Provided utility for loading classes that falls back to the Thread Context Class Loader if class is not found.

core/src/main/java/org/jclouds/rest/Providers.java

@@ -34,6 +34,7 @@ import java.util.Properties;
 import org.jclouds.javax.annotation.Nullable;
 
 import org.jclouds.PropertiesBuilder;
+import org.jclouds.util.ClassLoadingUtils;
 import org.jclouds.util.SaxUtils;
 
 import com.google.common.base.Function;
@@ -90,7 +91,7 @@ public class Providers {
                String provider = get(Splitter.on('.').split(keyString), 0);
                Class<RestContextBuilder<Object, Object>> clazz = Providers.resolveContextBuilderClass(provider,
                      properties);
-               if (type.isAssignableFrom(clazz))
+               if (clazz != null && type.isAssignableFrom(clazz))
                   return provider;
             } catch (ClassNotFoundException e) {
             } catch (Exception e) {
@@ -111,13 +112,18 @@ public class Providers {
       String asyncClassName = properties.getProperty(provider + ".async");
       if (syncClassName != null) {
          checkArgument(asyncClassName != null, "please configure async class for " + syncClassName);
-         Class.forName(syncClassName);
+         if(ClassLoadingUtils.loadClass(Providers.class, syncClassName) == null) {
-         Class.forName(asyncClassName);
+             throw new ClassNotFoundException();
-         return (Class<RestContextBuilder<S, A>>) (contextBuilderClassName != null ? Class
+         }
-               .forName(contextBuilderClassName) : RestContextBuilder.class);
+         if(ClassLoadingUtils.loadClass(Providers.class, asyncClassName) == null) {
+             throw new ClassNotFoundException();
+         }
+         return (Class<RestContextBuilder<S, A>>) (contextBuilderClassName != null ? ClassLoadingUtils.
+                 loadClass(Providers.class, contextBuilderClassName) : RestContextBuilder.class);
       } else {
          checkArgument(contextBuilderClassName != null, "please configure contextbuilder class for " + provider);
-         return (Class<RestContextBuilder<S, A>>) Class.forName(contextBuilderClassName);
+         return (Class<RestContextBuilder<S, A>>)  ClassLoadingUtils.
+                 loadClass(Providers.class, contextBuilderClassName);
       }
    }
 
@@ -142,7 +148,7 @@ public class Providers {
          NoSuchMethodException {
       String propertiesBuilderClassName = props.getProperty(providerName + ".propertiesbuilder", null);
       if (propertiesBuilderClassName != null) {
-         return (Class<PropertiesBuilder>) Class.forName(propertiesBuilderClassName);
+         return (Class<PropertiesBuilder>) ClassLoadingUtils.loadClass(Providers.class, propertiesBuilderClassName);
       } else {
          return PropertiesBuilder.class;
       }

core/src/main/java/org/jclouds/rest/RestContextFactory.java

@@ -35,6 +35,7 @@ import javax.inject.Inject;
 
 import org.jclouds.PropertiesBuilder;
 import org.jclouds.location.reference.LocationConstants;
+import org.jclouds.util.ClassLoadingUtils;
 import org.jclouds.util.Modules2;
 import org.jclouds.util.Strings2;
 
@@ -303,8 +304,8 @@ public class RestContextFactory {
       try {
          contextBuilderClass = Providers.resolveContextBuilderClass(providerName, props);
          propertiesBuilderClass = Providers.resolvePropertiesBuilderClass(providerName, props);
-         sync = (Class<S>) (syncClassName != null ? Class.forName(syncClassName) : null);
+         sync = (Class<S>) (syncClassName != null ? ClassLoadingUtils.loadClass(getClass(), syncClassName) : null);
-         async = (Class<A>) (asyncClassName != null ? Class.forName(asyncClassName) : null);
+         async = (Class<A>) (asyncClassName != null ? ClassLoadingUtils.loadClass(getClass(), asyncClassName) : null);
       } catch (IllegalArgumentException e) {
          throw new IllegalArgumentException(
                String.format(

core/src/main/java/org/jclouds/util/ClassLoadingUtils.java

@@ -0,0 +1,92 @@
+/**
+ * Licensed to jclouds, Inc. (jclouds) under one or more
+ * contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  jclouds 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.jclouds.util;
+
+import java.net.URL;
+import com.google.common.io.Resources;
+
+public class ClassLoadingUtils {
+
+    public ClassLoadingUtils() {
+        //Utility Class
+    }
+
+    /**
+     * Loads a class using the class loader.
+     * 1. The class loader of the context class is being used.
+     * 2. The thread context class loader is being used.
+     * If both approaches fail, returns null.
+     *
+     * @param contextClass The name of a context class to use.
+     * @param className    The name of the class to load
+     * @return The class or null if no class loader could load the class.
+     */
+    public static Class<?> loadClass(Class<?> contextClass, String className) {
+        Class clazz = null;
+        if (contextClass.getClassLoader() != null) {
+            clazz = silentLoadClass(className, contextClass.getClassLoader());
+        }
+        if (clazz == null && Thread.currentThread().getContextClassLoader() != null) {
+            clazz = silentLoadClass(className, Thread.currentThread().getContextClassLoader());
+        }
+        return clazz;
+    }
+
+    /**
+     * Returns the url of a resource.
+     * 1. The context class is being used.
+     * 2. The thread context class loader is being used.
+     * If both approach fail, returns null.
+     *
+     * @param contextClass
+     * @param resourceName
+     * @return
+     */
+    public static URL loadResource(Class contextClass, String resourceName) {
+        URL url = null;
+        if (contextClass != null) {
+            url = Resources.getResource(contextClass, resourceName);
+
+        }
+        if (url == null && Thread.currentThread().getContextClassLoader() != null) {
+            url = Thread.currentThread().getContextClassLoader().getResource(resourceName);
+        }
+        return url;
+    }
+
+
+    /**
+     * Loads a {@link Class} from the specified {@link ClassLoader} without throwing {@ClassNotFoundException}.
+     *
+     * @param className
+     * @param classLoader
+     * @return
+     */
+    private static Class<?> silentLoadClass(String className, ClassLoader classLoader) {
+        Class clazz = null;
+        if (classLoader != null && className != null) {
+            try {
+                clazz = classLoader.loadClass(className);
+            } catch (ClassNotFoundException e) {
+                //Ignore and proceed to the next class loader.
+            }
+        }
+        return clazz;
+    }
+}

core/src/main/java/org/jclouds/util/Modules2.java

@@ -47,13 +47,11 @@ public class Modules2 {
             @Override
             public Module apply(String from) {
                try {
-                  return (Module) Class.forName(from).newInstance();
+                  return (Module) ClassLoadingUtils.loadClass(Modules2.class, from).newInstance();
                } catch (InstantiationException e) {
                   throw new RuntimeException("error instantiating " + from, e);
                } catch (IllegalAccessException e) {
                   throw new RuntimeException("error instantiating " + from, e);
-               } catch (ClassNotFoundException e) {
-                  throw new RuntimeException("error instantiating " + from, e);
                }
             }
    

scriptbuilder/src/main/java/org/jclouds/scriptbuilder/util/Utils.java

@@ -36,6 +36,7 @@ import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Iterables;
 import com.google.common.io.CharStreams;
 import com.google.common.io.Resources;
+import org.jclouds.util.ClassLoadingUtils;
 
 /**
  * Utilities used to build init scripts.
@@ -135,7 +136,7 @@ public class Utils {
 
    public static String writeFunctionFromResource(String function, OsFamily family) {
       try {
-         String toReturn = CharStreams.toString(Resources.newReaderSupplier(Resources.getResource(Utils.class, String
+         String toReturn = CharStreams.toString(Resources.newReaderSupplier(ClassLoadingUtils.loadResource(Utils.class, String
                  .format("/functions/%s.%s", function, ShellToken.SH.to(family))), Charsets.UTF_8));
          String lf = ShellToken.LF.to(family);
          return toReturn.endsWith(lf) ? toReturn : new StringBuilder(toReturn).append(lf).toString();