:11Z antonio $
29   */
30  public class ClassUtils {
31  
32      /**
33       * Create a new instance given a class name
34       *
35       * @param className A class name
36       * @return A new instance
37       * @exception Exception If an instantiation error occurs
38       */
39      public static Object   newInstance(String   className) throws Exception   {
40          return ClassUtils.loadClass(className).newInstance();
41      }
42  
43      /**
44       * Load a class given its name.
45       * BL: We wan't to use a known ClassLoader--hopefully the hierarchy
46       *     is set correctly.
47       *
48       * @param className A class name
49       * @return The class pointed to by <code>className</code>
50       * @exception ClassNotFoundException If a loading error occurs
51       */
52      public static Class   loadClass(String   className) throws ClassNotFoundException   {
53          return ClassUtils.getClassLoader().loadClass(className);
54      }
55  
56      /**
57       * Return a resource URL.
58       * BL: if this is command line operation, the classloading issues
59       *     are more sane.  During servlet execution, we explicitly set
60       *     the ClassLoader.
61       *
62       * @return The context classloader.
63       * @exception MalformedURLException If a loading error occurs
64       */
65      public static URL   getResource(String   resource) throws MalformedURLException   {
66          return ClassUtils.getClassLoader().getResource(resource);
67      }
68  
69      /**
70       * Return the context classloader.
71       * BL: if this is command line operation, the classloading issues
72       *     are more sane.  During servlet execution, we explicitly set
73       *     the ClassLoader.
74       *
75       * @return The context classloader.
76       */
77      public static ClassLoader   getClassLoader() {
78          return Thread.currentThread().getContextClassLoader();
79      }
80  
81      /**
82       * Tests if a class implements a given interface
83       *
84       * @return true if class implements given interface.
85       * @deprecated Will be removed 2 versions after 2.1.5
86       */
87      public static boolean implementsInterface(String   className, String   iface) throws Exception   {
88          Class   class1 = ClassUtils.loadClass (className);
89          Class   class2 = ClassUtils.loadClass (iface);
90          return ClassUtils.implementsInterface(class1, class2);
91      }
92  
93      /**
94       * Tests if a class implements a given interface
95       *
96       * @return true if class implements given interface.
97       * @deprecated Will be removed 2 versions after 2.1.5
98       */
99      public static boolean implementsInterface(Class   class1, Class   iface) {
100         return iface.isAssignableFrom (class1);
101     }
102 
103     /**
104      * Determine the last modification date for this
105      * class file or its enclosing library
106      *
107      * @param aClass A class whose last modification date is queried
108      * @return The time the given class was last modified
109      * @exception IOException IOError
110      * @exception IllegalArgumentException The class was not loaded from a file
111      * or directory
112      * @deprecated Will be removed 2 versions after 2.1.5
113      */
114     public static long lastModified(Class   aClass)
115         throws IOException  , IllegalArgumentException    {
116         URL   url = aClass.getProtectionDomain().getCodeSource().getLocation();
117 
118         if (!url.getProtocol().equals("file")) {
119             throw new IllegalArgumentException  ("Class was not loaded from a file url");
120         }
121 
122         File   directory = new File  (url.getFile());
123         if (!directory.isDirectory()) {
124             throw new IllegalArgumentException  ("Class was not loaded from a directory");
125         }
126 
127         String   className = aClass.getName();
128         String   basename = className.substring(className.lastIndexOf(".") + 1);
129 
130         File   file = new File  (directory, basename + ".class");
131 
132         return file.lastModified();
133     }
134 
135     /**
136      * Gets the absolute pathname of the class file
137      * containing the specified class name, as prescribed
138      * by the current classpath.
139      *
140      * @param aClass Name of the class.
141      * @deprecated Will be removed 2 versions after 2.1.5
142      */
143      public static String   which(Class   aClass) {
144         String   path = null;
145         try {
146             path = aClass.getProtectionDomain().getCodeSource().getLocation().toString();
147         } catch (Throwable   t){
148         }
149         return path;
150     }
151 
152 }
153
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