1 /*
2 * Copyright 2002-2004 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.commons.clazz;
17
18 import java.util.HashSet;
19
20 /**
21 * Constructs/loads Clazzes.
22 *
23 * @author <a href="mailto:dmitri@apache.org">Dmitri Plotnikov</a>
24 * @version $Id: ClazzLoader.java 155436 2005-02-26 13:17:48Z dirkv $
25 */
26 public abstract class ClazzLoader {
27 private ModelClazzLoader modelClazzLoader;
28
29 /**
30 * ClazzLoaders are grouped into models.
31 */
32 public ClazzLoader(ModelClazzLoader modelClazzLoader) {
33 this.modelClazzLoader = modelClazzLoader;
34 }
35
36 /**
37 * Returns the model clazz loader for this clazz loader.
38 */
39 public ModelClazzLoader getModelClazzLoader() {
40 return modelClazzLoader;
41 }
42
43 /**
44 * Returns the name of the model this clazz loader belongs to.
45 */
46 public String getModel() {
47 return getModelClazzLoader().getModel();
48 }
49
50 /**
51 * Given a Clazz name, returns the corresponding Clazz. Does not
52 * cache clazzes, that's the job of CachingGroupClazzLoader. Return null if
53 * there is no Clazz for this name.
54 * <p>
55 * Note that we use canonical class names for primitive types and arrays,
56 * e.g. "byte", "byte[]", "boolean[][]", "java.lang.String[]".
57 */
58 public abstract Clazz getClazzForName(String name);
59
60 /**
61 * Returns true iff this loader has or can construct a Clazz for the
62 * supplied instance.
63 */
64 public abstract boolean isMember(Object instance);
65
66 /**
67 * Returns the Clazz for the supplied instance. Returns <code>null</code>
68 * if it cannot produce such a Clazz.
69 */
70 public Clazz getClazz(Object instance) {
71 if (instance == null) {
72 return null;
73 }
74
75 String name = getClazzName(instance);
76 if (name == null) {
77 return null;
78 }
79 return getClazzForName(name);
80 }
81
82 /**
83 * Returns the clazz name for the supplied instance. Returns
84 * <code>null</code> if it cannot produce a clazz name for the instance.
85 */
86 public abstract String getClazzName(Object instance);
87
88 /**
89 * Defines a new Clazz with the supplied name. If it cannot define a
90 * clazz of the supplied type or if it cannot define clazzes at all, returns
91 * null.
92 *
93 * @param name the name of the clazz, should be unique within the scope of
94 * the top-level ClazzLoader
95 * @param clazzClass the Class of the Clazz that this method needs to
96 * produce.
97 * @param instanceClass the Class of the instances the new Clazz will be
98 * able to create using the <code>newInstance()</code> method.
99 *
100 * @return Clazz
101 */
102 public abstract Clazz defineClazz(
103 String name,
104 Class clazzClass,
105 Class instanceClass);
106
107 private HashSet loggingEnabledClasses = new HashSet();
108
109 /**
110 * Enable diagnistic logging for the specified class.
111 */
112 public void enableLogging(String className) {
113 loggingEnabledClasses.add(className);
114 }
115
116 public boolean isLoggingEnabled(String className) {
117 return loggingEnabledClasses.contains(className);
118 }
119
120 }