override getResources in a new AntClassLoader subclass that will be used consistently when Ant is running on Java5+. PR 46752

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@796647 13f79535-47bb-0310-9956-ffa450edef68

WHATSNEW

@@ -789,6 +789,14 @@ Other changes:
    task's (compiler) adapter class.
    Bugzilla Issue 11143.
 
+ * A new subclass org.apache.tools.ant.loader.AntClassLoader5 of
+   AntClassLoader has been added which overrides getResources
+   which became non-final in ClassLoader with Java5+ so
+   this method now behaves as expected.
+   The new subclass will be used by Ant internally if it is available
+   and Ant is running on Java5 or more recent.
+   Bugzilla Issue 46752.
+
 Changes from Ant 1.7.0 TO Ant 1.7.1
 =============================================
 

build.xml

@@ -175,6 +175,7 @@
     <or>
       <filename name="${taskdefs.package}/AptTest*"/>
       <filename name="${util.package}/java15/*"/>
+      <filename name="${ant.package}/loader/*5*"/>
     </or>
   </selector>
 

src/main/org/apache/tools/ant/AntClassLoader.java

@@ -46,6 +46,7 @@ import org.apache.tools.ant.util.CollectionUtils;
 import org.apache.tools.ant.util.FileUtils;
 import org.apache.tools.ant.util.JavaEnvUtils;
 import org.apache.tools.ant.util.LoaderUtils;
+import org.apache.tools.ant.util.ReflectUtil;
 import org.apache.tools.ant.util.VectorSet;
 import org.apache.tools.ant.launch.Locator;
 
@@ -910,6 +911,19 @@ public class AntClassLoader extends ClassLoader implements SubBuildListener {
         return url;
     }
 
+    /**
+     * Finds all the resources with the given name. A resource is some
+     * data (images, audio, text, etc) that can be accessed by class
+     * code in a way that is independent of the location of the code.
+     *
+     * <p>Would override getResources if that wasn't final in Java
+     * 1.4.</p>
+     */
+    public Enumeration/*<URL>*/ getNamedResources(String name)
+        throws IOException {
+        return findResources(name, false);
+    }
+
     /**
      * Returns an enumeration of URLs representing all the resources with the
      * given name by searching the class loader's classpath.
@@ -920,14 +934,34 @@ public class AntClassLoader extends ClassLoader implements SubBuildListener {
      * @exception IOException if I/O errors occurs (can't happen)
      */
     protected Enumeration/*<URL>*/ findResources(String name) throws IOException {
+        return findResources(name, true);
+    }
+
+    /**
+     * Returns an enumeration of URLs representing all the resources with the
+     * given name by searching the class loader's classpath.
+     *
+     * @param name The resource name to search for.
+     *             Must not be <code>null</code>.
+     * @param parentHasBeenSearched whether ClassLoader.this.parent
+     * has been searched - will be true if the method is (indirectly)
+     * called from ClassLoader.getResources
+     * @return an enumeration of URLs for the resources
+     * @exception IOException if I/O errors occurs (can't happen)
+     */
+    protected Enumeration/*<URL>*/ findResources(String name,
+                                                 boolean parentHasBeenSearched)
+        throws IOException {
         Enumeration/*<URL>*/ mine = new ResourceEnumeration(name);
         Enumeration/*<URL>*/ base;
-        if (parent != null && parent != getParent()) {
+        if (parent != null && (!parentHasBeenSearched || parent != getParent())) {
             // Delegate to the parent:
             base = parent.getResources(name);
-            // Note: could cause overlaps in case ClassLoader.this.parent has matches.
+            // Note: could cause overlaps in case
+            // ClassLoader.this.parent has matches and
+            // parentHasBeenSearched is true
         } else {
-            // ClassLoader.this.parent is already delegated to from
+            // ClassLoader.this.parent is already delegated to for example from
             // ClassLoader.getResources, no need:
             base = new CollectionUtils.EmptyEnumeration();
         }
@@ -1456,6 +1490,22 @@ public class AntClassLoader extends ClassLoader implements SubBuildListener {
         return "AntClassLoader[" + getClasspath() + "]";
     }
 
+    private static Class subClassToLoad = null;
+    private static final Class[] CONSTRUCTOR_ARGS = new Class[] {
+        ClassLoader.class, Project.class, Path.class, Boolean.TYPE
+    };
+
+    static {
+        if (JavaEnvUtils.isAtLeastJavaVersion(JavaEnvUtils.JAVA_1_5)) {
+            try {
+                subClassToLoad =
+                    Class.forName("org.apache.tools.ant.loader.AntClassLoader5");
+            } catch (ClassNotFoundException e) {
+                // this is Java5 but the installation is lacking our subclass
+            }
+        }
+    }
+
     /**
      * Factory method
      */
@@ -1463,6 +1513,15 @@ public class AntClassLoader extends ClassLoader implements SubBuildListener {
                                                    Project project,
                                                    Path path,
                                                    boolean parentFirst) {
+        if (subClassToLoad != null) {
+            return (AntClassLoader)
+                ReflectUtil.newInstance(subClassToLoad,
+                                        CONSTRUCTOR_ARGS,
+                                        new Object[] {
+                                            parent, project, path,
+                                            Boolean.valueOf(parentFirst)
+                                        });
+        }
         return new AntClassLoader(parent, project, path, parentFirst);
     }
 

src/main/org/apache/tools/ant/loader/AntClassLoader5.java

@@ -0,0 +1,56 @@
+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one or more
+ *  contributor license agreements.  See the NOTICE file distributed with
+ *  this work for additional information regarding copyright ownership.
+ *  The ASF licenses this file to You under the Apache License, Version 2.0
+ *  (the "License"); you may not use this file except in compliance with
+ *  the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ */
+
+package org.apache.tools.ant.loader;
+
+import java.util.Enumeration;
+import java.io.IOException;
+import org.apache.tools.ant.AntClassLoader;
+import org.apache.tools.ant.Project;
+import org.apache.tools.ant.types.Path;
+
+/**
+ * Overrides getResources which became non-final in Java5
+ */
+public class AntClassLoader5 extends AntClassLoader {
+    /**
+     * Creates a classloader for the given project using the classpath given.
+     *
+     * @param parent The parent classloader to which unsatisfied loading
+     *               attempts are delegated. May be <code>null</code>,
+     *               in which case the classloader which loaded this
+     *               class is used as the parent.
+     * @param project The project to which this classloader is to belong.
+     *                Must not be <code>null</code>.
+     * @param classpath the classpath to use to load the classes.
+     *                  May be <code>null</code>, in which case no path
+     *                  elements are set up to start with.
+     * @param parentFirst If <code>true</code>, indicates that the parent
+     *                    classloader should be consulted  before trying to
+     *                    load the a class through this loader.
+     */
+    public AntClassLoader5(ClassLoader parent, Project project,
+                           Path classpath, boolean parentFirst) {
+        super(parent, project, classpath, parentFirst);
+    }
+
+    /** {@inheritDoc} */
+    public Enumeration getResources(String name) throws IOException {
+        return getNamedResources(name);
+    }
+}

src/main/org/apache/tools/ant/util/ReflectUtil.java

@@ -17,6 +17,7 @@
  */
 package org.apache.tools.ant.util;
 
+import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import org.apache.tools.ant.BuildException;
@@ -35,6 +36,23 @@ public class ReflectUtil {
     private ReflectUtil() {
     }
 
+    /**
+     * Create an instance of a class using the constructor matching
+     * the given arguments.
+     * @since Ant 1.8.0
+     */
+    public static Object newInstance(Class ofClass,
+                                     Class[] argTypes,
+                                     Object[] args) {
+        try {
+            Constructor con = ofClass.getConstructor(argTypes);
+            return con.newInstance(args);
+        } catch (Exception t) {
+            throwBuildException(t);
+            return null; // NotReached
+        }
+    }
+
     /**
      * Call a method on the object with no parameters.
      * @param obj  the object to invoke the method on.

src/tests/junit/org/apache/tools/ant/AntClassLoaderDelegationTest.java

@@ -99,12 +99,7 @@ public class AntClassLoaderDelegationTest extends TestCase {
     }
     
     private static List enum2List(Enumeration e) {
-        // JDK 1.4: return Collections.list(e);
-        List l = new ArrayList();
-        while (e.hasMoreElements()) {
-            l.add(e.nextElement());
-        }
-        return l;
+        return Collections.list(e);
     }
     
     /** Special loader that just knows how to find TEST_RESOURCE. */

src/tests/junit/org/apache/tools/ant/loader/AntClassLoader5Test.java

@@ -0,0 +1,65 @@
+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one or more
+ *  contributor license agreements.  See the NOTICE file distributed with
+ *  this work for additional information regarding copyright ownership.
+ *  The ASF licenses this file to You under the Apache License, Version 2.0
+ *  (the "License"); you may not use this file except in compliance with
+ *  the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ */
+
+package org.apache.tools.ant.loader;
+
+import java.io.IOException;
+import java.net.URL;
+import java.util.Enumeration;
+import junit.framework.TestCase;
+import org.apache.tools.ant.AntClassLoader;
+import org.apache.tools.ant.types.Path;
+import org.apache.tools.ant.util.CollectionUtils;
+
+public class AntClassLoader5Test extends TestCase {
+
+    /**
+     * Asserts that getResources won't return resources that cannot be
+     * seen by AntClassLoader but by ClassLoader.this.parent.
+     *
+     * @see https://issues.apache.org/bugzilla/show_bug.cgi?id=46752
+     */
+    public void testGetResources() throws IOException {
+        AntClassLoader acl = new AntClassLoader5(new EmptyLoader(), null,
+                                                 new Path(null), true);
+        assertNull(acl.getResource("META-INF/MANIFEST.MF"));
+        assertFalse(acl.getResources("META-INF/MANIFEST.MF").hasMoreElements());
+
+        // double check using system classloader as parent
+        acl = new AntClassLoader5(null, null, new Path(null), true);
+        assertNotNull(acl.getResource("META-INF/MANIFEST.MF"));
+        assertTrue(acl.getResources("META-INF/MANIFEST.MF").hasMoreElements());
+    }
+
+    public void testGetResourcesUsingFactory() throws IOException {
+        AntClassLoader acl =
+            AntClassLoader.newAntClassLoader(new EmptyLoader(), null,
+                                             new Path(null), true);
+        assertNull(acl.getResource("META-INF/MANIFEST.MF"));
+        assertFalse(acl.getResources("META-INF/MANIFEST.MF").hasMoreElements());
+    }
+
+    private static class EmptyLoader extends ClassLoader {
+        public URL getResource(String n) {
+            return null;
+        }
+        public Enumeration getResources(String n) {
+            return new CollectionUtils.EmptyEnumeration();
+        }
+    }
+}