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1   package org.apache.commons.ognl;
2   
3   /*
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *   http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing,
15   * software distributed under the License is distributed on an
16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17   * KIND, either express or implied.  See the License for the
18   * specific language governing permissions and limitations
19   * under the License.
20   */
21  
22  import java.util.HashMap;
23  import java.util.Map;
24  
25  /**
26   * Default class resolution. Uses ClassLoader.loadClass() to look up classes by name. It also looks in the "java.lang"
27   * package
28   * if the class named does not give a package specifier, allowing easier usage of these classes.
29   *
30   * @author Luke Blanshard (blanshlu@netscape.net)
31   * @author Drew Davidson (drew@ognl.org)
32   */
33  public class DefaultClassResolver
34      implements ClassResolver
35  {
36      private final Map<String, Class<?>> classes = new HashMap<String, Class<?>>( 101 );
37  
38      /**
39       * Resolves a class for a given className
40       *
41       * @param className The name of the Class
42       * @return The resulting Class object
43       * @throws ClassNotFoundException If the class could not be found
44       */
45      public Class<?> classForName( String className )
46          throws ClassNotFoundException
47      {
48          return classForName( className, null );
49      }
50  
51      /**
52       * {@inheritDoc}
53       */
54      public Class<?> classForName( String className, Map<String, Object> unused )
55          throws ClassNotFoundException
56      {
57          Class<?> result = classes.get( className );
58  
59          if ( result == null )
60          {
61              ClassLoader classLoader = ClassLoader.getSystemClassLoader();
62              try
63              {
64                  result = classLoader.loadClass( className );
65              }
66              catch ( ClassNotFoundException ex )
67              {
68                  if ( className.indexOf( '.' ) == -1 )
69                  {
70                      result = classLoader.loadClass( "java.lang." + className );
71                      classes.put( "java.lang." + className, result );
72                  }
73              }
74              classes.put( className, result );
75          }
76          return result;
77      }
78  }