Java > Open Source Codes > org > apache > commons > logging > pathable > ParentFirstTestCase


1 /*
2  * Copyright 2005 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.logging.pathable;
17
18 import java.net.URL ;
19 import java.util.ArrayList ;
20 import java.util.Arrays ;
21 import java.util.Enumeration ;
22
23 import junit.framework.Test;
24 import junit.framework.TestCase;
25
26 import org.apache.commons.logging.PathableClassLoader;
27 import org.apache.commons.logging.PathableTestSuite;
28
29 /**
30  * Tests for the PathableTestSuite and PathableClassLoader functionality,
31  * where lookup order for the PathableClassLoader is parent-first.
32  * <p>
33  * These tests assume:
34  * <ul>
35  * <li>junit is in system classpath
36  * <li>nothing else is in system classpath
37  * </ul>
38  */
39
40 public class ParentFirstTestCase extends TestCase {
41     
42     /**
43      * Set up a custom classloader hierarchy for this test case.
44      * The hierarchy is:
45      * <ul>
46      * <li> contextloader: parent-first.
47      * <li> childloader: parent-first, used to load test case.
48      * <li> parentloader: parent-first, parent is the bootclassloader.
49      * </ul>
50      */
51     public static Test suite() throws Exception {
52         Class thisClass = ParentFirstTestCase.class;
53         ClassLoader thisClassLoader = thisClass.getClassLoader();
54
55         // Make the parent a direct child of the bootloader to hide all
56 // other classes in the system classpath
57 PathableClassLoader parent = new PathableClassLoader(null);
58         
59         // Make the junit classes visible as a special case, as junit
60 // won't be able to call this class at all without this. The
61 // junit classes must be visible from the classloader that loaded
62 // this class, so use that as the source for future access to classes
63 // from the junit package.
64 parent.useExplicitLoader("junit.", thisClassLoader);
65         
66         // make the commons-logging.jar classes visible via the parent
67 parent.addLogicalLib("commons-logging");
68         
69         // create a child classloader to load the test case through
70 PathableClassLoader child = new PathableClassLoader(parent);
71         
72         // obviously, the child classloader needs to have the test classes
73 // in its path!
74 child.addLogicalLib("testclasses");
75         child.addLogicalLib("commons-logging-adapters");
76         
77         // create a third classloader to be the context classloader.
78 PathableClassLoader context = new PathableClassLoader(child);
79
80         // reload this class via the child classloader
81 Class testClass = child.loadClass(thisClass.getName());
82         
83         // and return our custom TestSuite class
84 return new PathableTestSuite(testClass, context);
85     }
86     
87     /**
88      * Test that the classloader hierarchy is as expected, and that
89      * calling loadClass() on various classloaders works as expected.
90      * Note that for this test case, parent-first classloading is
91      * in effect.
92      */
93     public void testPaths() throws Exception {
94         // the context classloader is not expected to be null
95 ClassLoader contextLoader = Thread.currentThread().getContextClassLoader();
96         assertNotNull("Context classloader is null", contextLoader);
97         assertEquals("Context classloader has unexpected type",
98                 PathableClassLoader.class.getName(),
99                 contextLoader.getClass().getName());
100         
101         // the classloader that loaded this class is obviously not null
102 ClassLoader thisLoader = this.getClass().getClassLoader();
103         assertNotNull("thisLoader is null", thisLoader);
104         assertEquals("thisLoader has unexpected type",
105                 PathableClassLoader.class.getName(),
106                 thisLoader.getClass().getName());
107         
108         // the suite method specified that the context classloader's parent
109 // is the loader that loaded this test case.
110 assertSame("Context classloader is not child of thisLoader",
111                 thisLoader, contextLoader.getParent());
112
113         // thisLoader's parent should be available
114 ClassLoader parentLoader = thisLoader.getParent();
115         assertNotNull("Parent classloader is null", parentLoader);
116         assertEquals("Parent classloader has unexpected type",
117                 PathableClassLoader.class.getName(),
118                 parentLoader.getClass().getName());
119         
120         // parent should have a parent of null
121 assertNull("Parent classloader has non-null parent", parentLoader.getParent());
122
123         // getSystemClassloader is not a PathableClassLoader; it's of a
124 // built-in type. This also verifies that system classloader is none of
125 // (context, child, parent).
126 ClassLoader systemLoader = ClassLoader.getSystemClassLoader();
127         assertNotNull("System classloader is null", systemLoader);
128         assertFalse("System classloader has unexpected type",
129                 PathableClassLoader.class.getName().equals(
130                         systemLoader.getClass().getName()));
131
132         // junit classes should be visible; their classloader is system.
133 // this will of course throw an exception if not found.
134 Class junitTest = contextLoader.loadClass("junit.framework.Test");
135         assertSame("Junit not loaded via systemloader",
136                 systemLoader, junitTest.getClassLoader());
137
138         // jcl api classes should be visible only via the parent
139 Class logClass = contextLoader.loadClass("org.apache.commons.logging.Log");
140         assertSame("Log class not loaded via parent",
141                 logClass.getClassLoader(), parentLoader);
142
143         // jcl adapter classes should be visible via both parent and child. However
144 // as the classloaders are parent-first we should see the parent one.
145 Class log4jClass = contextLoader.loadClass("org.apache.commons.logging.impl.Log4JLogger");
146         assertSame("Log4JLogger not loaded via parent",
147                 log4jClass.getClassLoader(), parentLoader);
148         
149         // test classes should be visible via the child only
150 Class testClass = contextLoader.loadClass("org.apache.commons.logging.PathableTestSuite");
151         assertSame("PathableTestSuite not loaded via child",
152                 testClass.getClassLoader(), thisLoader);
153         
154         // test loading of class that is not available
155 try {
156             Class noSuchClass = contextLoader.loadClass("no.such.class");
157             fail("Class no.such.class is unexpectedly available");
158         } catch(ClassNotFoundException ex) {
159             // ok
160 }
161
162         // String class classloader is null
163 Class stringClass = contextLoader.loadClass("java.lang.String");
164         assertNull("String class classloader is not null!",
165                 stringClass.getClassLoader());
166     }
167     
168     /**
169      * Test that the various flavours of ClassLoader.getResource work as expected.
170      */
171     public void testResource() {
172         URL resource;
173         
174         ClassLoader contextLoader = Thread.currentThread().getContextClassLoader();
175         ClassLoader childLoader = contextLoader.getParent();
176         
177         // getResource where it doesn't exist
178 resource = childLoader.getResource("nosuchfile");
179         assertNull("Non-null URL returned for invalid resource name", resource);
180
181         // getResource where it is accessable only to parent classloader
182 resource = childLoader.getResource("org/apache/commons/logging/Log.class");
183         assertNotNull("Unable to locate Log.class resource", resource);
184         
185         // getResource where it is accessable only to child classloader
186 resource = childLoader.getResource("org/apache/commons/logging/PathableTestSuite.class");
187         assertNotNull("Unable to locate PathableTestSuite.class resource", resource);
188
189         // getResource where it is accessable to both classloaders. The one visible
190 // to the parent should be returned. The URL returned will be of form
191 // jar:file:/x/y.jar!path/to/resource. The filename part should include the jarname
192 // of form commons-logging-nnnn.jar, not commons-logging-adapters-nnnn.jar
193 resource = childLoader.getResource("org/apache/commons/logging/impl/Log4JLogger.class");
194         assertNotNull("Unable to locate Log4JLogger.class resource", resource);
195         assertTrue("Incorrect source for Log4JLogger class",
196                 resource.toString().indexOf("/commons-logging-1.") > 0);
197     }
198     
199     /**
200      * Test that the various flavours of ClassLoader.getResources work as expected.
201      */
202     public void testResources() throws Exception {
203         Enumeration resources;
204         URL [] urls;
205         
206         // verify the classloader hierarchy
207 ClassLoader contextLoader = Thread.currentThread().getContextClassLoader();
208         ClassLoader childLoader = contextLoader.getParent();
209         ClassLoader parentLoader = childLoader.getParent();
210         ClassLoader bootLoader = parentLoader.getParent();
211         assertNull("Unexpected classloader hierarchy", bootLoader);
212         
213         // getResources where no instances exist
214 resources = childLoader.getResources("nosuchfile");
215         urls = toURLArray(resources);
216         assertEquals("Non-null URL returned for invalid resource name", 0, urls.length);
217         
218         // getResources where the resource only exists in the parent
219 resources = childLoader.getResources("org/apache/commons/logging/Log.class");
220         urls = toURLArray(resources);
221         assertEquals("Unexpected number of Log.class resources found", 1, urls.length);
222         
223         // getResources where the resource only exists in the child
224 resources = childLoader.getResources("org/apache/commons/logging/PathableTestSuite.class");
225         urls = toURLArray(resources);
226         assertEquals("Unexpected number of PathableTestSuite.class resources found", 1, urls.length);
227         
228         // getResources where the resource exists in both.
229 // resources should be returned in order (parent-resource, child-resource)
230 resources = childLoader.getResources("org/apache/commons/logging/impl/Log4JLogger.class");
231         urls = toURLArray(resources);
232         assertEquals("Unexpected number of Log4JLogger.class resources found", 2, urls.length);
233         
234         // There is no gaurantee about the ordering of results returned from getResources
235 // To make this test portable across JVMs, sort the string to give them a known order
236 String [] urlsToStrings = new String [2];
237         urlsToStrings[0] = urls[0].toString();
238         urlsToStrings[1] = urls[1].toString();
239         Arrays.sort(urlsToStrings);
240         assertTrue("Incorrect source for Log4JLogger class",
241                 urlsToStrings[0].indexOf("/commons-logging-1.") > 0);
242         assertTrue("Incorrect source for Log4JLogger class",
243                 urlsToStrings[1].indexOf("/commons-logging-adapters-1.") > 0);
244         
245     }
246
247     /**
248      * Utility method to convert an enumeration-of-URLs into an array of URLs.
249      */
250     private static URL [] toURLArray(Enumeration e) {
251         ArrayList l = new ArrayList ();
252         while (e.hasMoreElements()) {
253             URL u = (URL ) e.nextElement();
254             l.add(u);
255         }
256         URL [] tmp = new URL [l.size()];
257         return (URL []) l.toArray(tmp);
258     }
259
260     /**
261      * Test that getResourceAsStream works.
262      */
263     public void testResourceAsStream() throws Exception {
264         java.io.InputStream is;
265         
266         // verify the classloader hierarchy
267 ClassLoader contextLoader = Thread.currentThread().getContextClassLoader();
268         ClassLoader childLoader = contextLoader.getParent();
269         ClassLoader parentLoader = childLoader.getParent();
270         ClassLoader bootLoader = parentLoader.getParent();
271         assertNull("Unexpected classloader hierarchy", bootLoader);
272         
273         // getResourceAsStream where no instances exist
274 is = childLoader.getResourceAsStream("nosuchfile");
275         assertNull("Invalid resource returned non-null stream", is);
276         
277         // getResourceAsStream where resource does exist
278 is = childLoader.getResourceAsStream("org/apache/commons/logging/Log.class");
279         assertNotNull("Null returned for valid resource", is);
280         is.close();
281         
282         // It would be nice to test parent-first ordering here, but that would require
283 // having a resource with the same name in both the parent and child loaders,
284 // but with different contents. That's a little tricky to set up so we'll
285 // skip that for now.
286 }
287 }
288

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