| /* |
| * 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.flink.util; |
| |
| import org.apache.flink.annotation.Public; |
| |
| /** |
| * Sets a context class loader in a "try-with-resources" pattern. |
| * |
| * <pre>{@code |
| * try (TemporaryClassLoaderContext ignored = TemporaryClassLoaderContext.of(classloader)) { |
| * // code that needs the context class loader |
| * } |
| * }</pre> |
| * |
| * <p>This is conceptually the same as the code below. |
| * |
| * <pre>{@code |
| * ClassLoader original = Thread.currentThread().getContextClassLoader(); |
| * Thread.currentThread().setContextClassLoader(classloader); |
| * try { |
| * // code that needs the context class loader |
| * } finally { |
| * Thread.currentThread().setContextClassLoader(original); |
| * } |
| * }</pre> |
| */ |
| @Public |
| public final class TemporaryClassLoaderContext implements AutoCloseable { |
| |
| /** |
| * Sets the context class loader to the given ClassLoader and returns a resource that sets it |
| * back to the current context ClassLoader when the resource is closed. |
| * |
| * <pre>{@code |
| * try (TemporaryClassLoaderContext ignored = TemporaryClassLoaderContext.of(classloader)) { |
| * // code that needs the context class loader |
| * } |
| * }</pre> |
| */ |
| public static TemporaryClassLoaderContext of(ClassLoader cl) { |
| final Thread t = Thread.currentThread(); |
| final ClassLoader original = t.getContextClassLoader(); |
| |
| t.setContextClassLoader(cl); |
| |
| return new TemporaryClassLoaderContext(t, original); |
| } |
| |
| // ------------------------------------------------------------------------ |
| |
| private final Thread thread; |
| |
| private final ClassLoader originalContextClassLoader; |
| |
| private TemporaryClassLoaderContext(Thread thread, ClassLoader originalContextClassLoader) { |
| this.thread = thread; |
| this.originalContextClassLoader = originalContextClassLoader; |
| } |
| |
| @Override |
| public void close() { |
| thread.setContextClassLoader(originalContextClassLoader); |
| } |
| } |