Restore 1.1 operation

Refactor context class loader methods into a utility class
Add URL method to FileUtils (still need to pick that up in Project)
Rename xcatalog to XMLCatalog


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@271813 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -70,6 +70,7 @@ import java.io.ByteArrayOutputStream;
 import java.net.URL;
 import java.net.MalformedURLException;
 import org.apache.tools.ant.types.Path;
+import org.apache.tools.ant.util.LoaderUtils;
 
 /**
  * Used to load classes within ant with a different claspath from 
@@ -181,8 +182,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
      * The components of the classpath that the classloader searches
      * for classes.
      */
-    // XXX: Any reason this shouldn't be private?
-    Vector pathComponents  = new Vector();
+    private Vector pathComponents  = new Vector();
 
     /**
      * The project to which this class loader belongs.
@@ -228,7 +228,8 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
     private Hashtable zipFiles = new Hashtable();
 
     /**
-     * The context loader saved when setting the thread's current context loader.
+     * The context loader saved when setting the thread's current 
+     * context loader.
      */
     private ClassLoader savedContextLoader = null;
     /**
@@ -248,29 +249,18 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
      */
     private static Method defineClassProtectionDomain = null;
 
-    /**
-     * Reflection method reference for getContextClassLoader;
-     * used to avoid 1.1-compatibility problems.
-     */
-    private static Method getContextClassLoader = null;
-
-    /**
-     * Reflection method reference for setContextClassLoader;
-     * used to avoid 1.1-compatibility problems.
-     */
-    private static Method setContextClassLoader = null;
     
     // Set up the reflection-based Java2 methods if possible
     static {
         try {
-            getProtectionDomain = Class.class.getMethod("getProtectionDomain", new Class[0]);
-            Class protectionDomain = Class.forName("java.security.ProtectionDomain");
-            Class[] args = new Class[] {String.class, byte[].class, Integer.TYPE, Integer.TYPE, protectionDomain};
-            defineClassProtectionDomain = ClassLoader.class.getDeclaredMethod("defineClass", args);
-
-            getContextClassLoader = Thread.class.getMethod("getContextClassLoader", new Class[0]);
-            args = new Class[] {ClassLoader.class};
-            setContextClassLoader = Thread.class.getMethod("setContextClassLoader", args);
+            getProtectionDomain 
+                = Class.class.getMethod("getProtectionDomain", new Class[0]);
+            Class protectionDomain 
+                = Class.forName("java.security.ProtectionDomain");
+            Class[] args = new Class[] {String.class, byte[].class, 
+                Integer.TYPE, Integer.TYPE, protectionDomain};
+            defineClassProtectionDomain 
+                = ClassLoader.class.getDeclaredMethod("defineClass", args);
         }
         catch (Exception e) {}
     }
@@ -299,7 +289,8 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
                     addPathElement(pathElements[i]);
                 }
                 catch (BuildException e) {
-                    // ignore path elements which are invalid relative to the project
+                    // ignore path elements which are invalid 
+                    // relative to the project
                 }
             }
         }
@@ -345,7 +336,8 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
      *                    classloader should be consulted before trying to 
      *                    load the a class through this loader.
      */
-    public AntClassLoader(Project project, Path classpath, boolean parentFirst) {
+    public AntClassLoader(Project project, Path classpath, 
+                          boolean parentFirst) {
         this(null, project, classpath, parentFirst);
     }
 
@@ -398,26 +390,10 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
         if (isContextLoaderSaved) {
             throw new BuildException("Context loader has not been reset");
         }
-        if (getContextClassLoader != null && setContextClassLoader != null) {
-            try {
-                savedContextLoader
-                    = (ClassLoader)getContextClassLoader.invoke(Thread.currentThread(), new Object[0]);
-                Object[] args = null;
-                if ("only".equals(project.getProperty("build.sysclasspath"))) {
-                    args = new Object[] {this.getClass().getClassLoader()};
-                } else {
-                    args = new Object[] {this};
-                }
-                setContextClassLoader.invoke(Thread.currentThread(), args);
-                isContextLoaderSaved = true;
-            }
-            catch (InvocationTargetException ite) {
-                Throwable t = ite.getTargetException();
-                throw new BuildException(t.toString());
-            }
-            catch (Exception e) {
-                throw new BuildException(e.toString());
-            }
+        if (LoaderUtils.isContextLoaderAvailable()) {
+            savedContextLoader = LoaderUtils.getContextClassLoader();
+            LoaderUtils.setContextClassLoader(this);
+            isContextLoaderSaved = true;
         }
     }
 
@@ -425,21 +401,11 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
      * Resets the current thread's context loader to its original value.
      */
     public void resetThreadContextLoader() {
-        if (isContextLoaderSaved &&
-                getContextClassLoader != null && setContextClassLoader != null) {
-            try {
-                Object[] args = new Object[] {savedContextLoader};
-                setContextClassLoader.invoke(Thread.currentThread(), args);
-                savedContextLoader = null;
-                isContextLoaderSaved = false;
-            }
-            catch (InvocationTargetException ite) {
-                Throwable t = ite.getTargetException();
-                throw new BuildException(t.toString());
-            }
-            catch (Exception e) {
-                throw new BuildException(e.toString());
-            }
+        if (LoaderUtils.isContextLoaderAvailable() 
+            && isContextLoaderSaved) {
+            LoaderUtils.setContextClassLoader(savedContextLoader);
+            savedContextLoader = null;
+            isContextLoaderSaved = false;
         }
     }
 
@@ -575,7 +541,8 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
      * @exception ClassNotFoundException if the requested class does not exist
      *                                   on this loader's classpath.
      */
-    public Class forceLoadClass(String classname) throws ClassNotFoundException {
+    public Class forceLoadClass(String classname) 
+         throws ClassNotFoundException {
         log("force loading " + classname, Project.MSG_DEBUG);
 
         Class theClass = findLoadedClass(classname);
@@ -603,7 +570,8 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
      * @exception ClassNotFoundException if the requested class does not exist
      * on this loader's classpath.
      */
-    public Class forceLoadSystemClass(String classname) throws ClassNotFoundException {
+    public Class forceLoadSystemClass(String classname) 
+         throws ClassNotFoundException {
         log("force system loading " + classname, Project.MSG_DEBUG);
 
         Class theClass = findLoadedClass(classname);
@@ -674,8 +642,8 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
      *         the resource cannot be found on the loader's classpath.
      */
     private InputStream loadResource(String name) {
-        // we need to search the components of the path to see if we can find the
-        // class we want.
+        // we need to search the components of the path to see if we can 
+        // find the class we want.
         InputStream stream = null;
 
         for (Enumeration e = pathComponents.elements(); e.hasMoreElements() && stream == null; ) {
@@ -743,8 +711,9 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
             }
         }
         catch (Exception e) {
-            log("Ignoring Exception " + e.getClass().getName() + ": " + e.getMessage() +
-                " reading resource " + resourceName + " from " + file, Project.MSG_VERBOSE);
+            log("Ignoring Exception " + e.getClass().getName() 
+                + ": " + e.getMessage() + " reading resource " + resourceName 
+                + " from " + file, Project.MSG_VERBOSE);
         }
 
         return null;
@@ -765,7 +734,8 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
     private boolean isParentFirst(String resourceName) {
         // default to the global setting and then see
         // if this class belongs to a package which has been
-        // designated to use a specific loader first (this one or the parent one)
+        // designated to use a specific loader first 
+        // (this one or the parent one)
         
         // XXX - shouldn't this always return false in isolated mode?
         
@@ -803,11 +773,12 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
      *         adequate privileges to get the resource.
      */
     public URL getResource(String name) {
-        // we need to search the components of the path to see if we can find the
-        // class we want.
+        // we need to search the components of the path to see if 
+        // we can find the class we want.
         URL url = null;
         if (isParentFirst(name)) {
-            url = (parent == null) ? super.getResource(name) : parent.getResource(name);
+            url = (parent == null) ? super.getResource(name) 
+                                   : parent.getResource(name);
         }
 
         if (url != null) {
@@ -881,7 +852,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
 
                 if (resource.exists()) {
                     try {
-                        return new URL("file:"+resource.toString());
+                        return new URL("file:" + resource.toString());
                     } catch (MalformedURLException ex) {
                         return null;
                     }
@@ -897,7 +868,8 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
                 ZipEntry entry = zipFile.getEntry(resourceName);
                 if (entry != null) {
                     try {
-                        return new URL("jar:file:"+file.toString()+"!/"+entry);
+                        return new URL("jar:file:" + file.toString() 
+                            + "!/" + entry);
                     } catch (MalformedURLException ex) {
                         return null;
                     }
@@ -931,7 +903,8 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
      * on the system classpath (when not in isolated mode) or this loader's 
      * classpath.
      */
-    protected Class loadClass(String classname, boolean resolve) throws ClassNotFoundException {
+    protected Class loadClass(String classname, boolean resolve) 
+         throws ClassNotFoundException {
 
         Class theClass = findLoadedClass(classname);
         if (theClass != null) {
@@ -941,24 +914,28 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
         if (isParentFirst(classname)) {
             try {
                 theClass = findBaseClass(classname);
-                log("Class " + classname + " loaded from parent loader", Project.MSG_DEBUG);
+                log("Class " + classname + " loaded from parent loader", 
+                    Project.MSG_DEBUG);
             }
             catch (ClassNotFoundException cnfe) {
                 theClass = findClass(classname);
-                log("Class " + classname + " loaded from ant loader", Project.MSG_DEBUG);
+                log("Class " + classname + " loaded from ant loader", 
+                    Project.MSG_DEBUG);
             }
         }
         else {
             try {
                 theClass = findClass(classname);
-                log("Class " + classname + " loaded from ant loader", Project.MSG_DEBUG);
+                log("Class " + classname + " loaded from ant loader", 
+                    Project.MSG_DEBUG);
             }
             catch (ClassNotFoundException cnfe) {
                 if (ignoreBase) {
                     throw cnfe;
                 }
                 theClass = findBaseClass(classname);
-                log("Class " + classname + " loaded from parent loader", Project.MSG_DEBUG);
+                log("Class " + classname + " loaded from parent loader", 
+                    Project.MSG_DEBUG);
             }
         }
 
@@ -1008,12 +985,16 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
         byte[] classData = baos.toByteArray();
 
         // Simply put:
-        // defineClass(classname, classData, 0, classData.length, Project.class.getProtectionDomain());
+        // defineClass(classname, classData, 0, classData.length, 
+        //             Project.class.getProtectionDomain());
         // Made more elaborate to be 1.1-safe.
         if (defineClassProtectionDomain != null) {
             try {
-                Object domain = getProtectionDomain.invoke(Project.class, new Object[0]);
-                Object[] args = new Object[] {classname, classData, new Integer(0), new Integer(classData.length), domain};
+                Object domain 
+                    = getProtectionDomain.invoke(Project.class, new Object[0]);
+                Object[] args 
+                    = new Object[] {classname, classData, new Integer(0), 
+                                    new Integer(classData.length), domain};
                 return (Class)defineClassProtectionDomain.invoke(this, args);
             }
             catch (InvocationTargetException ite) {
@@ -1066,9 +1047,10 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
      * @exception ClassNotFoundException if the requested class does not exist
      * on this loader's classpath.
      */
-    private Class findClassInComponents(String name) throws ClassNotFoundException {
-        // we need to search the components of the path to see if we can find the
-        // class we want.
+    private Class findClassInComponents(String name) 
+         throws ClassNotFoundException {
+        // we need to search the components of the path to see if 
+        // we can find the class we want.
         InputStream stream = null;
         String classFilename = getClassFilename(name);
         try {
@@ -1082,7 +1064,8 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
                 }
                 catch (IOException ioe) {
                     // ioe.printStackTrace();
-                    log("Exception reading component " + pathComponent , Project.MSG_VERBOSE);
+                    log("Exception reading component " + pathComponent , 
+                        Project.MSG_VERBOSE);
                 }
             }
 
@@ -1143,6 +1126,8 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
 
     /**
      * Empty implementation to satisfy the BuildListener interface.
+     *
+     * @param event the buildStarted event
      */
     public void buildStarted(BuildEvent event) {
     }
@@ -1150,6 +1135,8 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
     /**
      * Cleans up any resources held by this classloader at the end
      * of a build.
+     *
+     * @param event the buildFinished event
      */
     public void buildFinished(BuildEvent event) {
         cleanup();
@@ -1157,30 +1144,40 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
 
     /**
      * Empty implementation to satisfy the BuildListener interface.
+     *
+     * @param event the targetStarted event
      */
     public void targetStarted(BuildEvent event) {
     }
 
     /**
      * Empty implementation to satisfy the BuildListener interface.
+     *
+     * @param event the targetFinished event
      */
     public void targetFinished(BuildEvent event) {
     }
 
     /**
      * Empty implementation to satisfy the BuildListener interface.
+     *
+     * @param event the taskStarted event
      */
     public void taskStarted(BuildEvent event) {
     }
 
     /**
      * Empty implementation to satisfy the BuildListener interface.
+     *
+     * @param event the taskFinished event
      */
     public void taskFinished(BuildEvent event) {
     }
 
     /**
      * Empty implementation to satisfy the BuildListener interface.
+     *
+     * @param event the messageLogged event
      */
     public void messageLogged(BuildEvent event) {
     }

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

@@ -70,6 +70,7 @@ import java.lang.reflect.Method;
 
 import org.xml.sax.AttributeList;
 import org.apache.tools.ant.helper.ProjectHelperImpl;
+import org.apache.tools.ant.util.LoaderUtils;
 
 /**
  * Configures a Project (complete with Targets and Tasks) based on
@@ -236,30 +237,11 @@ public class ProjectHelper {
     public static ClassLoader getContextClassLoader()
         throws BuildException
     {
-        // Are we running on a JDK 1.2 or later system?
-        Method method = null;
-        try {
-            method = Thread.class.getMethod("getContextClassLoader", null);
-        } catch (NoSuchMethodException e) {
-            // we are running on JDK 1.1
-            return null; 
-        }
-
-        // Get the thread context class loader (if there is one)
-        ClassLoader classLoader = null;
-        try {
-            classLoader = (ClassLoader)
-                method.invoke(Thread.currentThread(), null);
-        } catch (IllegalAccessException e) {
-            throw new BuildException
-                ("Unexpected IllegalAccessException", e);
-        } catch (InvocationTargetException e) {
-            throw new BuildException
-                ("Unexpected InvocationTargetException", e);
+        if (!LoaderUtils.isContextLoaderAvailable()) {
+            return null;
         }
-
-        // Return the selected class loader
-        return (classLoader);
+        
+        return LoaderUtils.getContextClassLoader();
     }
 
     // -------------------- Static utils, used by most helpers -------------------- 

src/main/org/apache/tools/ant/taskdefs/XSLTProcess.java

@@ -65,7 +65,7 @@ import org.apache.tools.ant.AntClassLoader;
 import org.apache.tools.ant.types.Path;
 import org.apache.tools.ant.types.Reference;
 import org.apache.tools.ant.util.FileUtils;
-import org.apache.tools.ant.types.XCatalog;
+import org.apache.tools.ant.types.XMLCatalog;
 import org.xml.sax.EntityResolver;
 
 /**
@@ -142,7 +142,7 @@ public class XSLTProcess extends MatchingTask implements XSLTLogger {
     private String outputtype = null;
     
     /** for resolving entities such as dtds */
-    private XCatalog xcatalog;
+    private XMLCatalog xmlCatalog;
     
     /** Name of the TRAX Liason class */
     private static final String TRAX_LIAISON_CLASS =
@@ -344,12 +344,12 @@ public class XSLTProcess extends MatchingTask implements XSLTLogger {
     }
     
     /**
-     * store the xcatalog for resolving entities
+     * store the xml catalog for resolving entities
      * 
-     * @param xcatalog the xcatalog instance to use to look up DTDs
+     * @param xmlCatalog the XMLCatalog instance to use to look up DTDs
      */
-    public void addXcatalog(XCatalog xcatalog) {
-        this.xcatalog = xcatalog;
+    public void addXMLcatalog(XMLCatalog xmlCatalog) {
+        this.xmlCatalog = xmlCatalog;
     }
     
     /**
@@ -660,16 +660,16 @@ public class XSLTProcess extends MatchingTask implements XSLTLogger {
                 Param p = (Param)e.nextElement();
                 liaison.addParam( p.getName(), p.getExpression() );
             }
-            // if liaison is a TraxLiason, use XCatalog as the entity
+            // if liaison is a TraxLiason, use XMLCatalog as the entity
             // resolver
             if (liaison.getClass().getName().equals(TRAX_LIAISON_CLASS) &&
-                xcatalog != null) {
+                xmlCatalog != null) {
                 log("Configuring TraxLiaison and calling entity resolver",
                     Project.MSG_DEBUG);
                 Method resolver = liaison.getClass()
                                     .getDeclaredMethod("setEntityResolver", 
                                         new Class[] {EntityResolver.class});
-                resolver.invoke(liaison, new Object[] {xcatalog});
+                resolver.invoke(liaison, new Object[] {xmlCatalog});
             }
         } catch (Exception ex) {
             log("Failed to read stylesheet " + stylesheet, Project.MSG_INFO);

src/main/org/apache/tools/ant/types/XCatalog.java → src/main/org/apache/tools/ant/types/XMLCatalog.java

@@ -59,13 +59,15 @@ import java.io.FileInputStream;
 import java.io.InputStream;
 import java.io.IOException;
 import java.net.URL;
-import java.util.Enumeration;
+import java.util.Iterator;
 import java.util.Vector;
 import org.apache.tools.ant.BuildException;
 import org.apache.tools.ant.Project;
 import org.xml.sax.EntityResolver;
 import org.xml.sax.InputSource;
 import org.xml.sax.SAXException;
+import org.apache.tools.ant.util.LoaderUtils;
+import org.apache.tools.ant.util.FileUtils;
 
 /**
  * This data type provides a catalog of DTD locations
@@ -90,7 +92,9 @@ import org.xml.sax.SAXException;
  * @author  dIon Gillard
  * @version $Id$
  */
-public class XCatalog extends DataType implements Cloneable, EntityResolver {
+public class XMLCatalog extends DataType implements Cloneable, EntityResolver {
+    
+    private FileUtils fileUtils = FileUtils.newFileUtils();
     
     //-- Fields ----------------------------------------------------------------
     
@@ -121,7 +125,7 @@ public class XCatalog extends DataType implements Cloneable, EntityResolver {
      * @param aDTD the DTDLocation instance to be aded to the catalog
      */
     private void addElement(DTDLocation aDTD) {
-        getElements().addElement(aDTD);
+        getElements().add(aDTD);
     }
     
     /**
@@ -135,7 +139,7 @@ public class XCatalog extends DataType implements Cloneable, EntityResolver {
         if (isReference()) {
             throw noChildrenAllowed();
         }
-        getElements().addElement(dtd);
+        getElements().add(dtd);
     }
     
     /**
@@ -165,9 +169,9 @@ public class XCatalog extends DataType implements Cloneable, EntityResolver {
         // change this to get the objects from the other reference
         Object o = r.getReferencedObject(getProject());
         // we only support references to other XCatalogs
-        if (o instanceof XCatalog) {
+        if (o instanceof XMLCatalog) {
             // set all elements from referenced catalog to this one
-            XCatalog catalog = (XCatalog) o;
+            XMLCatalog catalog = (XMLCatalog) o;
             setElements(catalog.getElements());
         } else {
             String msg = r.getRefId() + " doesn\'t refer to an XCatalog";
@@ -191,16 +195,20 @@ public class XCatalog extends DataType implements Cloneable, EntityResolver {
                 Project.MSG_DEBUG);
             File dtdFile = new File(matchingDTD.getLocation());
             if (dtdFile.exists() && dtdFile.canRead()) {
-                source = new InputSource( new FileInputStream(dtdFile) );
-                source.setSystemId(dtdFile.toURL().toExternalForm());
+                source = new InputSource(new FileInputStream(dtdFile));
+                URL dtdFileURL = fileUtils.getFileURL(dtdFile);
+                source.setSystemId(dtdFileURL.toExternalForm());
                 log("matched a readable file", Project.MSG_DEBUG);
             } else {
                 // check if publicId is a resource
                 // FIXME: ClassLoader: should this be context?
-                ClassLoader loader 
-                    = Thread.currentThread().getContextClassLoader();
-                InputStream is = loader.getResourceAsStream(
-                    matchingDTD.getLocation() );
+                ClassLoader loader = LoaderUtils.getContextClassLoader();
+                if (loader == null) {
+                    loader = getClass().getClassLoader();
+                }
+                
+                InputStream is 
+                    = loader.getResourceAsStream(matchingDTD.getLocation());
                 if (is != null) {
                     source = new InputSource(is);
                     source.setSystemId(loader.getResource(
@@ -242,10 +250,10 @@ public class XCatalog extends DataType implements Cloneable, EntityResolver {
      *         of the DTD or null if no such information is available
      */
     private DTDLocation findMatchingDTD(String publicId) {
-        Enumeration elements = getElements().elements();
+        Iterator elements = getElements().iterator();
         DTDLocation element = null;
-        while (elements.hasMoreElements()) {
-            element = (DTDLocation)elements.nextElement();
+        while (elements.hasNext()) {
+            element = (DTDLocation)elements.next();
             if (element.getPublicId().equals(publicId)) {
                 return element;
             }

src/main/org/apache/tools/ant/types/defaults.properties

@@ -8,5 +8,5 @@ description=org.apache.tools.ant.types.Description
 classfileset=org.apache.tools.ant.types.optional.depend.ClassfileSet
 substitution=org.apache.tools.ant.types.Substitution
 regexp=org.apache.tools.ant.types.RegularExpression
-xcatalog=org.apache.tools.ant.types.XCatalog
+xmlcatalog=org.apache.tools.ant.types.XMLCatalog
 

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

@@ -74,6 +74,8 @@ import java.util.Random;
 import java.util.Stack;
 import java.util.StringTokenizer;
 import java.util.Vector;
+import java.net.URL;
+import java.net.MalformedURLException;
 
 import org.apache.tools.ant.BuildException;
 import org.apache.tools.ant.Project;
@@ -115,6 +117,25 @@ public class FileUtils {
      */
     protected FileUtils() {}
 
+    /**
+     * Get the URL for a file taking into account # characters
+     *
+     * @param file the file whose URL representation is required.
+     * @return The FileURL value
+     * @throws MalformedURLException if the URL representation cannot be
+     *      formed.
+     */
+    public URL getFileURL(File file) throws MalformedURLException {
+        String uri = "file:" + file.getAbsolutePath().replace('\\', '/');
+        for (int i = uri.indexOf('#'); i != -1; i = uri.indexOf('#')) {
+            uri = uri.substring(0, i) + "%23" + uri.substring(i + 1);
+        }
+        if (file.isDirectory()) {
+            uri += "/";
+        }
+        return new URL(uri);
+    }
+    
     /**
      * Convienence method to copy a file from a source to a destination.
      * No filtering is performed.

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

@@ -0,0 +1,150 @@
+/*
+ * The Apache Software License, Version 1.1
+ *
+ * Copyright (c) 2002 The Apache Software Foundation.  All rights
+ * reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. The end-user documentation included with the redistribution, if
+ *    any, must include the following acknowlegement:
+ *       "This product includes software developed by the
+ *        Apache Software Foundation (http://www.apache.org/)."
+ *    Alternately, this acknowlegement may appear in the software itself,
+ *    if and wherever such third-party acknowlegements normally appear.
+ *
+ * 4. The names "The Jakarta Project", "Ant", and "Apache Software
+ *    Foundation" must not be used to endorse or promote products derived
+ *    from this software without prior written permission. For written
+ *    permission, please contact apache@apache.org.
+ *
+ * 5. Products derived from this software may not be called "Apache"
+ *    nor may "Apache" appear in their names without prior written
+ *    permission of the Apache Group.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
+ * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ * ====================================================================
+ *
+ * This software consists of voluntary contributions made by many
+ * individuals on behalf of the Apache Software Foundation.  For more
+ * information on the Apache Software Foundation, please see
+ * <http://www.apache.org/>.
+ */
+package org.apache.tools.ant.util;
+
+import java.lang.reflect.InvocationTargetException;
+
+import java.lang.reflect.Method;
+import org.apache.tools.ant.BuildException;
+
+/**
+ * ClassLoader utility methods
+ *
+ * @author <a href="mailto:conor@apache.org">Conor MacNeill</a>
+ * @created 11 March 2002
+ */
+public class LoaderUtils {
+    /** The getContextClassLoader method */
+    private static Method getContextClassLoader;
+    /** The setContextClassLoader method */
+    private static Method setContextClassLoader;
+
+    // Set up the reflection-based Java2 methods if possible
+    static {
+        try {
+            getContextClassLoader
+                 = Thread.class.getMethod("getContextClassLoader",
+                new Class[0]);
+            Class[] setContextArgs = new Class[]{ClassLoader.class};
+            setContextClassLoader
+                 = Thread.class.getMethod("setContextClassLoader",
+                setContextArgs);
+        } catch (Exception e) {
+            // ignore any problems accessing the methods - probably JDK 1.1
+        }
+    }
+
+    /**
+     * JDK1.1 compatible access to get the context class loader. Has no
+     * effect on JDK 1.1
+     *
+     * @param loader the ClassLoader to be used as the context class loader
+     *      on the current thread.
+     */
+    public static void setContextClassLoader(ClassLoader loader) {
+        if (setContextClassLoader == null) {
+            return;
+        }
+
+        try {
+            Thread currentThread = Thread.currentThread();
+            setContextClassLoader.invoke(currentThread,
+                new Object[]{loader});
+        } catch (IllegalAccessException e) {
+            throw new BuildException
+                ("Unexpected IllegalAccessException", e);
+        } catch (InvocationTargetException e) {
+            throw new BuildException
+                ("Unexpected InvocationTargetException", e);
+        }
+
+    }
+
+
+    /**
+     * JDK1.1 compatible access to set the context class loader.
+     *
+     * @return the ClassLoader instance being used as the context
+     *      classloader on the current thread. Returns null on JDK 1.1
+     */
+    public static ClassLoader getContextClassLoader() {
+        if (getContextClassLoader == null) {
+            return null;
+        }
+
+        try {
+            Thread currentThread = Thread.currentThread();
+            return (ClassLoader)getContextClassLoader.invoke(currentThread,
+                new Object[0]);
+        } catch (IllegalAccessException e) {
+            throw new BuildException
+                ("Unexpected IllegalAccessException", e);
+        } catch (InvocationTargetException e) {
+            throw new BuildException
+                ("Unexpected InvocationTargetException", e);
+        }
+    }
+
+    /**
+     * Indicates if the context class loader methods are available
+     *
+     * @return true if the get and set methods dealing with the context
+     *      classloader are available.
+     */
+    public static boolean isContextLoaderAvailable() {
+        return getContextClassLoader != null &&
+            setContextClassLoader != null;
+    }
+}
+