1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19
20 package org.apache.onami.autobind.utils;
21
22 import com.google.common.base.Optional;
23
24 public final class ClassLoadingUtils {
25
26 private ClassLoadingUtils() {
27 //Utility Class
28 }
29
30 /**
31 * Load a class from the current class loader or the thread context class loader.
32 * The default behavior is to load the class using the class loader of ClassLoadingUtils and falls back
33 * to the thread context class loader if the class was not found.
34 * @param className
35 * @return
36 * @throws ClassNotFoundException
37 */
38 public static Class loadClass(String className) throws ClassNotFoundException {
39 Optional<ClassLoader> currentCloassLoader = Optional.of(ClassLoadingUtils.class.getClassLoader());
40 Optional<ClassLoader> threadContextClassLoader = Optional.<ClassLoader>fromNullable(Thread.currentThread().getContextClassLoader());
41 Optional<Class> clazz = tryLoad(className, currentCloassLoader).or(tryLoad(className, threadContextClassLoader));
42 if (!clazz.isPresent()) {
43 throw new ClassNotFoundException("Could not load class:" + className);
44 } else {
45 return clazz.get();
46 }
47 }
48
49 /**
50 * Try loading a {@link Class} with specified name from the specified {@link ClassLoader}.
51 *
52 * @param className The name of the class.
53 * @param classLoader The class loader.
54 * @return Returns an Optional class.
55 */
56 private static Optional<Class> tryLoad(String className, Optional<ClassLoader> classLoader) {
57 if (!classLoader.isPresent()) {
58 return Optional.absent();
59 } else {
60 try {
61 return Optional.<Class>of(classLoader.get().loadClass(className));
62 } catch (ClassNotFoundException ex) {
63 return Optional.absent();
64 }
65 }
66 }
67 }